Potatoes and Human Health, Part I
Tuesday, September 21, 2010 12:15 AM
Potatoes: an Introduction
Over 10,000 years ago, on the shores of lake Titicaca in what is now Peru, a culture began to cultivate a species of wild potato, Solanum tuberosum. They gradually transformed it into a plant that efficiently produces roundish starchy tubers, in a variety of strains that suited the climactic and gastronomic needs of various populations. These early farmers could not have understood at the time that the plant they were selecting would become the most productive crop in the world*, and eventually feed billions of people around the globe.
Wild potatoes, which were likely consumed by hunter-gatherers before domestication, are higher in toxic glycoalkaloids. These are defensive compounds that protect against insects, infections and... hungry animals. Early farmers selected varieties that are low in bitter glycoalkaloids, which are the ancestors of most modern potatoes, however they didn't abandon the high-glycoalkaloid varieties. These were hardier and more tolerant of high altitudes, cold temperatures and pests. Cultures living high in the Andes developed a method to take advantage of these hardy but toxic potatoes, as well as their own harsh climate: they invented chuños. These are made by leaving potatoes out in the open, where they are frozen at night, stomped underfoot and dried in the sun for many days**. What results is a dried potato with a low glycoalkaloid content that can be stored for a year or more.
Nutritional Qualities
From a nutritional standpoint, potatoes are a mixed bag. On one hand, if I had to pick a single food to eat exclusively for a while, potatoes would be high on the list. One reason is that they contain an adequate amount of complete protein, meaning they don't have to be mixed with another protein source as with grains and legumes. Another reason is that a number of cultures throughout history have successfully relied on the potato as their principal source of calories, and several continue to do so. A third reason is that they're eaten in an unrefined, fresh state.
Potatoes contain an adequate amount of many essential minerals, and due to their low phytic acid content (1), the minerals they contain are well absorbed. They're rich in magnesium and copper, two minerals that are important for insulin sensitivity and cardiovascular health (2, 3). They're also high in potassium and vitamin C. Overall, they have a micronutrient content that compares favorably with other starchy root vegetables such as taro and cassava (4, 5, 6). Due to their very low fat content, potatoes contain virtually no omega-6, and thus do not contribute to an excess of these essential fatty acids.
On the other hand, I don't have to eat potatoes exclusively, so what do they have to offer a mixed diet? They have a high glycemic index, which means they raise blood sugar more than an equivalent serving of most carbohydrate foods, although I'm not convinced that's a problem in people with good blood sugar control (7, 8). They're low in fiber, which could hypothetically lead to a reduction in the number and diversity of gut bacteria in the absence of other fiber sources. Sweet potatoes, an unrelated species, contain more micronutrients and fiber, and have been a central food source for healthy cultures (9). However, the main reasons temperate-climate cultures throughout the world eat potatoes is they yield well, they're easily digested, they fill you up and they taste good.
In the next post, I'll delve into the biology and toxicology of potato glycoalkaloids, and review some animal data. In further posts, I'll address the most important question of all: what happens when a person eats mostly potatoes... for months, years, and generations?
* In terms of calories produced per acre.
** A simplified description. The process can actually be rather involved, with several different drying, stomping and leaching steps.
Tuesday, September 21, 2010 12:15 AM
Potatoes: an Introduction
Over 10,000 years ago, on the shores of lake Titicaca in what is now Peru, a culture began to cultivate a species of wild potato, Solanum tuberosum. They gradually transformed it into a plant that efficiently produces roundish starchy tubers, in a variety of strains that suited the climactic and gastronomic needs of various populations. These early farmers could not have understood at the time that the plant they were selecting would become the most productive crop in the world*, and eventually feed billions of people around the globe.
Wild potatoes, which were likely consumed by hunter-gatherers before domestication, are higher in toxic glycoalkaloids. These are defensive compounds that protect against insects, infections and... hungry animals. Early farmers selected varieties that are low in bitter glycoalkaloids, which are the ancestors of most modern potatoes, however they didn't abandon the high-glycoalkaloid varieties. These were hardier and more tolerant of high altitudes, cold temperatures and pests. Cultures living high in the Andes developed a method to take advantage of these hardy but toxic potatoes, as well as their own harsh climate: they invented chuños. These are made by leaving potatoes out in the open, where they are frozen at night, stomped underfoot and dried in the sun for many days**. What results is a dried potato with a low glycoalkaloid content that can be stored for a year or more.
Nutritional Qualities
From a nutritional standpoint, potatoes are a mixed bag. On one hand, if I had to pick a single food to eat exclusively for a while, potatoes would be high on the list. One reason is that they contain an adequate amount of complete protein, meaning they don't have to be mixed with another protein source as with grains and legumes. Another reason is that a number of cultures throughout history have successfully relied on the potato as their principal source of calories, and several continue to do so. A third reason is that they're eaten in an unrefined, fresh state.
Potatoes contain an adequate amount of many essential minerals, and due to their low phytic acid content (1), the minerals they contain are well absorbed. They're rich in magnesium and copper, two minerals that are important for insulin sensitivity and cardiovascular health (2, 3). They're also high in potassium and vitamin C. Overall, they have a micronutrient content that compares favorably with other starchy root vegetables such as taro and cassava (4, 5, 6). Due to their very low fat content, potatoes contain virtually no omega-6, and thus do not contribute to an excess of these essential fatty acids.
On the other hand, I don't have to eat potatoes exclusively, so what do they have to offer a mixed diet? They have a high glycemic index, which means they raise blood sugar more than an equivalent serving of most carbohydrate foods, although I'm not convinced that's a problem in people with good blood sugar control (7, 8). They're low in fiber, which could hypothetically lead to a reduction in the number and diversity of gut bacteria in the absence of other fiber sources. Sweet potatoes, an unrelated species, contain more micronutrients and fiber, and have been a central food source for healthy cultures (9). However, the main reasons temperate-climate cultures throughout the world eat potatoes is they yield well, they're easily digested, they fill you up and they taste good.
In the next post, I'll delve into the biology and toxicology of potato glycoalkaloids, and review some animal data. In further posts, I'll address the most important question of all: what happens when a person eats mostly potatoes... for months, years, and generations?
* In terms of calories produced per acre.
** A simplified description. The process can actually be rather involved, with several different drying, stomping and leaching steps.
Speaking at Wise Traditions 2010
I'm happy to announce that I'll be presenting at the Weston A. Price foundation's 2010 Wise Traditions conference. The conference will be held in King of Prussia, Pennsylvania, Nov 12-14. The theme is the politics of food.
Sally Fallon Morell has invited me to give a talk on the diet and health of Pacific islanders. The talk will be titled "Kakana Dina: Diet and Health in the Pacific Islands", and it will take place on Sunday, November 14th from 4:00 to 5:20 pm. In preparation for the talk, I've read eight books and countless journal articles. Although some of the material will be familiar to people who follow the blog, I will not be rehashing what I've already published. I have nearly an hour and a half to talk, so I'll be going into some depth on the natural history and traditional food habits of Pacific island populations. Not just macronutrient breakdowns... specific foods and traditional preparation methods.
Learn about the health of traditional Pacific island populations, and what has changed since Western contact. Learn about traditional cooking and fermentation techniques. See unpublished photos from the Kitava study, courtesy of Dr. Staffan Lindeberg. Learn about the nutritional and ceremonial role of mammals including pork... and the most gruesome food of all.
I hope to see you there!
Kitava photo courtesy of Dr. Staffan Lindeberg
Dogen Zenji on Nutritionism
Sunday, September 12, 2010 3:55 AM
Dogen Zenji was the man who brought the Soto lineage of Zen Buddhism to Japan. He was a prolific writer, and many of his texts are respected both inside and outside the Soto Zen community. Last week, my Zen group was discussing the Genjo Koan, one of his works that is frequently used as a chant. Here's an excerpt. It may seem cryptic but bear with me:
...when you sail out in a boat to the middle of an ocean where no land is in sight, and view the four directions, the ocean looks circular, and does not look any other way. But the ocean is neither round or square; its features are infinite in variety... It only look circular as far as you can see at that time. All things are like this.
Though there are many features in the dusty world and the world beyond conditions, you see and understand only what your eye of practice can reach. In order to learn the nature of the myriad things, you must know that although they may look round or square, the other features of oceans and mountains are infinite in variety; whole worlds are there. It is so not only around you, but also directly beneath your feet, or in a drop of water.
What Dogen meant, among other things, is that the world is much more complex than what our conscious minds can perceive or understand. It was true in the 13th century, and it's still true today, despite our greatly expanded understanding of the natural world.
We can apply this principle to nutrition. For example, what is red palm oil? Two hundred years ago, perhaps we only knew a few basic facts about it. It's a fat, it's red, it comes from an African palm fruit and it has a particular melting point and flavor. Then we learned about vitamins, so we knew it contained vitamin E, carotenes (provitamin A), and vitamin K. Then fatty acid composition, so we found out it's mostly palmitic and oleic acids. Now we know red palm oil contains an array of polyphenols, sterols, coenzyme Q10 and many other non-essential constituents. We don't know much about the biological effects of most of these substances, particularly in combination with one another.
Add to that the fact that every batch of red palm oil is different, due to strain, terroir, processing, storage, et cetera. We know what the concept "red palm oil" means, roughly, but the details are infinitely complex. Now feed it to a human, who is not only incredibly complex himself, but genetically and epigenetically unique. How can we possibly guess the outcome of this encounter based on the chemical composition of red palm oil? That's essentially what nutritionism attempts to do.
To be fair, nutritionism does work sometimes. For example, we can pretty well guess that a handful of wild almonds containing a lot of cyanide won't be healthy to eat, due at least in part to the cyanide. But outside extreme examples like this, we're in a gray zone that needs to be informed by empirical observation. In other words, what happens when the person in question actually eats the red palm oil? What happened when a large group of people in West Africa ate red palm oil for thousands of years? Those questions are the reason why I'm so interested in understanding the lives of healthy non-industrial cultures.
I'm not criticizing reductionist science or controlled experiments (which I perform myself); I just think they need to be kept in context. I believe they should be interpreted within the framework of more basic empirical observations*.
One of the most important aspects of scientific maturity is learning to accept and manage uncertainty and your own ignorance. Some things are more certain than others, but most aren't set in stone. I think Dogen would tell us to be wary of nutritionism, and other forms of overconfidence.
* Wikipedia's definition of empirical: "information gained by means of observation, experience, or experiment." As opposed to inferences made from experiments not directly related to the question at hand.
The China Study on Wheat
Friday, September 03, 2010 12:10 PM
Denise Minger has just put up another great China Study post that's worth reading if you haven't already. Denise has been busy applying her statistics skills to the mountain of data the study collected. She noted in a previous post that wheat intake was strongly associated with coronary heart disease (CHD), the quintessential modern cardiovascular disease. I, and several other people, requested that she work her mathmagic to see if the association could be due to some other factor. For example, wheat is eaten mostly in the Northern regions of China, and CHD rates are generally higher at higher latitudes (vitamin D insufficiency?). This is true in Europe as well, and may be partly responsible for the purported benefits of the Mediterranean diet. You can mathematically determine if the association between wheat and CHD is simply due to the fact that wheat eaters live further North.
To make a long story short, nothing could explain the association except wheat itself, even latitude. Furthermore, she found a strong association between wheat intake and body mass index, typically a predictor of fat mass although we can't say that for sure. That finding echos a previous study in China where wheat eaters were more likely to be overweight than rice eaters (1, 2). Head over to Denise's post for the full story.
The China Study has major limitations built into its basic design, due to the fact that it was observational and pooled the blood samples of many individuals. Therefore, its findings can never prove anything, they can only suggest or be consistent with hypotheses. However, the study also has some unique advantages, such as a diversity of diets and regions, and the fact that people had presumably been eating a similar diet for a long time. I feel that Denise's efforts are really teasing out some useful information from the study that have been de-emphasized by other investigators.
There has been so little serious investigation into the health effects of wheat in the general population that I have to rely mostly on indirect evidence, such as the observation that the diseases of civilization tend to closely follow the introduction of white flour around the globe. Researchers studying celiac disease and other forms of gluten allergy, and the efforts of the paleolithic diet community in spreading that information (for example, Loren Cordain and Pedro Bastos), have been major contributors to understanding the health effects of wheat. Denise's analysis is one of the strongest pieces of evidence I've come by so far. One of these days, I'll post all of my references incriminating wheat. There are quite a few, although none of them is the smoking gun. I think there's enough indirect evidence that investigators should begin taking the idea seriously that wheat, particularly in the form of industrial flour products, may contribute to chronic disease in more than just a small subset of the population.
Saturated Fat, Glycemic Index and Insulin Sensitivity: Another Nail in the Coffin
Saturday, August 28, 2010 11:00 PM
Insulin is a hormone that drives glucose and other nutrients from the bloodstream into cells, among other things. A loss of sensitivity to the insulin signal, called insulin resistance, is a core feature of modern metabolic dysfunction and can lead to type II diabetes and other health problems. Insulin resistance affects a large percentage of people in affluent nations, in fact the majority of people in some places. What causes insulin resistance? Researchers have been trying to figure this out for decades.*
Since saturated fat is blamed for everything from cardiovascular disease to diabetes, it's no surprise that a number of controlled trials have asked if saturated fat feeding causes insulin resistance when compared to other fats. From the way the evidence is sometimes portrayed, you might think it does. However, a careful review of the literature reveals that this position is exaggerated, to put it mildly (1).
The glycemic index, a measure of how much a specific carbohydrate food raises blood sugar, is another darling of the diet-health literature. On the surface, it makes sense: if excess blood sugar is harmful, then foods that increase blood sugar should be harmful. Despite evidence from observational studies, controlled trials as long as 1.5 years have shown that the glycemic index does not influence insulin sensitivity or body fat gain (2, 3, 4). The observational studies may be confounded by the fact that white flour and sugar are the two main high-glycemic foods in most Western diets. Most industrially processed carbohydrate foods also have a high glycemic index, but that doesn't imply that their high glycemic index is the reason they're harmful.
All of this is easy for me to accept, because I'm familiar with examples of traditional cultures eating absurd amounts of saturated fat and/or high-glycemic carbohydrate, and not developing metabolic disease (5, 6, 7). I believe the key is that their food is not industrially processed (along with exercise, sunlight exposure, and probably other factors).
A large new study just published in the American Journal of Clinical nutrition has placed the final nail in the coffin: neither saturated fat nor high glycemic carbohydrate influence insulin sensitivity in humans, at least on the timescale of most controlled trials (8). At 6 months and 720 participants, it was both the largest and one of the longest studies to address the question. Participants were assigned to one of the following diets:
1. High saturated fat, high glycemic index
2. High monounsaturated fat, high glycemic index
3. High monounsaturated fat, low glycemic index
4. Low fat, high glycemic index
5. Low fat, low glycemic index
Compliance to the diets was pretty good. From the nature of the study design, I suspect the authors were expecting participants on diet #1 to fare the worst. They were eating a deadly combination of saturated fat and high glycemic carbohydrate! Well to everyone's dismay except cranks like me, there were no differences in insulin sensitivity between groups at 6 months. Blood pressure also didn't differ between groups, although the low-fat groups lost more weight than the monounsaturated fat groups. The investigators didn't attempt to determine whether the weight loss was fat, lean mass or both. The low-fat groups also saw an increase in the microalbumin:creatinine ratio compared to other groups, indicating a possible deterioration of kidney function.
In my opinion, the literature as a whole consistently shows that if saturated fat or high glycemic carbohydrate influence insulin sensitivity, they do so on a very long timescale, as no effect is detectable in controlled trails of fairly long duration. While it is possible that the controlled trials just didn't last long enough to detect an effect, I think it's more likely that both factors are irrelevant.
Fats were provided by the industrial manufacturer Unilever, and were incorporated into margarines, which I'm sure were just lovely to eat. Carbohydrate was also provided, including "bread, pasta, rice, and cereals." In other words, all participants were eating industrial food. I think these types of investigations often run into problems due to reductionist thinking. I prefer studies like Dr. Staffan Lindeberg's paleolithic diet trials (9, 10, 11). The key difference? They focus mostly on diet quality, not calories or specific nutrients. And they have shown that quality is king!
* Excess body fat is almost certainly a major cause. When fat mass increases beyond a certain point, particularly abdominal fat, the fat tissue typically becomes inflamed. Inflamed fat tissue secretes factors which reduce whole-body insulin sensitivity (12, 13). The big question is: what caused the fat gain?
Tropical Plant Fats: Coconut Oil, Part II
Friday, August 20, 2010 10:20 PM
Heart Disease: Animal Studies
Although humans aren't rats, animal studies are useful because they can be tightly controlled and experiments can last for a significant portion of an animal's lifespan. It's essentially impossible to do a tightly controlled 20-year feeding study in humans.
The first paper I'd like to discuss come from the lab of Dr. Thankappan Rajamohan at the university of Kerala (1). Investigators fed three groups of rats different diets:
1. Sunflower oil plus added cholesterol
2. Copra oil, a coconut oil pressed from dried coconuts, plus added cholesterol
3. Freshly pressed virgin coconut oil, plus added cholesterol
Diets 1 and 2 resulted in similar lipids, while diet 3 resulted in lower LDL and higher HDL. A second study also showed that diet 3 resulted in lower oxidized LDL, a dominant heart disease risk factor (2). Overall, these papers showed that freshly pressed virgin coconut oil, with its full complement of "minor constituents"*, partially protects rats against the harmful effects of cholesterol overfeeding. These are the only papers I could find on the cardiovascular effects of unrefined coconut oil in animals!
Although unrefined coconut oil appears to be superior, even refined coconut oil isn't as bad as it's made out to be. For example, compared to refined olive oil, refined coconut oil protects against atherosclerosis (hardening and thickening of the arteries) in a mouse model of coronary heart disease (LDL receptor knockout). In the same paper, coconut oil caused more atherosclerosis in a different mouse model (ApoE knockout) (3). So the vascular effects of coconut oil depend in part on the animals' genetic background.
In general, I've found that the data are extremely variable from one study to the next, with no consistent trend showing refined coconut oil to be protective or harmful relative to refined monounsaturated fats (like olive oil) (4). In some cases, polyunsaturated oils cause less atherosclerosis than coconut oil in the context of an extreme high-cholesterol diet because they sometimes lead to blood lipid levels that are up to 50% lower. However, even this isn't consistent across experiments. Keep in mind that atherosclerosis is only one factor in heart attack risk.
What happens if you feed coconut oil to animals without adding cholesterol, and without giving them genetic mutations that promote atherosclerosis? Again, the data are contradictory. In rabbits, one investigator showed that serum cholesterol increases transiently, returning to baseline after about 6 months, and atherosclerosis does not ensue (5). A different investigator showed that coconut oil feeding results in lower blood lipid oxidation than sunflower oil (6). Yet a study from the 1980s showed that in the context of a terrible diet composition (40% sugar, isolated casein, fat, vitamins and minerals), refined coconut oil causes elevated blood lipids and atherosclerosis (7). This is almost certainly because overall diet quality influences the response to dietary fats in rabbits, as it does in other mammals.
Heart Disease: Human Studies
It's one of the great tragedies of modern biomedical research that most studies focus on nutrients rather than foods. This phenomenon is called "nutritionism". Consequently, most of the studies on coconut oil used a refined version, because the investigators were most interested in the effect of specific fatty acids. The vitamins, polyphenols and other minor constituents of unrefined oils are eliminated because they are known to alter the biological effects of the fats themselves. Unfortunately, any findings that result from these experiments apply only to refined fats. This is the fallacy of the "X fatty acid does this and that" type statements-- they ignore the biological complexity of whole foods. They would probably be correct if you were drinking purified fatty acids from a beaker.
Generally, the short-term feeding studies using refined coconut oil show that it increases both LDL ("bad cholesterol") and HDL ("good cholesterol"), although there is so much variability between studies that it makes firm conclusions difficult to draw (8, 9). As I've written in the past, the ability of saturated fats to elevate LDL appears to be temporary; both human and certain animal studies show that it disappears on timescales of one year or longer (10, 11). That hasn't been shown specifically for coconut oil that I'm aware of, but it could be one of the reasons why traditional cultures eating high-coconut diets don't have elevated serum cholesterol.
Another marker of cardiovascular disease risk is lipoprotein (a), abbreviated Lp(a). This lipoprotein is a carrier for oxidized lipids in the blood, and it correlates with a higher risk of heart attack. Refined coconut oil appears to lower Lp(a), while refined sunflower oil increases it (12).
Unfortunately, I haven't been able to find any particularly informative studies on unrefined coconut oil in humans. The closest I found was a study from Brazil showing that coconut oil reduced abdominal obesity better than soybean oil in conjunction with a low-calorie diet, without increasing LDL (13). It would be nice to have more evidence in humans confirming what has been shown in rats that there's a big difference between unrefined and refined coconut oil.
Coconut Oil and Body Fat
In addition to the study mentioned above, a number of experiments in animals have shown that "medium-chain triglycerides", the predominant type of fat in coconut oil, lead to a lower body fat percentage than most other fats (14). These findings have been replicated numerous times in humans, although the results have not always been consistent (15). It's interesting to me that these very same medium-chain saturated fats that are being researched as a fat loss tool are also considered by mainstream diet-heart researchers to be among the most deadly fatty acids.
Coconut Oil and Cancer
Refined coconut oil produces less cancer than seed oils in experimental animals, probably because it's much lower in omega-6 polyunsaturated fat (16, 17). I haven't seen any data in humans.
The Bottom Line
There's very little known about the effect of unrefined coconut oil on animal and human health, however what is published appears to be positive, and is broadly consistent with the health of traditional cultures eating unrefined coconut foods. The data on refined coconut oil are conflicting and frustrating to sort through. The effects of refined coconut oil seem to depend highly on dietary context and genetic background. In my opinion, virgin coconut oil can be part of a healthy diet, and may even have health benefits in some contexts.
* Substances other than the fat itself, e.g. vitamin E and polyphenols. These are removed during oil refining.
Tropical Plant Fats: Coconut Oil, Part I
Friday, August 20, 2010 1:16 PM
Traditional Uses for Coconut
Coconut palms are used for a variety of purposes throughout the tropics. Here are a few quotes from the book Polynesia in Early Historic Times:
Most palms begin to produce nuts about five years after germination and continue to yield them for forty to sixty years at a continuous (i.e., nonseasonal) rate, producing about fifty nuts a year. The immature nut contains a tangy liquid that in time transforms into a layer of hard, white flesh on the inner surface of the shell and, somewhat later, a spongy mass of embryo in the nut's cavity. The liquid of the immature nut was often drunk, and the spongy embryo of the mature nut often eaten, raw or cooked, but most nuts used for food were harvested after the meat had been deposited and before the embryo had begun to form...
After the nut had been split, the most common method of extracting its hardened flesh was by scraping it out of the shell with a saw-toothed tool of wood, shell, or stone, usually lashed to a three-footed stand. The shredded meat was then eaten either raw or mixed with some starchy food and then cooked, or had its oily cream extracted, by some form of squeezing, for cooking with other foods or for cosmetic or medical uses...
Those Polynesians fortunate enough to have coconut palms utilized their components not only for drink and food-- in some places the most important, indeed life-supporting food-- but also for building-frames, thatch, screens, caulking material, containers, matting, cordage, weapons, armor, cosmetics, medicine, etc.
Mainstream Ire
Coconut fat is roughly 90 percent saturated, making it one of the most highly saturated fats on the planet. For this reason, it has been the subject of grave pronouncements by health authorities over the course of the last half century, resulting in its near elimination from the industrial food system. If the hypothesis that saturated fat causes heart disease and other health problems is correct, eating coconut oil regularly should tuck us in for a very long nap.
Coconut Eaters
As the Polynesians spread throughout the Eastern Pacific islands, they encountered shallow coral atolls that were not able to sustain their traditional starchy staples, taro, yams and breadfruit. Due to its extreme tolerance for poor, salty soils, the coconut palm was nearly the only food crop that would grow on these islands*. Therefore, their inhabitants lived almost exclusively on coconut and seafood for hundreds of years.
One group of islands that falls into this category is Tokelau, which fortunately for us was the subject of a major epidemiological study that spanned the years 1968 to 1982: the Tokelau Island Migrant Study (1). By this time, Tokelauans had managed to grow some starchy foods such as taro and breadfruit (introduced in the 20th century by Europeans), as well as obtaining some white flour and sugar, but their calories still came predominantly from coconut.
Over the time period in question, Tokelauans obtained roughly half their calories from coconut, placing them among the most extreme consumers of saturated fat in the world. Not only was their blood cholesterol lower than the average Westerner, but their hypertension rate was low, and physicians found no trace of previous heart attacks by ECG (age-adjusted rates: 0.0% in Tokelau vs 3.5% in Tecumseh USA). Migrating to New Zealand and cutting saturated fat intake in half was associated with a rise in ECG signs of heart attack (1.0% age-adjusted) (2, 3).
Diabetes was low in men and average in women by modern Western standards, but increased significantly upon migration to New Zealand and reduction of coconut intake (4). Non-migrant Tokelauans gained body fat at a slower rate than migrants, despite higher physical activity in the latter (5). Together, this evidence seriously challenges the idea that coconut is unhealthy.
The Kitavans also eat an amount of coconut fat that would make Dr. Ancel Keys blush. Dr. Staffan Lindeberg found that they got 21% of their 2,200 calories per day from fat, nearly all of which came from coconut. They were getting 17% of their calories from saturated fat; 55% more than the average American. Dr. Lindeberg's detailed series of studies found no trace of coronary heart disease or stroke, nor any obesity, diabetes or senile dementia even in the very old (6, 7).
Of course, the Tokelauans, Kitavans and other traditional cultures were not eating coconut in the form of refined, hydrogenated coconut oil cake icing. That distinction will be important when I discuss what the biomedical literature has to say in the next post.
* Most also had pandanus palms, which are also tolerant of poor soils and whose fruit provided a small amount of starch and sugar.
Can a Statin Neutralize the Cardiovascular Risk of Unhealthy Dietary Choices?
Friday, August 13, 2010 9:00 AM
The title of this post is the exact title of a recent editorial in the American Journal of Cardiology (1). Investigators calculated the "risk for cardiovascular disease associated with the total fat and trans fat content of fast foods", and compared it to the "risk decrease provided by daily statin consumption". Here's what they found:
The risk reduction associated with the daily consumption of most statins, with the exception of pravastatin, is more powerful than the risk increase caused by the daily extra fat intake associated with a 7-oz hamburger (Quarter Pounder®) with cheese and a small milkshake. In conclusion, statin therapy can neutralize the cardiovascular risk caused by harmful diet choices.
Routine accessibility of statins in establishments providing unhealthy food might be a rational modern means to offset the cardiovascular risk. Fast food outlets already offer free condiments to supplement meals. A free statin-containing accompaniment would offer cardiovascular benefits, opposite to the effects of equally available salt, sugar, and high-fat condiments. Although no substitute for systematic lifestyle improvements, including healthy diet, regular exercise, weight loss, and smoking cessation, complimentary statin packets would add, at little cost, 1 positive choice to a panoply of negative ones.
Wow. Later in the editorial, they recommend "a new and protective packet, “MacStatin,” which could be sprinkled onto a Quarter Pounder or into a milkshake." I'm not making this up!
I can't be sure, but I think there's a pretty good chance the authors were being facetious in this editorial, in which case I think a) it's hilarious, b) most people aren't going to get the joke. If they are joking, the editorial is designed to shine a light on the sad state of mainstream preventive healthcare. Rather than trying to educate people and change the deadly industrial food system, which is at the root of a constellation of health problems, many people think it's acceptable to partially correct one health risk by tinkering with the human metabolism using drugs. To be fair, most people aren't willing to change their diet and lifestyle habits (and perhaps for some it's even too late), so frustrated physicians prescribe drugs to mitigate the risk. I accept that. But if our society is really committed to its own health and well-being, we'll remove the artificial incentives that favor industrial food, and educate children from a young age on how to eat well.
I think one of the main challenges we face is that our current system is immensely lucrative for powerful financial interests. Industrial agriculture lines the pockets of a few large farmers and executives (while smaller farmers go broke and get bought out), industrial food processing concentrates profit among a handful of mega-manufacturers, and then people who are made ill by the resulting food spend an exorbitant amount of money on increasingly sophisticated (and expensive) healthcare. It's a system that effectively milks US citizens for a huge amount of money, and keeps the economy rolling at the expense of the average person's well-being. All of these groups have powerful lobbies that ensure the continuity of the current system. Litigation isn't the main reason our healthcare is so expensive in the US; high levels of chronic disease, expensive new technology, a "kitchen sink" treatment approach, and inefficient private companies are the real reasons.
If the editorial is serious, there are so many things wrong with it I don't even know where to begin. Here are a few problems:
1. They assume the risk of heart attack conveyed by eating fast food is due to its total and trans fat content, which is simplistic. To support that supposition, they cite one study: the Health Professionals Follow-up Study (2). This is one of the best diet-health observational studies conducted to date. The authors of the editorial appear not to have read the study carefully, because it found no association between total or saturated fat intake and heart attack risk, when adjusted for confounding variables. The number they quoted (relative risk = 1.23) was before adjustment for fiber intake (relative risk = 1.02 after adjustment), and in any case, it was not statistically significant even before adjustment. How did that get past peer review? Answer: reviewers aren't critical of hypotheses they like.
2. Statins mostly work in middle-aged men, and reduce the risk of heart attack by about one quarter. The authors excluded several recent unsupportive trials from their analysis. Dr. Michel de Lorgeril reviewed these trials recently (3). For these reasons, adding a statin to fast food would probably have a negligible effect on the heart attack risk of the general population.
3. "Statins rarely cause negative side effects." BS. Of the half dozen people I know who have gone on statins, all of them have had some kind of negative side effect, two of them unpleasant enough that they discontinued treatment against their doctor's wishes. Several of them who remained on statins are unlikely to benefit because of their demographic, yet they remain on statins on their doctors' advice.
4. Industrial food is probably the main contributor to heart attack risk. Cultures that don't eat industrial food are almost totally free of heart attacks, as demonstrated by a variety of high-quality studies (4, 5, 6, 7, 8, 9). No drug can replicate that, not even close.
I have an alternative proposal. Rather than giving people statins along with their Big Mac, why don't we change the incentive structure that artificially favors the Big Mac, french fries and soft drink? If it weren't for corn, soybean and wheat subsidies, fast food wouldn't be so cheap. Neither would any other processed food. Fresh, whole food would be price competitive with industrial food, particularly if we applied the grain subsidies to more wholesome foods. Grass-fed beef and dairy would cost the same as grain-fed. I'm no economist, so I don't know how realistic this really is. However, my central point still stands: we can change the incentive structure so that it no longer artificially favors industrial food. That will require that the American public get fed up and finally butt heads with special interest groups.
Saturated Fat Consumption Still isn't Associated with Cardiovascular Disease
Monday, August 09, 2010 11:19 AM
The American Journal of Clinical Nutrition just published the results of a major Japanese study on saturated fat intake and cardiovascular disease (1). Investigators measured dietary habits, then followed 58,453 men and women for 14.1 years. They found that people who ate the most saturated fat had the same heart attack risk as those who ate the least*. Furthermore, people who ate the most saturated fat had a lower risk of stroke than those who ate the least. It's notable that stroke is a larger public health threat in Japan than heart attacks.
This is broadly consistent with the rest of the observational studies examining saturated fat intake and cardiovascular disease risk. A recent review paper by Dr. Ronald Krauss's group summed up what is obvious to any unbiased person who is familiar with the literature, that saturated fat consumption doesn't associate with heart attack risk (2). In a series of editorials, some of his colleagues attempted to discredit and intimidate him after its publication (3, 4). No meta-analysis is perfect, but their criticisms were largely unfounded (5, 6).
*Actually, people who ate the most saturated fat had a lower risk but it wasn't statistically significant.
Sally Fallon Morell has invited me to give a talk on the diet and health of Pacific islanders. The talk will be titled "Kakana Dina: Diet and Health in the Pacific Islands", and it will take place on Sunday, November 14th from 4:00 to 5:20 pm. In preparation for the talk, I've read eight books and countless journal articles. Although some of the material will be familiar to people who follow the blog, I will not be rehashing what I've already published. I have nearly an hour and a half to talk, so I'll be going into some depth on the natural history and traditional food habits of Pacific island populations. Not just macronutrient breakdowns... specific foods and traditional preparation methods.
Learn about the health of traditional Pacific island populations, and what has changed since Western contact. Learn about traditional cooking and fermentation techniques. See unpublished photos from the Kitava study, courtesy of Dr. Staffan Lindeberg. Learn about the nutritional and ceremonial role of mammals including pork... and the most gruesome food of all.
I hope to see you there!
Kitava photo courtesy of Dr. Staffan Lindeberg
Dogen Zenji on Nutritionism
Sunday, September 12, 2010 3:55 AM
Dogen Zenji was the man who brought the Soto lineage of Zen Buddhism to Japan. He was a prolific writer, and many of his texts are respected both inside and outside the Soto Zen community. Last week, my Zen group was discussing the Genjo Koan, one of his works that is frequently used as a chant. Here's an excerpt. It may seem cryptic but bear with me:
...when you sail out in a boat to the middle of an ocean where no land is in sight, and view the four directions, the ocean looks circular, and does not look any other way. But the ocean is neither round or square; its features are infinite in variety... It only look circular as far as you can see at that time. All things are like this.
Though there are many features in the dusty world and the world beyond conditions, you see and understand only what your eye of practice can reach. In order to learn the nature of the myriad things, you must know that although they may look round or square, the other features of oceans and mountains are infinite in variety; whole worlds are there. It is so not only around you, but also directly beneath your feet, or in a drop of water.
What Dogen meant, among other things, is that the world is much more complex than what our conscious minds can perceive or understand. It was true in the 13th century, and it's still true today, despite our greatly expanded understanding of the natural world.
We can apply this principle to nutrition. For example, what is red palm oil? Two hundred years ago, perhaps we only knew a few basic facts about it. It's a fat, it's red, it comes from an African palm fruit and it has a particular melting point and flavor. Then we learned about vitamins, so we knew it contained vitamin E, carotenes (provitamin A), and vitamin K. Then fatty acid composition, so we found out it's mostly palmitic and oleic acids. Now we know red palm oil contains an array of polyphenols, sterols, coenzyme Q10 and many other non-essential constituents. We don't know much about the biological effects of most of these substances, particularly in combination with one another.
Add to that the fact that every batch of red palm oil is different, due to strain, terroir, processing, storage, et cetera. We know what the concept "red palm oil" means, roughly, but the details are infinitely complex. Now feed it to a human, who is not only incredibly complex himself, but genetically and epigenetically unique. How can we possibly guess the outcome of this encounter based on the chemical composition of red palm oil? That's essentially what nutritionism attempts to do.
To be fair, nutritionism does work sometimes. For example, we can pretty well guess that a handful of wild almonds containing a lot of cyanide won't be healthy to eat, due at least in part to the cyanide. But outside extreme examples like this, we're in a gray zone that needs to be informed by empirical observation. In other words, what happens when the person in question actually eats the red palm oil? What happened when a large group of people in West Africa ate red palm oil for thousands of years? Those questions are the reason why I'm so interested in understanding the lives of healthy non-industrial cultures.
I'm not criticizing reductionist science or controlled experiments (which I perform myself); I just think they need to be kept in context. I believe they should be interpreted within the framework of more basic empirical observations*.
One of the most important aspects of scientific maturity is learning to accept and manage uncertainty and your own ignorance. Some things are more certain than others, but most aren't set in stone. I think Dogen would tell us to be wary of nutritionism, and other forms of overconfidence.
* Wikipedia's definition of empirical: "information gained by means of observation, experience, or experiment." As opposed to inferences made from experiments not directly related to the question at hand.
The China Study on Wheat
Friday, September 03, 2010 12:10 PM
Denise Minger has just put up another great China Study post that's worth reading if you haven't already. Denise has been busy applying her statistics skills to the mountain of data the study collected. She noted in a previous post that wheat intake was strongly associated with coronary heart disease (CHD), the quintessential modern cardiovascular disease. I, and several other people, requested that she work her mathmagic to see if the association could be due to some other factor. For example, wheat is eaten mostly in the Northern regions of China, and CHD rates are generally higher at higher latitudes (vitamin D insufficiency?). This is true in Europe as well, and may be partly responsible for the purported benefits of the Mediterranean diet. You can mathematically determine if the association between wheat and CHD is simply due to the fact that wheat eaters live further North.
To make a long story short, nothing could explain the association except wheat itself, even latitude. Furthermore, she found a strong association between wheat intake and body mass index, typically a predictor of fat mass although we can't say that for sure. That finding echos a previous study in China where wheat eaters were more likely to be overweight than rice eaters (1, 2). Head over to Denise's post for the full story.
The China Study has major limitations built into its basic design, due to the fact that it was observational and pooled the blood samples of many individuals. Therefore, its findings can never prove anything, they can only suggest or be consistent with hypotheses. However, the study also has some unique advantages, such as a diversity of diets and regions, and the fact that people had presumably been eating a similar diet for a long time. I feel that Denise's efforts are really teasing out some useful information from the study that have been de-emphasized by other investigators.
There has been so little serious investigation into the health effects of wheat in the general population that I have to rely mostly on indirect evidence, such as the observation that the diseases of civilization tend to closely follow the introduction of white flour around the globe. Researchers studying celiac disease and other forms of gluten allergy, and the efforts of the paleolithic diet community in spreading that information (for example, Loren Cordain and Pedro Bastos), have been major contributors to understanding the health effects of wheat. Denise's analysis is one of the strongest pieces of evidence I've come by so far. One of these days, I'll post all of my references incriminating wheat. There are quite a few, although none of them is the smoking gun. I think there's enough indirect evidence that investigators should begin taking the idea seriously that wheat, particularly in the form of industrial flour products, may contribute to chronic disease in more than just a small subset of the population.
Saturated Fat, Glycemic Index and Insulin Sensitivity: Another Nail in the Coffin
Saturday, August 28, 2010 11:00 PM
Insulin is a hormone that drives glucose and other nutrients from the bloodstream into cells, among other things. A loss of sensitivity to the insulin signal, called insulin resistance, is a core feature of modern metabolic dysfunction and can lead to type II diabetes and other health problems. Insulin resistance affects a large percentage of people in affluent nations, in fact the majority of people in some places. What causes insulin resistance? Researchers have been trying to figure this out for decades.*
Since saturated fat is blamed for everything from cardiovascular disease to diabetes, it's no surprise that a number of controlled trials have asked if saturated fat feeding causes insulin resistance when compared to other fats. From the way the evidence is sometimes portrayed, you might think it does. However, a careful review of the literature reveals that this position is exaggerated, to put it mildly (1).
The glycemic index, a measure of how much a specific carbohydrate food raises blood sugar, is another darling of the diet-health literature. On the surface, it makes sense: if excess blood sugar is harmful, then foods that increase blood sugar should be harmful. Despite evidence from observational studies, controlled trials as long as 1.5 years have shown that the glycemic index does not influence insulin sensitivity or body fat gain (2, 3, 4). The observational studies may be confounded by the fact that white flour and sugar are the two main high-glycemic foods in most Western diets. Most industrially processed carbohydrate foods also have a high glycemic index, but that doesn't imply that their high glycemic index is the reason they're harmful.
All of this is easy for me to accept, because I'm familiar with examples of traditional cultures eating absurd amounts of saturated fat and/or high-glycemic carbohydrate, and not developing metabolic disease (5, 6, 7). I believe the key is that their food is not industrially processed (along with exercise, sunlight exposure, and probably other factors).
A large new study just published in the American Journal of Clinical nutrition has placed the final nail in the coffin: neither saturated fat nor high glycemic carbohydrate influence insulin sensitivity in humans, at least on the timescale of most controlled trials (8). At 6 months and 720 participants, it was both the largest and one of the longest studies to address the question. Participants were assigned to one of the following diets:
1. High saturated fat, high glycemic index
2. High monounsaturated fat, high glycemic index
3. High monounsaturated fat, low glycemic index
4. Low fat, high glycemic index
5. Low fat, low glycemic index
Compliance to the diets was pretty good. From the nature of the study design, I suspect the authors were expecting participants on diet #1 to fare the worst. They were eating a deadly combination of saturated fat and high glycemic carbohydrate! Well to everyone's dismay except cranks like me, there were no differences in insulin sensitivity between groups at 6 months. Blood pressure also didn't differ between groups, although the low-fat groups lost more weight than the monounsaturated fat groups. The investigators didn't attempt to determine whether the weight loss was fat, lean mass or both. The low-fat groups also saw an increase in the microalbumin:creatinine ratio compared to other groups, indicating a possible deterioration of kidney function.
In my opinion, the literature as a whole consistently shows that if saturated fat or high glycemic carbohydrate influence insulin sensitivity, they do so on a very long timescale, as no effect is detectable in controlled trails of fairly long duration. While it is possible that the controlled trials just didn't last long enough to detect an effect, I think it's more likely that both factors are irrelevant.
Fats were provided by the industrial manufacturer Unilever, and were incorporated into margarines, which I'm sure were just lovely to eat. Carbohydrate was also provided, including "bread, pasta, rice, and cereals." In other words, all participants were eating industrial food. I think these types of investigations often run into problems due to reductionist thinking. I prefer studies like Dr. Staffan Lindeberg's paleolithic diet trials (9, 10, 11). The key difference? They focus mostly on diet quality, not calories or specific nutrients. And they have shown that quality is king!
* Excess body fat is almost certainly a major cause. When fat mass increases beyond a certain point, particularly abdominal fat, the fat tissue typically becomes inflamed. Inflamed fat tissue secretes factors which reduce whole-body insulin sensitivity (12, 13). The big question is: what caused the fat gain?
Tropical Plant Fats: Coconut Oil, Part II
Friday, August 20, 2010 10:20 PM
Heart Disease: Animal Studies
Although humans aren't rats, animal studies are useful because they can be tightly controlled and experiments can last for a significant portion of an animal's lifespan. It's essentially impossible to do a tightly controlled 20-year feeding study in humans.
The first paper I'd like to discuss come from the lab of Dr. Thankappan Rajamohan at the university of Kerala (1). Investigators fed three groups of rats different diets:
1. Sunflower oil plus added cholesterol
2. Copra oil, a coconut oil pressed from dried coconuts, plus added cholesterol
3. Freshly pressed virgin coconut oil, plus added cholesterol
Diets 1 and 2 resulted in similar lipids, while diet 3 resulted in lower LDL and higher HDL. A second study also showed that diet 3 resulted in lower oxidized LDL, a dominant heart disease risk factor (2). Overall, these papers showed that freshly pressed virgin coconut oil, with its full complement of "minor constituents"*, partially protects rats against the harmful effects of cholesterol overfeeding. These are the only papers I could find on the cardiovascular effects of unrefined coconut oil in animals!
Although unrefined coconut oil appears to be superior, even refined coconut oil isn't as bad as it's made out to be. For example, compared to refined olive oil, refined coconut oil protects against atherosclerosis (hardening and thickening of the arteries) in a mouse model of coronary heart disease (LDL receptor knockout). In the same paper, coconut oil caused more atherosclerosis in a different mouse model (ApoE knockout) (3). So the vascular effects of coconut oil depend in part on the animals' genetic background.
In general, I've found that the data are extremely variable from one study to the next, with no consistent trend showing refined coconut oil to be protective or harmful relative to refined monounsaturated fats (like olive oil) (4). In some cases, polyunsaturated oils cause less atherosclerosis than coconut oil in the context of an extreme high-cholesterol diet because they sometimes lead to blood lipid levels that are up to 50% lower. However, even this isn't consistent across experiments. Keep in mind that atherosclerosis is only one factor in heart attack risk.
What happens if you feed coconut oil to animals without adding cholesterol, and without giving them genetic mutations that promote atherosclerosis? Again, the data are contradictory. In rabbits, one investigator showed that serum cholesterol increases transiently, returning to baseline after about 6 months, and atherosclerosis does not ensue (5). A different investigator showed that coconut oil feeding results in lower blood lipid oxidation than sunflower oil (6). Yet a study from the 1980s showed that in the context of a terrible diet composition (40% sugar, isolated casein, fat, vitamins and minerals), refined coconut oil causes elevated blood lipids and atherosclerosis (7). This is almost certainly because overall diet quality influences the response to dietary fats in rabbits, as it does in other mammals.
Heart Disease: Human Studies
It's one of the great tragedies of modern biomedical research that most studies focus on nutrients rather than foods. This phenomenon is called "nutritionism". Consequently, most of the studies on coconut oil used a refined version, because the investigators were most interested in the effect of specific fatty acids. The vitamins, polyphenols and other minor constituents of unrefined oils are eliminated because they are known to alter the biological effects of the fats themselves. Unfortunately, any findings that result from these experiments apply only to refined fats. This is the fallacy of the "X fatty acid does this and that" type statements-- they ignore the biological complexity of whole foods. They would probably be correct if you were drinking purified fatty acids from a beaker.
Generally, the short-term feeding studies using refined coconut oil show that it increases both LDL ("bad cholesterol") and HDL ("good cholesterol"), although there is so much variability between studies that it makes firm conclusions difficult to draw (8, 9). As I've written in the past, the ability of saturated fats to elevate LDL appears to be temporary; both human and certain animal studies show that it disappears on timescales of one year or longer (10, 11). That hasn't been shown specifically for coconut oil that I'm aware of, but it could be one of the reasons why traditional cultures eating high-coconut diets don't have elevated serum cholesterol.
Another marker of cardiovascular disease risk is lipoprotein (a), abbreviated Lp(a). This lipoprotein is a carrier for oxidized lipids in the blood, and it correlates with a higher risk of heart attack. Refined coconut oil appears to lower Lp(a), while refined sunflower oil increases it (12).
Unfortunately, I haven't been able to find any particularly informative studies on unrefined coconut oil in humans. The closest I found was a study from Brazil showing that coconut oil reduced abdominal obesity better than soybean oil in conjunction with a low-calorie diet, without increasing LDL (13). It would be nice to have more evidence in humans confirming what has been shown in rats that there's a big difference between unrefined and refined coconut oil.
Coconut Oil and Body Fat
In addition to the study mentioned above, a number of experiments in animals have shown that "medium-chain triglycerides", the predominant type of fat in coconut oil, lead to a lower body fat percentage than most other fats (14). These findings have been replicated numerous times in humans, although the results have not always been consistent (15). It's interesting to me that these very same medium-chain saturated fats that are being researched as a fat loss tool are also considered by mainstream diet-heart researchers to be among the most deadly fatty acids.
Coconut Oil and Cancer
Refined coconut oil produces less cancer than seed oils in experimental animals, probably because it's much lower in omega-6 polyunsaturated fat (16, 17). I haven't seen any data in humans.
The Bottom Line
There's very little known about the effect of unrefined coconut oil on animal and human health, however what is published appears to be positive, and is broadly consistent with the health of traditional cultures eating unrefined coconut foods. The data on refined coconut oil are conflicting and frustrating to sort through. The effects of refined coconut oil seem to depend highly on dietary context and genetic background. In my opinion, virgin coconut oil can be part of a healthy diet, and may even have health benefits in some contexts.
* Substances other than the fat itself, e.g. vitamin E and polyphenols. These are removed during oil refining.
Tropical Plant Fats: Coconut Oil, Part I
Friday, August 20, 2010 1:16 PM
Traditional Uses for Coconut
Coconut palms are used for a variety of purposes throughout the tropics. Here are a few quotes from the book Polynesia in Early Historic Times:
Most palms begin to produce nuts about five years after germination and continue to yield them for forty to sixty years at a continuous (i.e., nonseasonal) rate, producing about fifty nuts a year. The immature nut contains a tangy liquid that in time transforms into a layer of hard, white flesh on the inner surface of the shell and, somewhat later, a spongy mass of embryo in the nut's cavity. The liquid of the immature nut was often drunk, and the spongy embryo of the mature nut often eaten, raw or cooked, but most nuts used for food were harvested after the meat had been deposited and before the embryo had begun to form...
After the nut had been split, the most common method of extracting its hardened flesh was by scraping it out of the shell with a saw-toothed tool of wood, shell, or stone, usually lashed to a three-footed stand. The shredded meat was then eaten either raw or mixed with some starchy food and then cooked, or had its oily cream extracted, by some form of squeezing, for cooking with other foods or for cosmetic or medical uses...
Those Polynesians fortunate enough to have coconut palms utilized their components not only for drink and food-- in some places the most important, indeed life-supporting food-- but also for building-frames, thatch, screens, caulking material, containers, matting, cordage, weapons, armor, cosmetics, medicine, etc.
Mainstream Ire
Coconut fat is roughly 90 percent saturated, making it one of the most highly saturated fats on the planet. For this reason, it has been the subject of grave pronouncements by health authorities over the course of the last half century, resulting in its near elimination from the industrial food system. If the hypothesis that saturated fat causes heart disease and other health problems is correct, eating coconut oil regularly should tuck us in for a very long nap.
Coconut Eaters
As the Polynesians spread throughout the Eastern Pacific islands, they encountered shallow coral atolls that were not able to sustain their traditional starchy staples, taro, yams and breadfruit. Due to its extreme tolerance for poor, salty soils, the coconut palm was nearly the only food crop that would grow on these islands*. Therefore, their inhabitants lived almost exclusively on coconut and seafood for hundreds of years.
One group of islands that falls into this category is Tokelau, which fortunately for us was the subject of a major epidemiological study that spanned the years 1968 to 1982: the Tokelau Island Migrant Study (1). By this time, Tokelauans had managed to grow some starchy foods such as taro and breadfruit (introduced in the 20th century by Europeans), as well as obtaining some white flour and sugar, but their calories still came predominantly from coconut.
Over the time period in question, Tokelauans obtained roughly half their calories from coconut, placing them among the most extreme consumers of saturated fat in the world. Not only was their blood cholesterol lower than the average Westerner, but their hypertension rate was low, and physicians found no trace of previous heart attacks by ECG (age-adjusted rates: 0.0% in Tokelau vs 3.5% in Tecumseh USA). Migrating to New Zealand and cutting saturated fat intake in half was associated with a rise in ECG signs of heart attack (1.0% age-adjusted) (2, 3).
Diabetes was low in men and average in women by modern Western standards, but increased significantly upon migration to New Zealand and reduction of coconut intake (4). Non-migrant Tokelauans gained body fat at a slower rate than migrants, despite higher physical activity in the latter (5). Together, this evidence seriously challenges the idea that coconut is unhealthy.
The Kitavans also eat an amount of coconut fat that would make Dr. Ancel Keys blush. Dr. Staffan Lindeberg found that they got 21% of their 2,200 calories per day from fat, nearly all of which came from coconut. They were getting 17% of their calories from saturated fat; 55% more than the average American. Dr. Lindeberg's detailed series of studies found no trace of coronary heart disease or stroke, nor any obesity, diabetes or senile dementia even in the very old (6, 7).
Of course, the Tokelauans, Kitavans and other traditional cultures were not eating coconut in the form of refined, hydrogenated coconut oil cake icing. That distinction will be important when I discuss what the biomedical literature has to say in the next post.
* Most also had pandanus palms, which are also tolerant of poor soils and whose fruit provided a small amount of starch and sugar.
Can a Statin Neutralize the Cardiovascular Risk of Unhealthy Dietary Choices?
Friday, August 13, 2010 9:00 AM
The title of this post is the exact title of a recent editorial in the American Journal of Cardiology (1). Investigators calculated the "risk for cardiovascular disease associated with the total fat and trans fat content of fast foods", and compared it to the "risk decrease provided by daily statin consumption". Here's what they found:
The risk reduction associated with the daily consumption of most statins, with the exception of pravastatin, is more powerful than the risk increase caused by the daily extra fat intake associated with a 7-oz hamburger (Quarter Pounder®) with cheese and a small milkshake. In conclusion, statin therapy can neutralize the cardiovascular risk caused by harmful diet choices.
Routine accessibility of statins in establishments providing unhealthy food might be a rational modern means to offset the cardiovascular risk. Fast food outlets already offer free condiments to supplement meals. A free statin-containing accompaniment would offer cardiovascular benefits, opposite to the effects of equally available salt, sugar, and high-fat condiments. Although no substitute for systematic lifestyle improvements, including healthy diet, regular exercise, weight loss, and smoking cessation, complimentary statin packets would add, at little cost, 1 positive choice to a panoply of negative ones.
Wow. Later in the editorial, they recommend "a new and protective packet, “MacStatin,” which could be sprinkled onto a Quarter Pounder or into a milkshake." I'm not making this up!
I can't be sure, but I think there's a pretty good chance the authors were being facetious in this editorial, in which case I think a) it's hilarious, b) most people aren't going to get the joke. If they are joking, the editorial is designed to shine a light on the sad state of mainstream preventive healthcare. Rather than trying to educate people and change the deadly industrial food system, which is at the root of a constellation of health problems, many people think it's acceptable to partially correct one health risk by tinkering with the human metabolism using drugs. To be fair, most people aren't willing to change their diet and lifestyle habits (and perhaps for some it's even too late), so frustrated physicians prescribe drugs to mitigate the risk. I accept that. But if our society is really committed to its own health and well-being, we'll remove the artificial incentives that favor industrial food, and educate children from a young age on how to eat well.
I think one of the main challenges we face is that our current system is immensely lucrative for powerful financial interests. Industrial agriculture lines the pockets of a few large farmers and executives (while smaller farmers go broke and get bought out), industrial food processing concentrates profit among a handful of mega-manufacturers, and then people who are made ill by the resulting food spend an exorbitant amount of money on increasingly sophisticated (and expensive) healthcare. It's a system that effectively milks US citizens for a huge amount of money, and keeps the economy rolling at the expense of the average person's well-being. All of these groups have powerful lobbies that ensure the continuity of the current system. Litigation isn't the main reason our healthcare is so expensive in the US; high levels of chronic disease, expensive new technology, a "kitchen sink" treatment approach, and inefficient private companies are the real reasons.
If the editorial is serious, there are so many things wrong with it I don't even know where to begin. Here are a few problems:
1. They assume the risk of heart attack conveyed by eating fast food is due to its total and trans fat content, which is simplistic. To support that supposition, they cite one study: the Health Professionals Follow-up Study (2). This is one of the best diet-health observational studies conducted to date. The authors of the editorial appear not to have read the study carefully, because it found no association between total or saturated fat intake and heart attack risk, when adjusted for confounding variables. The number they quoted (relative risk = 1.23) was before adjustment for fiber intake (relative risk = 1.02 after adjustment), and in any case, it was not statistically significant even before adjustment. How did that get past peer review? Answer: reviewers aren't critical of hypotheses they like.
2. Statins mostly work in middle-aged men, and reduce the risk of heart attack by about one quarter. The authors excluded several recent unsupportive trials from their analysis. Dr. Michel de Lorgeril reviewed these trials recently (3). For these reasons, adding a statin to fast food would probably have a negligible effect on the heart attack risk of the general population.
3. "Statins rarely cause negative side effects." BS. Of the half dozen people I know who have gone on statins, all of them have had some kind of negative side effect, two of them unpleasant enough that they discontinued treatment against their doctor's wishes. Several of them who remained on statins are unlikely to benefit because of their demographic, yet they remain on statins on their doctors' advice.
4. Industrial food is probably the main contributor to heart attack risk. Cultures that don't eat industrial food are almost totally free of heart attacks, as demonstrated by a variety of high-quality studies (4, 5, 6, 7, 8, 9). No drug can replicate that, not even close.
I have an alternative proposal. Rather than giving people statins along with their Big Mac, why don't we change the incentive structure that artificially favors the Big Mac, french fries and soft drink? If it weren't for corn, soybean and wheat subsidies, fast food wouldn't be so cheap. Neither would any other processed food. Fresh, whole food would be price competitive with industrial food, particularly if we applied the grain subsidies to more wholesome foods. Grass-fed beef and dairy would cost the same as grain-fed. I'm no economist, so I don't know how realistic this really is. However, my central point still stands: we can change the incentive structure so that it no longer artificially favors industrial food. That will require that the American public get fed up and finally butt heads with special interest groups.
Saturated Fat Consumption Still isn't Associated with Cardiovascular Disease
Monday, August 09, 2010 11:19 AM
The American Journal of Clinical Nutrition just published the results of a major Japanese study on saturated fat intake and cardiovascular disease (1). Investigators measured dietary habits, then followed 58,453 men and women for 14.1 years. They found that people who ate the most saturated fat had the same heart attack risk as those who ate the least*. Furthermore, people who ate the most saturated fat had a lower risk of stroke than those who ate the least. It's notable that stroke is a larger public health threat in Japan than heart attacks.
This is broadly consistent with the rest of the observational studies examining saturated fat intake and cardiovascular disease risk. A recent review paper by Dr. Ronald Krauss's group summed up what is obvious to any unbiased person who is familiar with the literature, that saturated fat consumption doesn't associate with heart attack risk (2). In a series of editorials, some of his colleagues attempted to discredit and intimidate him after its publication (3, 4). No meta-analysis is perfect, but their criticisms were largely unfounded (5, 6).
*Actually, people who ate the most saturated fat had a lower risk but it wasn't statistically significant.
Parkour Visions Summit and Talk
On August 13-15th, my friends Rafe Kelley and Tyson Cecka are hosting a parkour summit at their Seattle gym Parkour Visions. For those of you not familiar with the sport, here's a description from the Parkour Visions site:
"The essence of Parkour can be stated simply: it is the art of overcoming obstacles as swiftly and efficiently as possible using only your body. The fundamentals include running, jumping, and climbing, and we build on these fundamentals to improve our ability to pass over, under, around and through obstacles with more complex movements. Parkour is a system of fitness training that improves strength, speed, agility, co-ordination, stamina, endurance, and precision. It offers a full-body workout at any level of experience, and improves your ability to move, to harness your confidence, to change how you see the world. Parkour practitioners are called traceurs."
The summit will include seminars on strength training, injury prevention and rehab, and nutrition, as well as parkour jams, a roundtable and a dinner. I'll be giving a talk titled "Natural Eating for Sustainable Athletic Performance" on Saturday, August 14 from noon to 1:00 pm.
Registration is $40 for the whole summit. You can read a description of it here, and find a link to the registration system at the bottom of this page.
"The essence of Parkour can be stated simply: it is the art of overcoming obstacles as swiftly and efficiently as possible using only your body. The fundamentals include running, jumping, and climbing, and we build on these fundamentals to improve our ability to pass over, under, around and through obstacles with more complex movements. Parkour is a system of fitness training that improves strength, speed, agility, co-ordination, stamina, endurance, and precision. It offers a full-body workout at any level of experience, and improves your ability to move, to harness your confidence, to change how you see the world. Parkour practitioners are called traceurs."
The summit will include seminars on strength training, injury prevention and rehab, and nutrition, as well as parkour jams, a roundtable and a dinner. I'll be giving a talk titled "Natural Eating for Sustainable Athletic Performance" on Saturday, August 14 from noon to 1:00 pm.
Registration is $40 for the whole summit. You can read a description of it here, and find a link to the registration system at the bottom of this page.
Real Food XI: Sourdough Buckwheat Crepes
Buckwheat isn't a grain: it's a 'pseudograin' that comes from a broad-leaved plant. As such, it's not related to wheat and contains no allergenic gluten. Like quinoa, it has some unusual properties that make it a particularly nutritious food. It's about 16 percent protein by calories, ranking it among the highest protein grains. However, it has an advantage over grains: it contains complete protein, meaning it has a balance of essential amino acids similar to animal foods. Buckwheat is also an exceptional source of magnesium and copper, two important nutrients that may influence the risk of insulin resistance and cardiovascular disease (1, 2).
However, like all seeds (including grains and nuts), buckwheat is rich in phytic acid. Phyic acid complexes with certain minerals, preventing their absorption by the human digestive tract. This is one of the reasons why traditional cultures prepare their grains carefully (3). During soaking, and particularly fermentation of raw batters, an enzyme called phytase goes to work breaking down the phytic acid. Not all seeds are endowed with enough phytase to break down phytic acid in a short period of time. Buckwheat contains a lot of phytase, and consequently fermented buckwheat batters contain very little phytic acid (4, 5). It's also high in astringent tannins, but thorough soaking in a large volume of water removes them.
Buckwheat is fermented in a number of traditional cultures. In Bhutan, it's fermented to make flatbreads and alcoholic drinks (6). In Brittany (Bretagne; Northwestern France), sourdough buckwheat flour pancakes are traditional. Originally a poverty food, it is now considered a delicacy.
The following simple recipe is based on my own experimentation with buckwheat. It isn't traditional as far as I know, however it is based on traditional methods used to produce sourdough flatbreads in a number of cultures. I used the word 'crepe' to describe it, but I typically make something more akin to a savory pancake or uttapam. You can use it to make crepes if you wish, but this recipe is not for traditional French buckwheat crepes.
It's important that the buckwheat be raw and whole for this recipe. Raw buckwheat is light green to light brown (as in the photo above). Kasha is toasted buckwheat, and will not substitute properly. It's also important that the water be dechlorinated and the salt non-iodized, as both will interfere with fermentation.
For a fermentation starter, you can use leftover batter from a previous batch (although it doesn't keep very long), or rice soaking water from this method (7).
Ingredients and Materials
* 2-3 cups raw buckwheat groats
* Dechlorinated water (filtered, boiled, or rested uncovered overnight)
* Non-iodized salt (sea salt, pickling salt or kosher salt), 2/3 tsp per cup of buckwheat
* Fermentation starter (optional), 2 tablespoons
* Food processor or blender
Recipe
1. Cover buckwheat with a large amount of dechlorinated water and soak for 9-24 hours. Raw buckwheat is astringent due to water-soluble tannins. Soaking in a large volume of water and giving it a stir from time to time will minimize this. The soaking water will also get slimy. This is normal.
2. Pour off the soaking water and rinse the buckwheat thoroughly to get rid of the slime and residual tannins.
3. Blend the buckwheat, salt, dechlorinated water and fermentation starter in a food processor or blender. Add enough water so that it reaches the consistency of pancake batter. The smoother you get the batter, the better the final product will be.
4. Ferment for about 12 hours, a bit longer or shorter depending on the temperature and whether or not you used a starter. The batter may rise a little bit as the microorganisms get to work. The smell will mellow out. Refrigerate it after fermentation.
5. In a greased or non-stick skillet, cook the batter at whatever thickness and temperature you prefer. I like to cook a thick 'pancake' with the lid on, at very low heat, so that it steams gently.
Dig in! Its mild flavor goes with almost anything. Batter will keep for about four days in the fridge.
Thanks to Christaface for the CC licensed photo (Flickr).
Minger Responds to Campbell
Sunday, July 18, 2010 12:17 PM
Hot off the presses: Dr. Colin Campbell's response to Denise Minger's China Study posts, and Minger's retort:
A Challenge and Response to the China Study
The China Study: My Response to Campbell
This is required reading for anyone who wants to evaluate Dr. Campbell's claims about the China Study data. Denise points out that Dr. Campbell's claims rest mostly on uncorrected associations, which is exactly what he was accusing Minger, Chris Masterjohn and Anthony Colpo of doing. He also appears to have selectively reported data that support his philosophy, and ignored data that didn't, even when the latter were stronger. This is true both in Dr. Campbell's book, and in his peer-reviewed papers. This type of thing is actually pretty common in the diet-health literature.
I respect everyone's food choices, whether they're omnivores, carnivores, or raw vegans, as long as they're doing it in a way that's thoughtful toward other people, animals and the environment. I'm sure there are plenty of vegans out there who are doing it gracefully, not spamming non-vegan blogs with arrogant comments.
As human beings, we're blessed and cursed with an ego, which is basically a self-esteem and self-image reinforcement machine. Since being wrong hurts our self-esteem and self-image, the ego makes us think we're right about more than we actually are. That can take the form of elaborate justifications, and the more intelligent the person, the more elaborate the justifications. An economic policy that makes you richer becomes the best way to improve everyone's bottom line. A dietary philosophy that was embraced for humane reasons becomes the path to optimum health... such is the human mind. Science is basically an attempt to remove as much of this psychic distortion as possible from an investigation. Ultimately, the scientific method requires rigorous and vigilant stewardship to achieve what it was designed to do.
China Study Problems of Interpretation
Friday, July 09, 2010 1:19 AM
The China study was an observational study that collected a massive amount of information about diet and health in 65 different rural regions of China. It's been popularized by Dr. T. Colin Campbell, who has argued that the study shows that plant foods are generally superior to animal foods for health, and even a small amount of animal food is harmful. Campbell's book has been at the center of the strict vegetarian (vegan) movement since its publication.
Richard from Free the Animal just passed on some information that many of you may find interesting. A woman named Denise Minger recently published a series of posts on the China study. She looked up the raw data and applied statistics to it. It's the most thorough review of the data I've seen so far. She raises some points about Campbell's interpretation of the data that are frankly disturbing. As I like to say, the problem is usually not in the data-- it's in the interpretation.
One of the things Minger points out is that wheat intake had a massive correlation with coronary heart disease-- one of the strongest correlations the investigators found. Is that because wheat causes CHD, or is it because wheat eating regions tend to be further North and thus have worse vitamin D status? I don't know, but it's an interesting observation nevertheless. Check out Denise Minger's posts... if you have the stamina:
The China Study: Fact or Fallacy
Also, see posts on the China study by Richard Nikoley, Chris Masterjohn and Anthony Colpo:
T. Colin Campbell's the China Study
The Truth About the China Study
The China Study: More Vegan Nonsense
And my previous post on the association between wheat intake and obesity in China:
Wheat in China
Tropical Plant Fats: Palm Oil
Sunday, July 04, 2010 8:32 AM
A Fatal Case of Nutritionism
The concept of 'nutritionism' was developed by Dr. Gyorgy Scrinis and popularized by the food writer Michael Pollan. It states that the health value of a food can be guessed by the sum of the nutrients it contains. Pollan argues, I think rightfully, that nutritionism is a reductionist philosophy that assumes we know more about food composition and the human body than we actually do. You can find varying degrees of this philosophy in most mainstream discussions of diet and health*.
One conspicuous way nutritionism manifests is in the idea that saturated fat is harmful. Any fat rich in saturated fatty acids is typically assumed to be unhealthy, regardless of its other constituents. There is also apparently no need to directly test that assumption, or even to look through the literature to see if the assumption has already been tested. In this manner, 'saturated' tropical plant fats such as palm oil and coconut oil have been labeled unhealthy, despite essentially no direct evidence that they're harmful. As we'll see, there is actually quite a bit of evidence, both indirect and direct, that their unrefined forms are not harmful and perhaps even beneficial.
Palm Oil and Heart Disease
Long-time readers may recall a post I wrote a while back titled Ischemic Heart Attacks: Disease of Civilization (1). I described a study from 1964 in which investigators looked for signs of heart attacks in thousands of consecutive autopsies in the US and Africa, among other places. They found virtually none in hearts from Nigeria and Uganda (3 non-fatal among more than 4,500 hearts), while Americans of the same age had very high rates (up to 1/3 of hearts).
What do they eat in Nigeria? Typical Nigerian food involves home-processed grains, starchy root vegetables, beans, fruit, vegetables, peanuts, red palm oil, and a bit of dairy, fish and meat**. The oil palm Elaeis guineensis originated in West Africa and remains one of the main dietary fats throughout the region.
To extract the oil, palm fruit are steamed, and the oily flesh is removed and pressed. It's similar to olive oil in that it is extracted gently from an oil-rich fruit, rather than harshly from an oil-poor seed (e.g., corn or soy oil). The oil that results is deep red and is perhaps the most nutrient-rich fat on the planet. The red color comes from carotenes, but red palm oil also contains a large amount of vitamin E (mostly tocotrienols), vitamin K1, coenzyme Q10 and assorted other fat-soluble constituents. This adds up to a very high concentration of fat-soluble antioxidants, which are needed to protect the fat from rancidity in hot and sunny West Africa. Some of these make it into the body when it's ingested, where they appear to protect the body's own fats from oxidation.
Mainstream nutrition authorities state that palm oil should be avoided due to the fact that it's approximately half saturated. This is actually one of the main reasons palm oil was replaced by hydrogenated seed oils in the processed food industry. Saturated fat raises blood cholesterol, which increases the risk of heart disease. Doesn't it? Let's see what the studies have to say.
Most of the studies were done using refined palm oil, unfortunately. Besides only being relevant to processed foods, this method also introduces a new variable because palm oil can be refined and oxidized to varying degrees. However, a few studies were done with red palm oil, and one even compared it to refined palm oil. Dr. Suzanna Scholtz and colleagues put 59 volunteers on diets predominating in sunflower oil, refined palm oil or red palm oil for 4 weeks. LDL cholesterol was not different between the sunflower oil and red palm oil groups, however the red palm oil group saw a significant increase in HDL. LDL and HDL both increased in the refined palm oil group relative to the sunflower oil group (2).
Although the evidence is conflicting, most studies have not been able to replicate the finding that refined palm oil increases LDL relative to less saturated oils (3, 4). This is consistent with studies in a variety of species showing that saturated fat generally doesn't raise LDL compared to monounsaturated fat in the long term, unless a large amount of purified cholesterol is added to the diet (5).
Investigators have also explored the ability of palm oil to promote atherosclerosis, or hardening and thickening of the arteries, in animals. Not only does palm oil not promote atherosclerosis relative to monounsaturated fats (e.g., olive oil), but in its unrefined state it actually protects against atherosclerosis (6, 7). A study in humans hinted at a possible explanation: compared to a monounsaturated oil***, palm oil greatly reduced oxidized LDL (8). As a matter of fact, I've never seen a dietary intervention reduce oxLDL to that degree (69%). oxLDL is a major risk factor for cardiovascular disease, and a much better predictor of risk than the typically measured LDL cholesterol (9). The paper didn't state whether or not the palm oil was refined. I suspect it was lightly refined, but still rich in vitamin E and CoQ10.
As I discussed in my recent interview with Jimmy Moore, atherosclerosis is only one factor in heart attack risk (10). Several other factors are also major determinants of risk: clotting tendency, plaque stability, and susceptibility to arrhythmia. Another factor that I haven't discussed is how resistant the heart muscle is to hypoxia, or loss of oxygen. If the coronary arteries are temporarily blocked-- a frequent occurrence in modern people-- the heart muscle can be damaged. Dietary factors determine the degree of damage that results. For example, in rodents, nitrites derived from green vegetables protect the heart from hypoxia damage (11). It turns out that red palm oil is also protective (12, 13). Red palm oil also protects against high blood pressure in rats, an effect attributed to its ability to reduce oxidative stress (14, 15).
Together, the evidence suggests that red palm oil does not contribute to heart disease risk, and in fact is likely to be protective. The benefits of red palm oil probably come mostly from its minor constituents, i.e. the substances besides its fatty acids. Several studies have shown that a red palm oil extract called palmvitee lowers serum lipids in humans (16, 17). The minor constituents are precisely what are removed during the refining process.
Palm Oil and the Immune System
Red palm oil also has beneficial effects on the immune system in rodents. It protects against bacterial infection when compared with soybean oil (18). It also protects against certain cancers, compared to other oils (19, 20). This may be in part due to its lower content of omega-6 linoleic acid (roughly 10%), and minor constituents.
The Verdict
Yet again, nutritionism has gotten itself into trouble by underestimating the biological complexity of a whole food. Rather than being harmful to human health, red palm oil, an ancient and delicious food, is likely to be protective. It's also one of the cheapest oils available worldwide, due to the oil palm's high productivity. It has a good shelf life and does not require refrigeration. Its strong, savory flavor goes well in stews, particularly meat stews. It isn't available in most grocery stores, but you can find it on the internet. Make sure not to confuse it with refined palm oil or palm kernel oil.
* The approach that Pollan and I favor is a simpler, more empirical one: eat foods that have successfully sustained healthy cultures.
** Some Nigerians are also pastoralists that subsist primarily on dairy.
*** High oleic sunflower oil, from a type of sunflower bred to be high in monounsaturated fat and low in linoleic acid. I think it's probably among the least harmful refined oils. I use it sometimes to make mayonnaise. It's often available in grocery stores, just check the label.
Interview with Jimmy Moore
Friday, June 25, 2010 8:30 AM
About two months ago, I did an interview with Jimmy Moore of the Livin' la Vida Low Carb internet empire. I hardly remember what we talked about, but I think it went well. I enjoyed Jimmy's pleasant and open-minded attitude. Head over to Jimmy's website and listen to the interview here.
I do recall making at least one mistake. When discussing heart attacks,I said "atrial fibrillation" when I meant "ventricular fibrillation".
In Search of Traditional Asian Diets
Wednesday, June 23, 2010 8:04 AM
It's been difficult for me to find good information on Asian diets prior to modernization. Traditional Chinese, Taiwanese and Japanese diets are sometimes portrayed as consisting mostly of white rice, with vegetables and a bit of meat and soy, but I find that implausible. Rice doesn't grow everywhere, in part because it requires a tremendous amount of water. Removing all the bran was prohibitively labor-intensive before the introduction of modern machine milling. One hundred years ago, bran was partially removed by beating or grinding in a mortar and pestle, as it still is in parts of rural Asia today. Only the wealthy could afford true white rice.
Given the difficulty of growing rice in most places, and hand milling it, the modern widespread consumption of white rice in Asia must be a 20th century phenomenon, originating in the last 20-100 years depending on location. Therefore, white rice consumption does not predate the emergence of the "diseases of civilization" in Asia.
In the book Western Diseases: Their Emergence and Prevention, there are several accounts of traditional Asian diets I find interesting.
Taiwan in 1980
The staple constituent of the diet is polished white rice. Formerly in the poorer areas along the sea coast the staple diet was sweet potato, with small amounts of white rice added. Formerly in the mountains sweet potato, millet and taro were the staple foods. During the last 15 years, with the general economic development of the whole island, white polished rice has largely replaced other foods. There is almost universal disinclination to eat brown (unpolished) rice, because white rice is more palatable, it bears kudos, cooking is easier and quicker, and it can be stored for a much longer period.
Traditionally, coronary heart disease and high blood pressure were rare, but the prevalence is now increasing rapidly. Stroke is common. Diabetes was rare but is increasing gradually.
Mainland China
China is a diverse country, and the food culture varies by region.
Snapper (1965)… quoted an analysis by Guy and Yeh of Peiping (Peking) diets in 1938. There was a whole cereal/legume/vegetable diet for poorer people and a milled-cereal/meat/vegetable diet for the richer people.
Symptoms of vitamin A, C and D deficiency were common in the poor, although coronary heart disease and high blood pressure were rare. Diabetes occurred at a higher rate than in most traditionally-living populations.
Japan
On the Japanese island of Okinawa, the traditional staple is the sweet potato, with a smaller amount of rice eaten as well. Seafood, vegetables, pork and soy are also on the menu. In Akira Kurosawa’s movie Seven Samurai, set in 16th century mainland Japan, peasants ate home-processed millet and barley, while the wealthy ate white rice. Although a movie may not be the best source of information, I assume it has some basis in fact.
White Rice: a Traditional Asian Staple?
It depends on your perspective. How far back do you have to go before you can call a food traditional? Many peoples' grandparents ate white rice, but I doubt their great great grandparents ate it frequently. White rice may have been a staple for the wealthy for hundreds of years in some places. But for most of Asia, in the last few thousand years, it was probably a rare treat. The diet most likely resembled that of many non-industrial Africans: an assortment of traditionally prepared grains, root vegetables, legumes, vegetables and a little meat.
Please add any additional information you may have about traditional Asian diets to the comments section.
Low Micronutrient Intake may Contribute to Obesity
Thursday, June 17, 2010 1:20 PM
Lower Micronutrient Status in the Obese
Investigators have noted repeatedly that obese people have a lower blood concentration of a number of nutrients, including vitamin A, vitamin D, vitamin K, several B vitamins, zinc and iron (1). Although there is evidence that some of these may influence fat mass in animals, the evidence for a cause-and-effect relationship in humans is generally slim. There is quite a bit of indirect evidence that vitamin D status influences the risk of obesity (2), although a large, well-controlled study found that high-dose vitamin D3 supplementation does not cause fat loss in overweight and obese volunteers over the course of a year (3). It may still have a preventive effect, or require a longer timescale, but that remains to be determined.
Hot off the Presses
A new study in the journal Obesity, by Y. Li and colleagues, showed that compared to a placebo, a low-dose multivitamin caused obese volunteers to lose 7 lb (3.2 kg) of fat mass in 6 months, mostly from the abdominal region (4). The supplement also reduced LDL by 27%, increased HDL by a whopping 40% and increased resting energy expenditure. Here's what the supplement contained:
Vitamin A(containing natural mixed b-carotene) 5000 IU
Vitamin D 400 IU
Vitamin E 30 IU
Thiamin 1.5 mg
Riboflavin 1.7 mg
Vitamin B6 2 mg
Vitamin C 60 mg
Vitamin B12 6 mcg
Vitamin K1 25 mcg
Biotin 30 mcg
Folic acid 400 mcg
Nicotinamide 20 mg
Pantothenic acid 10 mg
Calcium 162 mg
Phosphorus 125 mg
Chlorine 36.3 mg
Magnesium 100 mg
Iron 18 mg
Copper 2 mg
Zinc 15 mg
Manganese 2.5 mg
Iodine 150 mcg
Chromium 25 mcg
Molybdenum 25 mcg
Selenium 25 mcg
Nickel 5 mcg
Stannum 10 mcg
Silicon 10 mcg
Vanadium 10 mcg
Although the result needs to be repeated, if we take it at face value, it has some important implications:
* The nutrient density of a diet may influence obesity risk, as I speculated in my recent audio interview and related posts (5, 6, 7, 8, 9).
* Many nutrients act together to create health, and multiple insufficiencies may contribute to disease. This may be why single nutrient supplementation trials usually don't find much.
* Another possibility is that obesity can result from a number of different nutrient insufficiencies, and the cause is different in different people. This study may have seen a large effect because it corrected many different insufficiencies.
* This result, once again, kills the simplistic notion that body fat is determined exclusively by voluntary food consumption and exercise behaviors (sometimes called the "calories in, calories out" idea, or "gluttony and sloth"). In this case, a multivitamin was able to increase resting energy expenditure and cause fat loss without any voluntary changes in food intake or exercise, suggesting metabolic effects and a possible downward shift of the body fat "setpoint" due to improved nutrient status.
Practical Implications
Does this mean we should all take multivitamins to stay or become thin? No. There is no multivitamin that can match the completeness and balance of a nutrient-dense, whole food, omnivorous diet. Beef liver, leafy greens and sunlight are nature's vitamin pills. Avoiding refined foods instantly doubles the micronutrient content of the typical diet. Properly preparing whole grains by soaking and fermentation is equivalent to taking a multi-mineral along with conventionally prepared grains, as absorption of key minerals is increased by 50-300% (10). Or you can eat root vegetables instead of grains, and enjoy their naturally high mineral availability. Or both.
New Layout
Tuesday, June 15, 2010 10:47 AM
I thought I'd spruce the place up a bit! Let me know what you think in the comments.
Nitrate: a Protective Factor in Leafy Greens
Tuesday, June 15, 2010 9:51 AM
Cancer Link and Food Sources
Nitrate (NO3) is a molecule that has received a lot of bad press over the years. It was initially thought to promote digestive cancers, in part due to its ability to form carcinogens in the digestive tract. As it's used as a preservative in processed meats, and there is a link between processed meats and gastric cancer (1), nitrate was viewed with suspicion and a number of countries imposed strict limits on its use as a food additive.
But what if I told you that by far the greatest source of nitrate in the modern diet isn't processed meat-- but vegetables, particularly leafy greens (2)? And that the evidence specifically linking nitrate consumption to gastric cancer has largely failed to materialize? For example, one study found no difference in the incidence of gastric cancer between nitrate fertilizer plant workers and the general population (3). Most other studies in animals and humans have not supported the hypothesis that nitrate itself is carcinogenic (4, 5, 6). This, combined with recent findings on nitrate biology, has the experts singing a different tune in the last few years.
A New Example of Human Symbiosis
In 2003, Dr. K. Cosby and colleagues showed that nitrite (NO2; not the same as nitrate) dilates blood vessels in humans when infused into the blood (7). Investigators subsequently uncovered an amazing new example of human-bacteria symbiosis: dietary nitrate (NO3) is absorbed from the gut into the bloodstream and picked up by the salivary glands. It's then secreted into saliva, where oral bacteria use it as an energy source, converting it to nitrite (NO2). After swallowing, the nitrite is reabsorbed into the bloodstream (8). Humans and oral bacteria may have co-evolved to take advantage of this process. Antibacterial mouthwash prevents it.
Nitrate Protects the Cardiovascular System
In 2008, Dr. Andrew J. Webb and colleagues showed that nitrate in the form of 1/2 liter of beet juice (equivalent in volume to about 1.5 soda cans) substantially lowers blood pressure in healthy volunteers for over 24 hours. It also preserved blood vessel performance after brief oxygen deprivation, and reduced the tendency of the blood to clot (9). These are all changes that one would expect to protect against cardiovascular disease. Another group showed that in monkeys, the ability of nitrite to lower blood pressure did not diminish after two weeks, showing that the animals did not develop a tolerance to it on this timescale (10).
Subsequent studies showed that dietary nitrite reduces blood vessel dysfunction and inflammation (CRP) in cholesterol-fed mice (11). Low doses of nitrite also dramatically reduce tissue death in the hearts of mice exposed to conditions mimicking a heart attack, as well as protecting other tissues against oxygen deprivation damage (12). The doses used in this study were the equivalent of a human eating a large serving (100 g; roughly 1/4 lb) of lettuce or spinach.
Mechanism
Nitrite is thought to protect the cardiovascular system by serving as a precursor for nitric oxide (NO), one of the most potent anti-inflammatory and blood vessel-dilating compounds in the body (13). A decrease in blood vessel nitric oxide is probably one of the mechanisms of diet-induced atherosclerosis and increased clotting tendency, and it is likely an early consequence of eating a poor diet (14).
The Long View
Leafy greens were one of the "protective foods" emphasized by the nutrition giant Sir Edward Mellanby (15), along with eggs and high-quality full-fat dairy. There are many reasons to believe greens are an excellent contribution to the human diet, and what researchers have recently learned about nitrate biology certainly reinforces that notion. Leafy greens may be particularly useful for the prevention and reversal of cardiovascular disease, but are likely to have positive effects on other organ systems both in health and disease. It's ironic that a molecule suspected to be the harmful factor in processed meats is turning out to be one of the major protective factors in vegetables.
Fermented Grain Recipes from Around the World
Thursday, June 10, 2010 4:56 AM
In my last two posts on grains, I described how traditional food processing methods make grains more nutritious and digestible (1, 2). I promised to briefly describe a few recipes from around the world, then got distracted by other things. Here they are.
Africa: Ogi
Grain fermentation is widespread in Africa and is probably nearly as old as agriculture on the continent. The nutritional importance of fermentation is suggested by the amount of time and effort that many African cultures put into it, when they could save themselves a lot of trouble by simply soaking and cooking their grains.
Ogi is a common West African porridge that's eaten as a staple food by people of all ages. It's even used as a weaning food. It's made in essentially the same manner from corn, sorghum or millet.
Whole grain is soaked in water for one to three days. It's then wet milled, mixed with water and sieved to remove a portion of the bran. Extra bran is fed to animals, while the white, starchy sediment is fermented for two to three days. This is then cooked into a thin or thick porridge and eaten.
South America: Pozol
At first glance, some people may think I left the 'e' off the word 'pozole', a traditional Mexican stew. However, pozol is an entirely different beast, an ancient food almost totally unknown in the US, but which fueled the Mayan empire and remains a staple food in Southeastern Mexico.
To make pozol, first the corn must be 'nixtamalized': whole kernels are boiled in a large volume of water with calcium hydroxide (10% w/v). This is a processing step in most traditional South American corn recipes, as it allows a person to avoid pellagra (niacin deficiency)! The loosened bran is removed from the kernels by hand.
The kernels are then ground into dough, formed into balls and placed into banana leaves to ferment for one to 14 days. Following fermentation, pozol is diluted in water and consumed raw.
Europe: Sourdough Bread
Sourdough bread is Europe's quintessential fermented grain food. Before purified yeast strains came into widespread use in the 20th century, all bread would have been some form of sourdough.
Although in my opinion wheat is problematic for many people, sourdough fermentation renders it more nutritious and better tolerated by those with gluten/wheat sensitivity. In an interesting series of studies, Dr. Marco Gobbetti's group, among others, has shown that fermentation partially degrades gluten, explaining the ability of fermentation to decrease the adverse effects of gluten in those who are sensitive to it (3). They even showed that people with celiac disease can safely eat wheat bread that has been long-fermented with selected bacteria and yeasts under laboratory conditions (4). Rye contains about half the gluten of bread wheat, and is generally nutritionally superior to wheat, so sourdough rye is a better choice in my opinion.
To make sourdough bread, first the dry grains are ground into flour. Next, the flour is sifted through a screen to remove a portion of the bran. The earliest bread eaters probably didn't do this, although there is evidence of the wealthy eating sifted flour in societies as old as ancient Egypt and ancient Rome. I don't know what the optimum amount of bran to include in flour is, but it's not zero. I would be inclined to keep at least half of it, recognizing that the bran is disproportionately rich in nutrients.
Next, a portion of flour is mixed with water and a "sourdough starter", until it has a runny consistency. The starter is a diverse culture of bacteria and yeast that is carefully maintained by the bread maker. This culture acidifies the batter and produces carbon dioxide gas. The mixture is allowed to ferment for 8-12 hours. Finally, flour and salt are added to the batter and formed into dough balls. These are allowed to ferment and rise for a few hours, then baked.
My Experience
I've tried making ogi (millet) and pozol, and I have to admit that neither attempt was successful. Pozol in particular may depend on local populations of bacteria and yeast, as the grains' microorganisms are killed during processing. However, I do eat fermented grains regularly in the form of homemade brown rice 'uthappam' and sourdough buckwheat 'crepes'. The buckwheat crepes are tasty and easy to make. I'll post a recipe at some point.
The first two recipes are from the FAO publication Fermented Cereals: a Global Perspective (5).
Does Red Wine Protect the Cardiovascular System?
Tuesday, June 08, 2010 11:13 PM
The 'French paradox' rears its ugly head again. The reasoning goes something like this: French people eat more saturated animal fat than any other affluent nation, and have the second-lowest rate of coronary heart disease (only after Japan, which has a much higher stroke rate than France). French people drink red wine. Therefore, red wine must be protecting them against the artery-clogging yogurt, beef and butter.
The latest study to fall into this myth was published in the AJCN recently (1). Investigators showed that 1/3 bottle of red wine per day for 21 days increased blood flow in forearm vessels of healthy volunteers, which they interpreted as "enhanced vascular endothelial function"*. The novel finding in this paper is that red wine consumption increases the migration of certain cells into blood vessels that are thought to maintain and repair the vessels. There were no control groups for comparison, neither abstainers nor a group drinking a different type of alcohol.
The investigators then went on to speculate that the various antioxidant polyphenols in red wine, such as the trendy molecule resveratrol, could be involved. Even though you have to give animals 500 bottles' worth of resveratrol per day to see any effect. But there's another little problem with this hypothesis...
Ethanol-- plain old alcohol. You could drink a 40 oz bottle of malt liquor every night and it would probably do the exact same thing.
No matter what the source, alcohol consumption is associated with a lower risk of cardiovascular disease out to about 3-4 drinks per day, after which the risk goes back up (2, 3)**. The association is not trivial-- up to a 62% lower risk associated with alcohol use. Controlled trials have shown that alcohol, regardless of the source, increases HDL cholesterol and reduces the tendency to clot (4).
Should we all start downing three drinks a day? Not so fast. Although alcohol does probably decrease heart attack risk, the effect on total mortality is equivocal. That's because it increases the risk of cancers and accidents. Alcohol is a drug, and my opinion is that like all drugs, overall it will not benefit the health of a person with an otherwise good diet and lifestyle. That being said, it's enjoyable, so I have no problem with drinking it in moderation. Just don't think you're doing it for your health.
So does red wine decrease the risk of having a heart attack? Yes, just as effectively as malt liquor. It's not the antioxidants and resveratrol, it's the ethanol. The reason the French avoid heart attacks is not because of some fancy compound in their wine that protects them from a high saturated fat intake. It's because they have preserved their diet traditions to a greater degree than most industrialized nations.
I do think it's interesting to speculate about why alcohol (probably) reduces heart attack risk. As far as I know, the mechanism is unknown. Could it be because it relaxes us? I'm going to ponder that over a glass of whiskey...
* It may well represent an improvement of endothelial function, but that's an assumption on the part of the investigators. It belongs in the discussion section, if anywhere, and not in the results section.
** The first study is really interesting. For once, I see no evidence of "healthy user bias". Rates of healthy behaviors were virtually identical across quintiles of alcohol intake. This gives me a much higher degree of confidence in the results.
Sweet Potatoes
Wednesday, May 26, 2010 9:15 AM
We can measure the nutrient and toxin content of a food, and debate the health effects of each of its constituents until we're out of breath. But in the end, we still won't have a very accurate prediction of the health effects of that food. The question we need to answer is this one: has this food sustained healthy traditional cultures?
I'm currently reading a great book edited by Drs. Hugh Trowell and Denis Burkitt, titled Western Diseases: Their Emergence and Prevention. It's a compilation of chapters describing the diet and health of traditional populations around the world as they modernize.
The book contains a chapter on Papua New Guinea highlanders. Here's a description of their diet:
A diet survey was undertaken involving 90 subjects, in which all food consumed by each individual was weighed over a period of seven consecutive days. Sweet potato supplied over 90 percent of their total food intake, while non-tuberous vegetables accounted for less than 5 percent of the food consumed and the intake of meat was negligible... Extensive herds of pigs are maintained and, during exchange ceremonies, large amounts of pork are consumed.
They ate no salt. Their calories were almost entirely supplied by sweet potatoes, with occasional feasts on pork.
How was their health? Like many non-industrial societies, they had a high infant/child mortality rate, such that 43 percent of children died before growing old enough to marry. Surprisingly, protein deficiency was rare. No obvious malnutrition was observed in this population, although iodine-deficiency cretinism occurs in some highlands populations:
Young adults were well built and physically fit and had normal levels of haemoglobin and serum albumin. Further, adult females showed no evidence of malnutrition in spite of the demands by repeated cycles of pregnancy and lactation. On the basis of American standards (Society of Actuaries, 1959), both sexes were close to 100 percent standard weight in their twenties.
The Harvard Pack Test carried out on 152 consecutive subjects demonstrated a high level of physical fitness which was maintained well into middle-age. Use of a bicycle ergometer gave an estimated maximum oxygen uptake of 45.2 ml per kilogram per minute and thus confirmed the high level of cardiopulmonary fitness in this group.
Body weight decreased with age, which is typical of many non-industrial cultures and reflects declining muscle mass but continued leanness.
There was no evidence of coronary heart disease or diabetes. Average blood pressure was on the high side, but did not increase with age. Investigators administered 100 gram glucose tolerance tests and only 3.8 percent of the population had glucose readings above 160 mg/dL, compared to 21 percent of Americans. A study of 7,512 Papuans from several regions with minimal European contact indicated a diabetes prevalence of 0.1 percent, a strikingly low rate. For comparison, in 2007, 10.7 percent of American adults had diabetes (1).
I'm not claiming it's optimal to eat nothing but sweet potatoes. But this is the strongest evidence we're going to come by that sweet potatoes can be eaten in quantity as part of a healthy diet. However, I wish I knew more about the varieties this group ate. Sweet potatoes aren't necessarily sweet. Caribbean 'boniato' sweet potatoes are dry, starchy and off-white. In the US, I prefer the yellow sweet potatoes to the orange variety of sweet potato labeled 'yams', because the former are starchier and less sweet. If I could get my hands on locally grown boniatos here, I'd eat those, but boniatos are decidedly tropical.
Instead, I eat potatoes, but I'm reluctant to recommend them whole-heartedly because I don't know enough about the traditional cultures that consumed them. I believe there are some low-CHD, low-obesity African populations that eat potatoes as part of a starch-based diet, but I haven't looked into it closely enough to make any broad statements. Potatoes have some nutritional advantages over sweet potatoes (higher protein content, better amino acid profile), but also some disadvantages (lower fiber, lower in most micronutrients, toxic glycoalkaloids).
Pastured Dairy may Prevent Heart Attacks
Sunday, May 23, 2010 1:01 AM
Not all dairy is created equal. Dairy from grain-fed and pasture-fed cows differs in a number of ways. Pastured dairy contains more fat-soluble nutrients such as vitamin K2, vitamin A, vitamin E, carotenes and omega-3 fatty acids. It also contains more conjugated linoleic acid, a fat-soluble molecule that has been under intense study due to its ability to inhibit obesity and cancer in animals. The findings in human supplementation trials have been mixed, some confirming the animal studies and others not. In feeding experiments in cows, Dr. T. R. Dhiman and colleagues found the following (1):
Cows grazing pasture and receiving no supplemental feed had 500% more conjugated linoleic acid in milk fat than cows fed typical dairy diets.
Fat from ruminants such as cows, sheep and goats is the main source of CLA in the human diet. CLA is fat-soluble. Therefore, skim milk doesn't contain any. It's also present in human body fat in proportion to dietary intake. This can come from dairy or flesh.
In a recent article from the AJCN, Dr. Liesbeth Smit and colleagues examined the level of CLA in the body fat of Costa Rican adults who had suffered a heart attack, and compared it to another group who had not (a case-control study, for the aficionados). People with the highest level of CLA in their body fat were 49% less likely to have had a heart attack, compared to those with the lowest level (2).
Since dairy was the main source of CLA in this population, the association between CLA and heart attack risk is inextricable from the other components in pastured dairy fat. In other words, CLA is simply a marker of pastured dairy fat intake in this population, and the (possible) benefit could just as easily have come from vitamin K2 or something else in the fat.
This study isn't the first one to suggest that pastured dairy fat may be uniquely protective. The Rotterdam and EPIC studies found that a higher vitamin K2 intake is associated with a lower risk of heart attack, cancer and overall mortality (3, 4, 5). In the 1940s, Dr. Weston Price estimated that pastured dairy contains up to 50 times more vitamin K2 than grain-fed dairy. He summarized his findings in the classic book Nutrition and Physical Degeneration. This finding has not been repeated in recent times, but I have a little hunch that may change soon...
Vitamin K2
Cardiovascular Disease and Vitamin K2
Can Vitamin K2 Reverse Arterial Calcification?
Malocclusion Posts Translated into German
Friday, May 21, 2010 12:19 PM
It's nice to see on my website statistics program that Whole Health Source has a solid international following. As commonly as English is spoken throughout the world however, there are many people who do not have access to this blog due to a language barrier.
A gentleman by the name of Bertram has translated/summarized my series on the causes and prevention of malocclusion (misaligned teeth) into German. His site is OriginalHealth.net, and you can find the first post here, with links to the subsequent 8. It looks like an interesting site-- I wish I could read German. Thanks Bertram!
Intervew with Chris Kresser of The Healthy Skeptic
Wednesday, May 19, 2010 12:43 PM
Last week, I did an audio interview with Chris Kresser of The Healthy Skeptic, on the topic of obesity. We put some preparation into it, and I think it's my best interview yet. Chris was a gracious host. We covered some interesting ground, including (list copied from Chris's post):
* The little known causes of the obesity epidemic
* Why the common weight loss advice to “eat less and exercise more” isn’t effective
* The long-term results of various weight loss diets (low-carb, low-fat, etc.)
* The body-fat setpoint and its relevance to weight regulation
* The importance of gut flora in weight regulation
* The role of industrial seed oils in the obesity epidemic
* Obesity as immunological and inflammatory disease
* Strategies for preventing weight gain and promoting weight loss
Some of the information we discussed is not yet available on my blog. You can listen to the interview through Chris's post here.
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