The Kitavans: Wisdom from the Pacific Islands

There are very few cultures left on this planet that have not been affected by modern food habits. There are even fewer that have been studied thoroughly. The island of Kitava in Papua New Guinea is host to one such culture, and its inhabitants have many profound things to teach us about diet and health.

The Kitava study, a series of papers produced primarily by Dr. Staffan Lindeberg and his collaborators, offers a glimpse into the nutrition and health of an ancient society, using modern scientific methods. This study is one of the most complete and useful characterizations of the diet and health of a non-industrial society I have come across. It's also the study that created, and ultimately resolved, my cognitive dissonance over the health effects of carbohydrate.

From the photos I've seen, the Kitavans are beautiful people. They have the broad, attractive faces, smooth skin and excellent teeth typical of healthy non-industrial peoples.

Like the Kuna, Kitavans straddle the line between agricultural and hunter-gatherer lifestyles. They eat a diet primarily composed of tubers (yam, sweet potato, taro and cassava), fruit, vegetables, coconut and fish, in order of calories. This is typical of traditional Pacific island cultures, although the relative amounts differ.

Grains, refined sugar, vegetable oils and other processed foods are virtually nonexistent on Kitava. They get an estimated 69% of their calories from carbohydrate, 21% from fat, 17% from saturated fat and 10% from protein. Most of their fat intake is saturated because it comes from coconuts. They have an omega-6 : omega-3 ratio of approximately 1:2. Average caloric intake is 2,200 calories per day (9,200 kJ). By Western standards, their diet is high in carbohydrate, high in saturated fat, low in total fat, a bit low in protein and high in calories.

Now for a few relevant facts before we really start diving in:

• Kitavans are moderately active. They have an activity level comparable to a moderately active Swede, the population to which Dr. Lindeberg draws frequent comparisons.
  


• They have abundant food, and shortage is uncommon.
  


• Their good health is probably not related to genetics, since genetically similar groups in the same region are exquisitely sensitive to the ravages of industrial food. Furthermore, the only Kitavan who moved away from the island to live a modern life is also the only fat Kitavan.
  


• Their life expectancy at birth is estimated at 45 years (includes infant mortality), and life expectancy at age 50 is an additional 25 years. This is remarkable for a culture with limited access to modern medicine.
  


• Over 75% of Kitavans smoke cigarettes, although in small amounts. Even the most isolated societies have their modern vices.

The first study in the series is provocatively titled "Apparent absence of stroke and ischaemic heart disease in a traditional Melanesian island: a clinical study in Kitava." In it, Dr. Lindeberg presents data from interviews and electrocardiograms (ECG) suggesting that heart disease and stroke are absent or extremely rare on Kitava. The inhabitants are entirely unfamiliar with the (characteristic) symptoms of heart attack and stroke, despite the sizable elderly population. This is confirmed by the ECG findings, which indicate remarkable cardiovascular health. It also agrees with data from other traditional cultures in Papua New Guinea. Lindeberg states:

For the whole of PNG, no case of IHD or atherothrombotic stroke has been reported in clinical investigations and autopsy studies among traditionally living Melanesians for more than seven decades, though an increasing number of myocardial infarctions [heart attacks] and angina pectoris in urbanized populations have been reported since the 1960s.

Dementia was not found except in in two young Kitavans, who were born handicapped. The elderly remained sharp until death, including one man who reached 100 years of age. Kitavans are also unfamiliar with external cancers, with the exception of one possible case of breast cancer in an elderly woman.

Overall, Kitavans possess a resistance to degenerative diseases that is baffling to industrialized societies. Not only is this typical of non-industrial cultures, I believe it represents the natural state of existence for Homo sapiens. Like all other animals, humans are healthy and robust when occupying their preferred ecological niche. Our niche happens to be a particularly broad one, ranging from near-complete carnivory to plant-rich omnivory. But it does not include large amounts of industrial foods.

In the next few posts, I'll discuss more specific data about the health of the Kitavans.

Rats on Junk Food

If diet composition causes hyperphagia, we should be able to see it in animals. I just came across a great study from the lab of Dr. Neil Stickland that explored this in rats. They took two groups of pregnant rats and fed them two different diets ad libitum, meaning the rats could eat as much as they wanted. Here's what the diets looked like:

The animals were fed two types of diet throughout the study. They were fed either RM3 rodent chow alone ad libitum (SDS Ltd, Betchworth, Surrey, UK) or with a junk food diet, also known as cafeteria diet, which consisted of eight different types of palatable foods, purchased from a British supermarket. The palatable food included biscuits, marshmallows, cheese, jam doughnuts, chocolate chip muffins, butter flapjacks, potato crisps and caramel/chocolate bars.

It's important to note that the junk food-fed rats had access to rat chow as well. Now here's where it gets interesting. Rats with access to junk food in addition to rat chow ate 56% more calories than the chow-only group! Here's what they had to say about it:

These results clearly show that pregnant rats, given ad libitum access to junk food, exhibited hyperphagia characterised by a marked preference for foods rich in fat, sucrose and salt at the expense of protein-rich foods, when compared with rats that only had access to rodent chow. Although the body mass of dams was comparable among all groups at the start of the experiment, the increased energy intake in the junk food group throughout gestation was accompanied by an increase in body mass at G20 [gestational day 20] with the junk food-fed dams being 13 % heavier than those fed chow alone.

Hmm, this is remarkably reminiscent of what's happening to a certain group of humans in North America right now: give them access to food made mostly of refined grains, sugar, and industrially processed vegetable oil. They will prefer it to healthier food, to the point of overeating. The junk food then drives hyperphagia by interfering with the body's feedback loops that normally keep feeding behaviors and body fat within the optimal range. These data support the hypothesis that metabolic damage is the cause of, not the result of, "super-sized" food portions and other similar cultural phenomena.

The rest of the paper is interesting as well. Pups born to mothers who ate junk food while pregnant and lactating had a greater tendency to eat junk than pups born to mothers who ate rat chow during the same period. This underscores the idea that poor nutrition can set a child up for a lifetime of problems.

Hyperphagia

One of the things I didn't mention in the last post is that Americans are eating more calories than ever before. According to Centers for Disease Control NHANES data, in 2000, men ate about 160 more calories per day, and women ate about 340 more than in 1971. That's a change of 7% and 22%, respectively. The extra calories come almost exclusively from refined grains, with the largest single contribution coming from white wheat flour (correction: the largest single contribution comes from corn sweeteners, followed by white wheat flour).

Some people will see those data and decide the increase in calories is the explanation for the expanding American waistline. I don't think that's incorrect, but I do think it misses the point. The relevant question is "why are we eating more calories now than we were in 1971?"

We weren't exactly starving in 1971. And average energy expenditure, if anything, has actually increased. So why are we eating more? I believe that our increased food intake, or hyperphagia, is the result of metabolic disturbances, rather than the cause of them.

Humans, like all animals, have a sophisticated system of hormones and brain regions whose function is to maintain a proper energy balance. Part of the system's job is to keep fat mass at an appropriate level. With a properly functioning system, feedback loops inhibit hunger once fat mass has reached a certain level, and also increase resting metabolic rate to burn excess calories. If the system is working properly, it's very difficult to gain weight. There have been a number of overfeeding studies in which subjects have consumed huge amounts of excess calories. Some people gain weight, many don't.

The fact that fat mass is hormonally regulated can be easily seen in other mammals. When was the last time you saw a fat squirrel in the springtime? When was the last time you saw a thin squirrel in the fall? These events are regulated by hormones. A squirrel in captivity will put on weight in the fall, even if its daily food intake is not changed.

A key hormone in this process is leptin. Leptin levels are proportional to fat mass, and serve to inhibit hunger and eating behaviors. Under normal conditions, the more fat tissue a person has, the more leptin they will produce, and the less they will eat until the fat mass has reached the body's preferred 'set-point'. The problem is that overweight Westerners are almost invariably leptin-resistant, meaning their body doesn't respond to the signal to stop eating!

Leptin resistance leads to hyperphagia, overweight and the metabolic syndrome (a common cluster of symptoms that implies profound metabolic disturbance). It typically precedes insulin resistance during the downward slide towards metabolic syndrome.

I suspect that wheat, sugar and perhaps other processed foods cause hyperphagia. I believe hyperphagia is at least partially secondary to a disturbed metabolism. There's something about industrial foods that reached a critical mass in the mid-70s. The shift in diet sent us into a tailspin of excessive eating and unprecedented weight gain.

Media Misinterpretations

The New York Times just published an article called "The Overflowing American Dinner Plate", in which they describe changes in the American diet since 1970, the period during which the obesity rate doubled. Bill Marsh used USDA estimates of food consumption from 1970 to 2006. Predictably, he focuses on fat consumption, and writes that it has increased by 59% in the same time period.

The problem is, we aren't eating any more fat than we were in 1970. The US Centers for Disease Control NHANES surveys show that total fat consumption has remained the same since 1971, and has decreased as a percentage of calories. I've been playing around with the USDA data for months now, and I can tell you that Marsh misinterpreted it in a bad way. Here are the raw data, for anyone who's interested. They're in easy-to-use Excel spreadsheets. I highly recommend poking around them if you're interested.

The reason Marsh was confused by the USDA data is that he confused "added fats" with "total fat".  While total fat intake has remained stable over this time period, added fats have increased by 59%. The increase is almost exclusively due to industrially processed seed oils (butter and lard have decreased). Total fat has remained the same because we now eat low-fat cuts of meat and low-fat dairy products to make up for it!

Another problem with the article is it only shows percent changes in consumption of different foods, rather than absolute amounts. This obscures some really meaningful information. For example, grain consumption is up a whopping 42%. That is the largest single food group change if you exclude the misinterpreted fat data. Corn is up 188%, rice 170%, wheat 21%. But in absolute amounts, the increase in wheat consumption is larger than corn or rice! That's because baseline wheat consumption dwarfed corn and rice. We don't get that information from the data presented in the article, due to the format.

So now that I've deconstructed the data, let's see what the three biggest changes in the American diet from 1970 to 2006 actually are:

• We're eating more grains, especially white wheat flour
  


• We're eating more added sweeteners, especially high-fructose corn syrup


• Animal fats from milk and meat have been replaced by processed seed oils
  

Wheat + sugar + processed vegetable oil = fat and unhealthy. Sounds familiar, doesn't it?

Composition of the Hunter-Gatherer Diet

I bumped into a fascinating paper today by Dr. Loren Cordain titled "Plant-Animal Subsistence Ratios and Macronutrient Estimations in Worldwide Hunter-Gatherer Diets." Published in 2000 in the American Journal of Clinical Nutrition, the paper estimates the food sources and macronutrient intakes of historical hunter-gatherers based on data from 229 different groups. Based on the available data, these groups did not suffer from the diseases of civilization. This is typical of hunter-gatherers.

Initial data came from the massive Ethnographic Atlas by Dr. George P. Murdock, and was analyzed further by Cordain and his collaborators. Cordain is a professor at Colorado State University, and a longtime proponent of paleolithic diets for health. He has written extensively about the detrimental effects of grains and other modern foods. Here's his website.

The researchers broke food down into three categories: hunted animal foods, fished animal foods and gathered foods. "Gathered foods" are primarily plants, but include some animal foods as well:

Although in the present analysis we assumed that gathering would only include plant foods, Murdock indicated that gathering activities could also include the collection of small land fauna (insects, invertebrates, small mammals, amphibians, and reptiles); therefore, the compiled data may overestimate the relative contribution of gathered plant foods in the average hunter-gatherer diet.

There are a number of striking things about the data once you sum them up. First of all, diet composition varied widely. Many groups were almost totally carnivorous, with 46 getting over 85% of their calories from hunted foods. However, not a single group out of 229 was vegetarian or vegan. No group got less than 15% of their calories from hunted foods, and only 2 of 229 groups ate 76-85% of their calories from gathered foods (don't forget, "gathered foods" also includes small animals). On average, the hunter-gatherer groups analyzed got about 70% of their calories from hunted foods. This makes the case that meat-heavy omnivory is our preferred ecological niche. However, it also shows that we can thrive on a plant-rich diet containing modest amounts of quality animal foods.

The paper also discusses the nature of the plant foods hunter-gatherers ate. Although they ate a wide variety of plants occasionally, more typically they relied on a small number of staple foods with a high energy density. There's a table in the paper that lists the most commonly eaten plant foods. "Vegetables" are notably underrepresented. The most commonly eaten plant foods are fruit, underground storage organs (tubers, roots, corms, bulbs), nuts and other seeds. Leaves and other low-calorie plant parts were used much less frequently.

The paper also gets into the macronutrient composition of hunter-gatherer diets.  He writes that

...the most plausible... percentages of total energy from the macronutrients would be 19-35% for protein, 22-40% for carbohydrate, and 28-58% for fat.

He derives these numbers from projections based on the average composition of plant foods, and the whole-body composition of representative animal foods (includes organs, marrow, blood etc., which they typically ate). 

However, some groups may have eaten more fat than this.  Natives on the North American Pacific coast rendered fat from fish, seals, bears and whales, using it liberally in their food. Here's an excerpt from The Northwest Coast by James Swan, who spent three years living among the natives of the Washington coast in the 1850s:

About a month after my return from the treaty, a whale was washed ashore on the beach between Toke's Point and Gray's Harbor and all the Indians about the Bay went to get their share... The Indians were camped near by out of the reach of the tide, and were all very busy on my arrival securing the blubber either to carry home to their lodges or boiling it out on the spot, provided they happened to have bladders or barrels to put the oil in. Those who were trying out [rendering] the blubber cut it into strips about two inches wide, one and a half inches thick, and a foot long. These strips were then thrown into a kettle of boiling water, and as the grease tried out it was skimmed off with clam shells and thrown into a tub to cool and settle. It was then carefully skimmed off again and put into the barrels or bladders for use. After the strips of blubber have been boiled, they are hung up in the smoke to dry and are then eaten. I have tried this sort of food but must confess that, like crow meat, "I didn't hanker arter it".

I was very impressed by the paper overall. I think it presents a good, simple model for eating well: eat whole foods that are similar to those that hunter-gatherers would have eaten, including at least 20% of calories from high-quality animal sources. Organs are mandatory, vegetables may not be. Sorry, Grandma.

The Inuit: Lessons from the Arctic

The Inuit (also called Eskimo) are a group of hunter-gatherer cultures who inhabit the arctic regions of Alaska, Canada and Greenland. They are a true testament to the toughness, adaptability and ingenuity of the human species. Their unique lifestyle has a lot of information to offer us about the boundaries of the human ecological niche. Weston Price was fascinated by their excellent teeth, good nature and overall robust health. Here's an excerpt from Nutrition and Physical Degeneration:

"In his primitive state he has provided an example of physical excellence and dental perfection such as has seldom been excelled by any race in the past or present...we are also deeply concerned to know the formula of his nutrition in order that we may learn from it the secrets that will not only aid in the unfortunate modern or so-called civilized races, but will also, if possible, provide means for assisting in their preservation."

The Inuit are cold-hardy hunters whose traditional diet consists of a variety of sea mammals, fish, land mammals and birds. They invented some very sophisticated tools, including the kayak, whose basic design has remained essentially unchanged to this day. Most groups ate virtually no plant food. Their calories came primarily from fat, up to 75%, with almost no calories coming from carbohydrate. Children were breast-fed for about three years, and had solid food in their diet almost from birth. As with most hunter-gatherer groups, they were free from chronic disease while living a traditional lifestyle, even in old age. Here's a quote from Observations on the Western Eskimo and the Country they Inhabit; from Notes taken During two Years [1852-54] at Point Barrow, by Dr. John Simpson:

These people [the Inuit] are robust, muscular and active, inclining rather to spareness [leanness] than corpulence [overweight], presenting a markedly healthy appearance. The expression of the countenance is one of habitual good humor. The physical constitution of both sexes is strong. Extreme longevity is probably not unknown among them; but as they take no heed to number the years as they pass they can form no guess of their own ages.

One of the common counterpoints I hear to the idea that high-fat hunter-gatherer diets are healthy, is that exercise protects them from the ravages of fat. The Inuit can help us get to the bottom of this debate. Here's a quote from Cancer, Disease of Civilization (1960, Vilhjalmur Stefansson):

"They are large eaters, some of them, especially the women, eating all the time..." ...during the winter the Barrow women stirred around very little, did little heavy work, and yet "inclined more to be sparse than corpulent" [quotes are the anthropologist Dr. John Murdoch, reproduced by Stefansson].

Another argument I sometimes hear is that the Inuit are genetically adapted to their high-fat diet, and the same food would kill a European. This appears not to be the case. The anthropologist and arctic explorer Vilhjalmur Stefansson spent several years living with the Inuit in the early 20th century. He and his fellow Europeans and Americans thrived on the Inuit diet. American doctors were so incredulous that they defied him and a fellow explorer to live on a diet of fatty meat only for one year, under the supervision of the American Medical Association. To the doctors' dismay, they remained healthy, showing no signs of scurvy or any other deficiency (JAMA 1929;93:20–2).

Yet another amazing thing about the Inuit was their social structure. Here's Dr. John Murdoch again (quoted from Cancer, Disease of Civilization):

The women appear to stand on a footing of perfect equality with the men, both in the family and the community. The wife is the constant and trusted companion of the man in everything except the hunt, and her opinion is sought in every bargain or other important undertaking... The affection of parents for their children is extreme, and the children seem to be thoroughly worthy of it. They show hardly a trace of fretfulness or petulance so common among civilized children, and though indulged to an extreme extent are remarkably obedient. Corporal punishment appears to be absolutely unknown, and children are rarely chided or punished in any way.

Unfortunately, those days are long gone. Since adopting a modern processed-food diet, the health and social structure of the Inuit has deteriorated dramatically. This had already happened to most groups by Weston Price's time, and is virtually complete today. Here's Price:

In the various groups in the lower Kuskokwim seventy-two individuals who were living exclusively on native foods had in their 2,138 teeth only two teeth or 0.09 per cent that had ever been attacked by tooth decay. In this district eighty-one individuals were studied who had been living in part or in considerable part on modern foods, and of their 2, 254 teeth 394 or 13 per cent had been attacked by dental caries. This represents an increase in dental caries of 144 fold.... When these adult Eskimos exchange their foods for our modern foods..., they often have very extensive tooth decay and suffer severely.... Their plight often becomes tragic since there are no dentists in these districts.

Modern Inuit also suffer from very high rates of diabetes and overweight. This has been linked to changes in diet, particularly the use of white flour, sugar and processed oils.

Overall, the unique lifestyle and diet of the Inuit have a lot to teach us. First, that some humans are capable of being healthy eating mostly animal foods. Second, that some humans are able to thrive on a high-fat diet. Third, that humans are capable of living well in extremely harsh and diverse environments. Fourth, that the shift from natural foods to processed foods, rather than changes in macronutrient composition, is the true cause of the diseases of civilization.

Book Review: "The Human Diet: Its Origins and Evolution"

I recently read this book after discovering it on another health site. It's a compilation of chapters written by several researchers in the fields of comparative biology, paleontology, archaeology and zoology. It's sometimes used as a textbook.

I've learned some interesting things, but overall it was pretty disappointing. The format is disjointed, with no logical flow between chapters. I also would not call it comprehensive, which is one of the things I look for in a textbook. Here are some of the interesting points:

• Humans in industrial societies are the only mammals to commonly develop hypertension, and are the only free-living primates to become overweight.
  
• The adoption of grains as a primary source of calories correlated with a major decrease in stature, decrease in oral health, decrease in bone density, and other problems. This is true for wheat, rice, corn and other grains.
• Cranial capacity has also declined 11% since the late paleolithic, correlating with a decrease in the consumption of animal foods and an increase in grains.
• According to carbon isotope ratios of teeth, corn did not play a major role in the diet of native Americans until 800 AD. Over 15% of the teeth of post-corn South American cultures showed tooth decay, compared with less than 5% for pre-corn cultures (many of which were already agricultural, just not eating corn).
  
• Childhood mortality seems to be similar among hunter-gatherers and non-industrial agriculturists and pastoralists.
  
• Women may have played a key role in food procurement through foraging. This is illustrated by a group of modern hunter-gatherers called the Hadza. While men most often hunt, which supplies important nutrients intermittently, women provide a steady stream of calories by foraging for tubers.
• We have probably been eating starchy tubers for between 1.5 and 2 million years, which precedes our species. Around that time, digging tools, (controversial) evidence of controlled fire and changes in digestive anatomy all point to use of tubers and cooked food in general. Tubers make sense because they are a source of calories that is much more easily exploited than wild grains in most places.
• Our trajectory as a species has been to consume a diet with more calories per unit fiber. As compared to chimps, who eat leaves and fruit all day and thus eat a lot of fiber to get enough calories, our species and its recent ancestors ate a diet much lower in fiber.
  
• Homo sapiens has always eaten meat.
  

The downside is that some chapters have a distinct low-fat slant. One chapter attempted to determine the optimal diet for humans by comparing ours to the diets of wild chimps and other primates. Of course, we eat more fat than a chimp, but I don't think that gets us anywhere. Especially since one of our closest relatives, the neanderthal, was practically a carnivore.
They consider the diet composition of modern hunter-gatherers that eat low-fat diets, but don't include data on others with high-fat diets like the Inuit.

There's some good information in the book, if you're willing to dig through a lot of esoteric data on the isotope ratios of extinct hominids and that sort of thing.

Grains and Human Evolution

[Update 8/2011: as I've learned more about human genetics and evolution, I've come to appreciate that many Europeans actually descend from early adopters of agriculture more than they descend from the hunter-gatherers that previously occupied Europe.  Also, 10,000 years has been long enough for significant genetic adaptation.  Read The 10,000 Year Explosion for more information].

You've heard me say that I believe grains aren't an ideal food for humans. Part of the reason rests on the assertion that we have not been eating grains for long enough to have adapted to them. In this post, I'll go over what I know about the human diet before and after agriculture, and the timeline of our shift to a grain-based diet. I'm not an archaeologist so I won't claim that all these numbers are exact, but I think they are close enough to make my point.

As hunter-gatherers, we ate some combination of the following: land mammals (including organs, fat and marrow), cooked tubers, seafood (fish, mammals, shellfish, seaweed), eggs, nuts, fruit, honey, "vegetables" (stems, leaves, etc.), mushrooms, assorted land animals, birds and insects. The proportion of each food varied widely between groups and even seasons. This is pretty much what we've been living on since we evolved as a species, and even before, for a total of 1.5 million years or so (this number is controversial but is supported by multiple lines of evidence). There are minor exceptions, including the use of wild grains in a few areas, but for the most part, that's it.

The first evidence of a calorically important domesticated crop I'm aware of was about 11,500 years ago in the fertile crescent. They were cultivating an early ancestor of wheat called emmer. Other grains popped up independently in what is now China (rice; ~10,000 years ago), and central America (corn; ~9,000 years ago). That's why people say humans have been eating grains for about 10,000 years.

The story is more complicated than the dates suggest, however. Although wheat had its origin 11,500 years ago, it didn't become widespread in Western Europe for another 4,500 years. So if you're of European descent, your ancestors have been eating grains for roughly 7,000 years. Corn was domesticated 9,000 years ago, but according to the carbon ratios of human teeth, it didn't become a major source of calories until about 1,200 years ago! Many American groups did not adopt a grain-based diet until 100-300 years ago, and in a few cases they still have not. If you are of African descent, your ancestors have been eating grains for 9,000 to 0 years, depending on your heritage. The change to grains was accompanied by a marked decrease in dental health that shows up clearly in the archaeological record.

Practically every plant food contains some kind of toxin, but grains produce a number of nasty ones that humans are not well adapted to. Grains contain a large amount of phytic acid for example, which strongly inhibits the absorption of a number of important minerals. Tubers, which were our main carbohydrate source for about 1.5 million years before agriculture, contain less of it. This may have been a major reason why stature decreased when humans adopted grain-based agriculture. There are a number of toxins that occur in grains but not in tubers, such as certain heat-resistant lectins.

Non-industrial cultures often treated their seeds, including grains, differently than we do today. They used soaking, sprouting and long fermentation to decrease the amount of toxins found in grains, making them more nutritious and digestible. Most grain staples are not treated in this way today, and so we bear the brunt of their toxins even more than our ancestors did.

From an evolutionary standpoint, even 11,500 years is the blink of an eye. Add to that the fact that many people descend from groups that have been eating grains for far less time than that, and you begin to see the problem. There is no doubt that we have begun adapting genetically to grains. All you have to do to understand this is look back at the archaeological record, to see the severe selective pressure (read: disease) that grains placed on its early adopters. But the question is, have we had time to adapt sufficiently to make it a healthy food? I would argue the answer is no.

There are a few genetic adaptations I'm aware of that might pertain to grains: the duplication of the salivary amylase gene, and polymorphisms in the angiotensin-converting enzyme (ACE) and apolipoprotein B genes. Some groups duplicated a gene that secretes the enzyme amylase into the saliva, increasing its production. Amylase breaks down starch, indicating a possible increase in its consumption. The problem is that we were getting starch from tubers before we got it from grains, so it doesn't really argue for either side in my opinion. The ACE and apolipoprotein B genes may be more pertinent, because they relate to blood pressure and LDL cholesterol. Blood pressure and blood cholesterol are both factors that respond well to low-carbohydrate (and thus low-grain) diets, suggesting that the polymorphisms may be a protective adaptation against the cardiovascular effects of grains.

The fact that up to 1% of people of European descent may have full-blown celiac disease attests to the fact that 7,000 years have not been enough time to fully adapt to wheat on a population level. Add to that the fact that nearly half of genetic Europeans carry genes that are associated with celiac, and you can see that we haven't been weeded out thoroughly enough to tolerate wheat, the oldest grain!

Based on my reading, discussions and observations, I believe that rice is the least problematic grain, wheat is the worst, and everything else is somewhere in between. If you want to eat grains, it's best to soak, sprout or ferment them. This activates enzymes that break down most of the toxins. You can soak rice, barley and other grains overnight before cooking them. Sourdough bread is better than normal white bread. Unfermented, unsprouted whole wheat bread may actually be the worst of all. 

Another China Tidbit

A final note about the Chinese study in the previous post: the overweight vegetable-eaters (read: wheat eaters) exercised more than their non-vegetable-eating, thin neighbors. So although their average calorie intake was a bit higher, their expenditure was as well. 

Although I speculated in the last post that affluent people might be eating more wheat and fresh vegetables, the data don't support that. Participants with the highest income level actually adhered to the wheat and vegetable-rich pattern the least, while low-income participants were most likely to eat this way.

Interestingly, education showed a (weaker) trend in the opposite direction. More educated participants were more likely to eat the wheat-vegetable pattern, while the opposite was true of less educated participants. Thus, it looks like wheat makes people more educated. Just kidding, that's exactly the logic we have to avoid when interpreting this type of study!

Wheat in China

Dr. Michael Eades linked to an interesting study yesterday on his Health and Nutrition blog. It's entitled "Vegetable-Rich Food Pattern is Related to Obesity in China."

It's one of these epidemiological studies where they try to divide subjects into different categories of eating patterns and see how health problems associate with each one. They identified four patterns: the 'macho' diet high in meat and alcohol; the 'traditional' diet high in rice and vegetables; the 'sweet tooth' pattern high in cake, dairy and various drinks; and the 'vegetable rich' diet high in wheat, vegetables, fruit and tofu. The only pattern that associated with obesity was the vegetable-rich diet. The 25% of people eating closest to the vegetable-rich pattern were more than twice as likely to be obese as the 25% adhering the least.

The authors of the paper try to blame the increased obesity on a higher intake of vegetable oil from stir-frying the vegetables, but that explanation is misleading. A cursory glance at table 3 reveals that the vegetable-eaters weren't eating any more fat than their thinner neighbors. Dr. Eades suggests that their higher carbohydrate intake (+10%) was partially responsible for the weight gain, but I wasn't satisfied with that explanation so I took a closer look.  Dr. Eades also pointed to their higher calorie intake (+120 kcal/day), which makes sense to me.

One of the most striking elements of the 'vegetable-rich' food pattern is its replacement of rice with wheat flour. The 25% of the study population that adhered the least to the vegetable-rich food pattern ate 7.3 times more rice than wheat, whereas the 25% sticking most closely to the vegetable-rich pattern ate 1.2 times more wheat than rice! In other words, wheat flour rather than rice was their single largest source of calories. This association was much stronger than the increase in vegetable consumption itself!

All of a sudden, the data make more sense. Wheat seems to associate with health problems in many contexts. Perhaps the reason we don't see the same type of association in American epidemiological studies is that everyone eats wheat. Only in a culture that has a true diversity of diet can you find a robust association like this. The replacement of rice with wheat may have caused the increase in calorie intake as well. Clinical trials of low-carbohydrate diets as well as 'paleolithic diets' have shown good metabolic outcomes from wheat avoidance, although one can't be sure what role wheat plays from those data.

I don't think the vegetables had anything to do with the weight gain, they were just incidentally associated with wheat consumption. But I do think these data are difficult to reconcile with the idea that vegetables protect against overweight.

Celiac and Fat-Soluble Vitamins

One of the things I've been thinking about lately is the possibility that intestinal damage due to gluten grains (primarily wheat) contributes to the diseases of civilization by inhibiting the absorption of fat-soluble vitamins. If it were a contributing factor, we would expect to see a higher incidence of the common chronic diseases in newly-diagnosed celiac patients, who are often deficient in fat-soluble vitamins. We might also see a resolution of chronic disease in celiac patients who have been adhering faithfully to a long-term, gluten-free diet.

One thing that definitely associates with celiac disease is bone and tooth problems. Celiac patients often present with osteoporosis, osteopenia (thin bones), cavities or tooth enamel abnormalities (thanks Peter).

An Italian study showed that among 642 heart transplant candidates, 1.9% had anti-endomyosal antibodies (a feature of celiac), compared with 0.35% of controls. That's more than a 5-fold enrichment! The majority of those patients were presumably unaware of their celiac disease, so they were not eating a gluten-free diet.

Interestingly, celiac doesn't seem to cause obesity; to the contrary. That's one facet of modern health problems that it definitely does not cause.

The relationship between cancer and celiac disease is very interesting. The largest study I came across was conducted in Sweden using retrospective data from 12,000 celiac patients. They found that adult celiac patients have a higher overall risk of cancer, but that the extra risk disappears with age. The drop in cancer incidence may reflect dropping gluten following a celiac diagnosis. Here's another study showing that the elevated cancer risk occurs mostly in the first year after diagnosis, suggesting that eliminating gluten solves the problem. Interestingly, celiac patients have a greatly elevated risk of lymphoma, but a lower risk of breast cancer.

There's a very strong link between celiac and type I diabetes. In a large study, 1 in 8 type I diabetic children had celiac disease. This doesn't necessarily tell us much since celiac and type I diabetes are both autoimmune disorders.

One last study to add a nail to the coffin. Up to this point, all the studies I've mentioned have been purely observational, not able to establish a causal relationship. I came across a small study recently which examined the effect of a high-fiber diet on vitamin D metabolism in healthy (presumably non-celiac) adults. They broke the cohort up into two groups, and fed one group 20g of bran in addition to their normal diet. The other group got nothing extra. The bran-fed group had a vitamin D elimination half-life of 19.5 days, compared to 27.5 for the control group. In other words, for whatever reason, the group eating extra bran was burning through their vitamin D reserves 30% faster than the control group.

Unfortunately, the paper doesn't say what kind of bran it was, but it was probably wheat or oat (**Update- it's wheat bran**). This is important because it would determine if gluten was involved. Either way, it shows that something in grains can interfere with fat-soluble vitamin status, which is consistent with the staggering negative effect of refined wheat products on healthy non-industrialized cultures.

Add to this the possibility that many people may have some degree of gluten sensitivity, and you start to see a big problem. All together, the data are consistent with gluten grains interfering with fat-soluble vitamin status in a subset of people. As I discussed earlier, this could contribute to the diseases of civilization. These data don't prove anything conclusively, but I do find them thought-provoking.

Thanks to Dudua for the CC photo

Vitamin K2, menatetrenone (MK-4)

Weston Price established the importance of the MK-4 isoform of vitamin K2 (hereafter, K2) with a series of interesting experiments. He showed in chickens that blood levels of calcium and phosphorus depended both on vitamin A and K2, and that the two had synergistic effects on mineral absorption. He also showed that chickens preferred eating butter that was rich in K2 over butter low in K2, even when the investigators couldn't distinguish between them. Young turkeys fed K2-containing butter oil along with cod liver oil (A and D) also grew at a much faster rate than turkeys fed cod liver oil alone.

He hypothesized that vitamin A, vitamin D and vitamin K2 were synergistic and essential for proper growth and subsequent health. He particularly felt that the combination was important for proper mineral absorption and metabolism. He used a combination of high-vitamin cod liver oil and high-vitamin butter oil to heal cavities, reduce oral bacteria counts, and cure numerous other afflictions in his patients. He also showed that the healthy non-industrial groups he studied had a much higher intake of these fat-soluble, animal-derived vitamins than more modern cultures.

Price found an inverse correlation between the levels of K2 in butter and mortality from cardiovascular disease and pneumonia in a number of different regions. A recent study examined the relationship between K2 (MK-4 through 10) consumption and heart attack risk in 4,600 Dutch men. They found a strong inverse association between K2 consumption and heart attack mortality risk. Men with the highest K2 consumption had a whopping 51% lower risk of heart attack mortality and a 26% lower risk of death from all causes compared to men eating the least K2! Their sources of K2 MK-4 were eggs, meats and dairy. They obtained MK-5 through MK-10 from fermented foods and fish. The investigators found no association with K1, the form found in plants.

Perigord, France is the world's capital of foie gras, or fatty goose liver. Good news for the bon vivants: foie gras turns out to be the richest known source of K2. Perigord also has the lowest rate of cardiovascular mortality in France, a country already noted for its low CVD mortality.

Rats fed warfarin, a drug that inhibits K2 recycling, develop arterial calcification. Feeding the rats K2 completely inhibits this effect. Mice lacking matrix Gla protein (MGP), a vitamin K-dependent protein that guards against arterial calcification, develop heavily calcified aortas and die prematurely. So the link between K2 and cardiovascular disease is a very strong one.

Mammals can synthesize K2 MK-4 from K1 to some degree, so dietary K1 and other forms of vitamin K may contribute to K2 MK-4 status. 

The synergism Weston Price observed between vitamins A, D and K2 now has a solid mechanism. In a nutshell, vitamins A and D signal the production of some very important proteins, and K2 is required to activate them once they are made. Many of these proteins are involved in mineral metabolism, thus the effects Price saw in his experiments and observations in non-industrialized cultures. For example, osteocalcin is a protein that organizes calcium and phosphorus deposition in the bones and teeth. It's produced by cells in response to vitamins A and D, but requires K2 to perform its function. This suggests that the effects of vitamin D on bone health could be amplified greatly if it were administered along with K2. By itself, K2 is already highly protective against fractures in the elderly. It works out perfectly, since K2 also protects against vitamin D toxicity.

I'm not going to go through all the other data on K2 in detail, but suffice it to say it's very very important. I believe that K2 is a 'missing link' that explains many of our modern ills, just as Weston Price wrote. Here are a few more tidbits to whet your appetite: K2 may affect glucose control and insulin release (1, 2). It's concentrated in the brain, serving an as yet unknown function.

Hunter-gatherers didn't have multivitamins, they had nutrient-dense food. As long as you eat a natural diet containing some vegetables and some animal products, and lay off the processed grains, sugar and vegetable oil, the micronutrients will take care of themselves.

Vitamin K2, MK-4 is only found in animal products. The best sources known are grass-fed butter from cows eating rapidly growing grass, and foie gras. K2 tends to associate with beta-carotene in butter, so the darker the color, the more K2 it contains (also, the better it tastes). Fish eggs, other grass-fed dairy, shellfish, insects and other organ meats are also good sources. Chris Masterjohn compiled a list of food sources in his excellent article on the Weston Price foundation website. I highly recommend reading it if you want more detail. K2 MK-7 is found abundantly in natto, a type of fermented soybean, and it may be partially converted to MK-4.

Finally, you can also buy K2 supplements. The best one is butter oil, the very same stuff Price used to treat his patients. I have used this one personally, and I noticed positive effects on my skin overnight. Thorne research makes a synthetic liquid K2 MK-4 supplement that is easy to dose drop-wise to get natural amounts of it. Other K2 MK-4 supplements are much more concentrated than what you could get from food so I recommend avoiding them. I am generally against supplements, but I've ordered the Thorne product for a little self-experimentation. I want to see if it has the same effect on my skin as the butter oil (update- it does).

Activator X

Activator X, the almost-mythical vitamin discovered and characterized by Weston Price, has been identified! For those of you who are familiar with Weston Price's book 'Nutrition and Physical Degeneration', you know what I'm talking about. For the rest of you, allow me to explain.

Weston Price was a dentist and scientist in the early part of the 20th century. Practicing dentistry in Cleveland, he was amazed at the poor state of his patients' teeth and the suffering it inflicted. At the time, dental health was even worse than it is today, with some children in their teens already being fitted for dentures. Being a religious man, he could not bring himself to believe that 'physical degeneration' was what God intended for mankind. He traveled throughout the world looking for cultures that did not have crooked teeth or dental decay, and that also exhibited general health and well-being. And he found them. A lot of them.

These cultures were all considered 'primitive' at the time, and were not subject to the lifestyles or food choices of the Western world. He documented, numerically and with photographs, the near-absence of dental cavities and crooked teeth in a number of different cultures throughout the world. He showed that like all animals, humans are healthy and robust when occupying the right ecological niche. Price had a deep respect for the nutritional knowledge these cultures curated.

He also documented the result when these same cultures were exposed to Western diets of white flour, sugar and other industrially processed foods: they developed rampant cavities, their children grew with crooked teeth due to narrow dental arches, as well as a number of other strikingly familiar health problems. I think it's worth mentioning that Price's findings were universally corroborated by doctors in contact with the same cultures at the time. They are also corroborated by the archaeological record. Many of his findings were published in respected peer-reviewed journals. 'Nutrition and Physical Degeneration' is required reading for anyone interested in the relationship between nutrition and health.

Naturally, Price wanted to understand what healthy diets had in common besides the absence of white flour and sugar. Having studied cultures as diverse as the carnivorous Inuit, the dairy-eating Masai and agricultural groups in the Andes, he realized that humans are capable of thriving on very diverse foods. However, he did find one thing in common: they all ate some amount of fat-soluble, animal-derived vitamins. Even the near-vegetarian groups ate insects or small animals that were rich in these vitamins. He looked for, but did not find, a single group that was entirely vegetarian and had the teeth and health of the groups he described in 'Nutrition and Physical Degeneration'.

There were three vitamins he found abundantly in the diets of healthy non-industrialized people: A, D, and an unknown substance he called 'activator X'. He considered them all to be synergistic and critical for proper mineral metabolism (tooth and bone formation and maintenance) and general health. He had a chemical test for activator X, but he didn't know its chemical structure and so it remained unidentified. He found activator X most abundantly in grass-fed butter (but not grain fed!), organ meats, shellfish, insects, and fish eggs. Many of these foods were fed preferentially to pregnant or reproductive-age women in the groups he studied.

Price used extracts from grass-fed butter (activator X), in combination with high-vitamin cod liver oil (A and D), to prevent and reverse dental cavities in many of his patients. 'Nutrition and Physical Degeneration' contains X-rays of case studies showing re-calcification of severe cavities using this combination.

After reading his book, I wasn't sure what to make of activator X. If it's so important, why hasn't it been identified in the 60+ years since he described it? I'm happy to say, it finally has. In the summer of 2007, Chris Masterjohn wrote an article for the Weston Price foundation website, in which he identified Weston Price's mystery vitamin: it's vitamin K2, specifically the MK-4 isoform (menatetrenone).

It occurs exactly where Weston Price described it, and research is beginning to find that it's also critical for mineral metabolism, bone and tooth formation and maintenance. Its function is synergistic with vitamins A and D. To illustrate the point, where do A, D and K2 MK-4 all occur together in nature? Eggs and milk, the very foods that are designed to feed a growing animal. This is true from sea urchins to humans, confirming the ubiquitous and critical role of these nutrients. K2 has not yet been recognized as such by the mainstream, but it is every bit as important to health as A and D. The scientific cutting edge is beginning to catch on, however, due to some very tantalizing studies.

In the next post, I'll go into more detail about K2, what the science is telling us and where to get it.

Exercise Didn't Keep Us From Getting Fat

One of the surprising things I noticed when I was poring over data from the NHANES survey (US CDC National Health and Nutrition Examination Survey) from 1975 to 2006 is that the number of inactive people has diminished in that same time period from 50% to 24%. This is shocking to most people. We have this romanticized idea that in the 1970s people were more active, as if everyone chopped wood and walked 15 miles to work in the morning. The reality is, there were office jobs, housewives and cars without the large numbers of runners and gym-goers we have today.

Granted, NHANES data are self-reported and should be taken with a grain of salt. However, Chris at Conditioning Research pointed me to a study looking at changes in energy expenditure from the 1980s to the present in North America and Europe. It doesn't suffer from the same biases because it's based on direct measurement rather than self-reporting. Here's the executive summary: we're expending slightly more energy than we used to, partly because we exercise more and partly because it takes more energy to move our heavier bodies around.

I'm certainly not blaming the obesity problem on an increase in physical activity, but I do think we can safely rule out inactivity as the reason we've gotten fatter. In my mind, this only leaves one major possible cause for the obesity epidemic: changes in diet. Don't get me wrong, I think exercise is good. It has numerous positive effects on physical and mental health. But it's not as powerful of a tool for fat loss and general health as diet.

Anecdotally, I do know several people who lose fat when they exercise regularly. I also know some who don't lose fat when they exercise. Exercise and a healthy diet converge on some of the same metabolic pathways, such as sensitivity to insulin. But diet changes are far more effective than exercise at correcting metabolic problems. The reason is simple: the problems a person corrects with a good diet are caused by a poor diet to begin with.

US Fructose Consumption Trends

As you may have noticed, I suspect fructose is involved in overweight and other health problems. It seems to have adverse effects on fat deposition in the liver and insulin sensitivity that could be related to its association with weight gain. I looked through USDA estimated per capita consumption of different sweeteners to get an idea of how fructose consumption has changed in the US in the time since adult obesity rates have doubled.

In 1970, we ate an estimated 72.5 lb/year of cane and beet sugar (sucrose) per person, which is 50% fructose and 50% glucose. We also ate 0.4 lb/year of corn syrup, which is most commonly 55% fructose, 45% glucose. Consumption of other unspecified sweeteners was 12.0 lb/year, for a total intake of 84.9 lb/year of added sweeteners.

In 2007, we ate an estimated 44.2 lb/year of sucrose, 40.1 lb/year of corn syrup, and 12.9 lb/year of other unspecified sweeteners, for a total added sweetener intake of 97.2 lb/year. Doing the math, and generously assuming that the "other" sweeteners are 100% honey (~50% fructose), here are the results:

• 1970: 42.5 lb/year of added fructose.

• 2007: 50.6 lb/year of added fructose.

At 19%, it's not a staggering increase, but it's definitely significant. I also think it's an underestimate, because it doesn't include fruit juice or total fruit consumption, both of which have increased. Other notable findings: grain intake has increased 41% between 1970 and 2005, due chiefly to rising consumption of processed wheat products. Added fats and oils have increased 63% in the same time period, with the increase coming exclusively from vegetable fats. The use of hydrogenated shortening has more than doubled.

What has caused the dramatic expansion of American waistlines in the last 30 years? No one knows for sure, but I think it's probably related to diet since the percentage of people who exercise has actually increased in the same time period. My money is on the wheat and sugar, with possible contributions from hydrogenated oil, polyunsaturated vegetable oils and chemical pollutants. The reason is that wheat and sugar seem to have devastating metabolic effects on populations throughout the world, such as the Pima.

Lessons From the Pima Indians

At 38% and climbing in 2006, the Pima indians (Akimel O'odham) of Arizona have the highest rate of diabetes of any population in the world. They also have staggering rates of obesity (~70%) and hypertension.

Things were very different for them before 1539, when the Spanish first made contact. They lived on an agricultural diet of beans, corn and squash, with wild fish, game meat and plants. As with most native people, they were thin and healthy while on their traditional diet.

In 1859, the Pima were restricted to a small fraction of their original land along the Gila river, the Pima Reservation. In 1866, settlers began arriving in the region and diverting the Gila river upstream of the reservation for their own agriculture. In 1869, the river went dry for the first time. 1886 was the last year any water flowed to the Pima Reservation in the Gila river.

The Pima had no way to obtain water, and no way to grow crops. Their once productive subsistence economy ground to a halt. Famine ensued for 40 desperate years. The Pima cut down their extensive mesquite forests to sell for food and water. Eventually, after public outcry, uncle Sam stepped in.

The government provided the Pima with subsidized "food": white flour, sugar, partially hydrogenated lard, and canned goods. They promptly became diabetic and overweight, and have remained that way ever since.

The Pima are poster children for mainstream nutrition researchers in the US for several reasons. First of all, their pre-contact diet was probably fairly low in fat, and researchers love to point out that they now eat more fat (comparable to the average American diet). Another reason is that there's another group of Pima in Mexico who still live on a relatively traditional diet and are much healthier. They are genetically very similar, supporting the idea that it's the lifestyle of the American Pima that's causing their problems. The third reason is that the Mexican Pima exercise more than the Arizona Pima and eat a bit less.

I of course agree with the conclusion that their lifestyle is behind their problems; that's pretty obvious. I think most Pima know it too. If they got their water back, maybe things would be different for them.

However, the focus on macronutrients sometimes obscures the fact that the modern Pima diet is pure crap. It's mostly processed food with a low nutrient density. It also contains the two biggest destroyers of indigenous health: white flour and sugar. There are numerous examples of cultures going from a high-fat diet to a lower-fat "reservation food" diet and suffering the same fate: the Inuit of Alaska, the Maasai and Samburu of Kenya, tribes in the Pacific Northwestern US and Canada, certain Aboriginal groups, and more. What do they all have in common? White flour, sugar and other processed food.

The exercise thing is somewhat questionable as well. True, Mexican Pima exercise 2.5 times more than Arizona Pima, but the Arizona Pima still exercise much more than the average American! Women clock in at 3.1 hours a week, while men come in at a whopping 12.1 hours a week! I am a bike commuter and weight lifter, and even I don't exercise that much. So forgive me if I'm a little skeptical of the idea that they aren't exercising enough to keep the weight off. 

The history of the Pima is a heart-wrenching story that has been repeated hundreds, perhaps thousands of times all over the world. Europeans bring in white flour, sugar and other processed food, it destroys a native populations' health, and then researchers either act like they don't understand why it happened, or give unsatisfying explanations for it.

The Pima are canaries in the coal mine, and we can learn a lot from them. Their health problems resemble those of other poor Americans (and wealthier ones also, to a lesser extent). This is because they are both eating similar types of things. The problem is creeping into society at large, however, as we rely more and more on processed wheat, corn, soy and sugar, and less on wholesome food. Obesity in the US has doubled in the past 30 years, and childhood obesity has tripled. Diabetes is following suit. Life expectancy has begun to diminish in some (poor) parts of the country. Meanwhile, our diet is looking increasingly like Pima reservation food. It's time to learn a lesson from their tragedy.

Leptin

I've been puzzled by an interesting question lately. Why is it that certain cultures are able to eat large amounts of carbohydrate and remain healthy, while others suffer from overweight and disease? How do the pre-industrial Kuna and Kitavans maintain their insulin sensitivity while their bodies are being bombarded by an amount of carbohydrate that makes the average American look like a bowling ball?

I read a very interesting post on the Modern Forager yesterday that sent me on a nerd safari through the scientific literature. The paper that inspired the Modern Forager post is a review by Dr. Staffan Lindeberg. In it, he attempts to draw a link between compounds called lectins, found in grains (among other things), and resistance to the hormone leptin. Let's take a step back and go over some background.

One of the most-studied animal models of obesity is called the "Zucker" rat. This rat has a missense mutation in its leptin receptor gene, causing it to be nonfunctional. Leptin is a hormone that signals satiety, or fullness. It's secreted by fat tissue. The more fat tissue an animal has, the more leptin it secretes. Normally, this creates negative feedback that causes it to eat less when fat begins to accumulate, keeping its weight within a narrow range.

Zucker rats secrete leptin just fine, but they lack leptin receptors in their brain. Their blood leptin is high but their brain isn't listening. Thus, the signal to stop eating never gets through and they eat themselves to morbid obesity. Cardiovascular disease and diabetes follow shortly thereafter, unless you remove their visceral fat surgically.

The reason Zucker rats are so interesting is they faithfully reproduce so many features of the disease of civilization in humans. They become obese, hypometabolic, develop insulin resistance, impaired glucose tolerance, dyslipidemia, diabetes, and cardiovascular disease. Basically, severe metabolic syndrome. So here's a rat that shows that leptin resistance can cause something that looks a whole heck of a lot like the disease of civilization in humans.

For this model to be relevant to us, we'd expect that humans with metabolic syndrome should be leptin-resistant. Well what do you know, administering leptin to obese people doesn't cause satiety like it does in thin people. Furthermore, elevated leptin predicts the onset of obesity and metabolic syndrome. It also predicts insulin resistance. Yes, you read that right, leptin resistance may come before insulin resistance.

Interestingly enough, the carbohydrate-loving Kitavans don't get elevated leptin like europeans do, and they don't become overweight, develop insulin dysfunction or the metabolic syndrome either. This all suggests that leptin may be the keystone in the whole disease process, but what accounts for the differences in leptin levels between populations?

Thoughts on Obesity, Part I

From the US Centers for Disease Control website:

Since the mid-seventies, the prevalence of overweight and obesity has increased sharply for both adults and children. Data from two NHANES surveys show that among adults aged 20–74 years the prevalence of obesity increased from 15.0% (in the 1976–1980 survey) to 32.9% (in the 2003–2004 survey).

In hunter-gatherer and some semi-agricultural societies, obesity is rare. In most, it's nonexistent. Wild animals typically do not accumulate enough fat to interfere with vigorous exercise, and when they do, it's because they're about to hibernate or migrate. Wild animals also tend to have similar amounts of body fat between individuals (at a given age and sex), unlike industrialized humans. This makes me think that obesity is an unnatural effect of our current lifestyle. Whatever the cause, it's getting progressively more common.

According to certain nutrition experts, we know exactly what causes overweight. It's a character flaw known as overeating. Calories in, calories out. And the cure is to eat less. The problem is, this treatment has a poor record of efficacy.

Restricting calories is also fraught with problems. Each person's metabolism has a preference for a specific body composition within the context of a particular lifestyle. If total calories are restricted without changing diet composition, the body reacts vigorously to maintain homeostasis. Energy expenditure is reduced; muscle and organ mass diminish. The psychological effects are particularly bad, as anyone can tell you who has been on a low-calorie diet. In 1944, Ancel Keys undertook a calorie restriction trial in conscientious objector "volunteers" in Minnesota. They remained on a 1,570-calorie diet that was low in fat and protein and high in carbohydrate, for 24 weeks. Hardly a draconian calorie count. Here's a quote from the study:

As starvation progressed, fewer and fewer things could stimulate the men to overt action. They described their increasing weakness, loss of ambition, narrowing of interests, depression, irritability, and loss of libido as a pattern characteristic of "growing old".

Some of the men ended up suffering from neurosis and borderline psychosis before the end of the study, one culminating in self-mutilation. This is what we're being prescribed for weight loss?

There are some diet trends that have associated with rising obesity in the US. Per capita calorie consumption has increased. This increase is due to a higher consumption of carbohydrate. Total protein and fat consumption have been almost identical for the past 30 years. This period also saw increases in the consumption of unsaturated vegetable oils, hydrogenated vegetable oils and high-fructose corn syrup. It's hard to say from this association which of these factors (if any) has caused us to gain weight in the last 30 years, but it certainly isn't total fat or protein. Fortunately, we have other clues.

Say Hello to the Kuna

For those of you who haven't been reading the comments, we've been having a spirited discussion about the diet and health of hunter-gatherers here. I brought up the Kuna indians in Panama, who are immune to hypertension, live a good long time, do not gain excess weight, and seem to have less cardiovascular disease and cancer than their city-dwelling cousins.

I was hungry for more information about the Kuna lifestyle, so over the last few days, I've dug up every paper I could find on them. The first paper describing their lack of hypertension was published in 1944 and I don't have access to the full text. In 1997, a series of studies began, headed by Dr. Norman Hollenberg at Harvard. He confirmed the blood pressure findings, and collected data on their diet, lifestyle and kidney function. Here's a summary:

The Kuna are half hunter-gatherers, half agricultural. They cultivate plantains, corn, cocoa, yucca, kidney beans, and several types of fruit. They trade for sugar, salt, some processed cocoa and miscellaneous other foods. They drink 40+ oz of hot cacao/cocoa per day, some locally produced and some imported. A little-known secret: the Kuna eat an average of 3 oz of donut a week. They also fish and hunt regularly.

In the first recent study, published in 1997, the Kuna diet is described as 29% lower in fat than the average US diet (56 g/day), 23% lower in protein (12.2 g), 60% higher in cholesterol, and higher in sodium and fiber. The study doesn't specifically mention this, but the reader is left to infer that 65% of their calories come from carbohydrate. This would be from plantains, corn, yucca, sugar and beans. The fat in their diet comes almost exclusively from coconut, cocoa and fish: mostly saturated and omega-3 fats.

In the next study, the picture is slightly different. Their staple stew, tule masi, is described as being 38% fat by calories (from coconut and fish), exceeding the American average. In the final study in 2006, Hollenberg's group used a more precise method of accounting for diet composition than was used in previous attempts. The paper doesn't report macronutrients as a percentage of calories however.

I was able to find some clues about their diet composition. First of all, they report the meat consumption of the Kuna at approximately 60 oz per week, mostly from fish. That's 8.6 oz per day, identical to the American average.

By putting together the pieces from the later studies, a new picture emerges: a diet high in fish and moderate in protein, moderate in unprocessed fat (especially saturated and omega-3), and moderately high in mostly unprocessed carbohydrate.

Here's my interpretation. The Kuna are healthier than their city-dwelling cousins for a number of reasons. They have a very favorable omega3:6 ratio due to seafood, wild game and relatively saturated vegetable fats. Their carbohydrate foods are mostly unprocessed and mostly from non-grain sources. They also live an outdoor life full of sunshine (vitamin D) and exercise. The chocolate may also contribute to their health, as it contains high levels of potentially protective polyphenols. They're healthier than industrialized people because they live more naturally.

Another lesson to be learned from the Kuna and other exceptionally healthy indigenous peoples is that the human body can tolerate a large amount of carbohydrate under the right conditions. 

Convenience Store Survival Training

I was on the road yesterday driving to a county court to defend myself (unsuccessfully) against a speeding ticket. I reluctantly stopped into a convenience store on my way back, to see if there was anything I would eat for lunch.

I actually did find two things that were palatable and not too unhealthy: canned sardines and toasted cashews. The total was $2.50, affordable even for a grad student.

The sardines were canned in "tomato sauce", which I realized later contained soybean oil. Oops. Well I suppose when you get your food at a convenience store, you have to expect such things.

The main thing that bothered me was the trash. I posted a mugshot (above) of the can, fork and plastic bag that I either trashed or recycled as a result of the meal. The total volume of trash was probably almost as much as the total volume of food.

I think if you stick to nuts, canned fish and fresh fruit, it's possible to survive a convenience store stop. And Baby Ruths. Those are healthy, right?