Paleolithic Diet Clinical Trials, Part V

Dr. Staffan Lindeberg's group has published a new paleolithic diet paper in the journal Nutrition and Metabolism, titled "A Paleolithic Diet is More Satiating per Calorie than a Mediterranean-like Diet in Individuals with Ischemic Heart Disease" (1).

The data in this paper are from the same intervention as his group's 2007 paper in Diabetologia (2). To review the results of this paper, 12 weeks of a Paleolithic-style diet caused impressive fat loss and improvement in glucose tolerance, compared to 12 weeks of a Mediterranean-style diet, in volunteers with pre-diabetes or diabetes and ischemic heart disease. Participants who started off with diabetes ended up without it. A Paleolithic diet excludes grains, dairy, legumes and any other category of food that was not a major human food source prior to agriculture. I commented on this study a while back (3, 4).

One of the most intriguing findings in his 2007 study was the low calorie intake of the Paleolithic group. Despite receiving no instruction to reduce calorie intake, the Paleolithic group only ate 1,388 calories per day, compared to 1,823 calories per day for the Mediterranean group*. That's a remarkably low ad libitum calorie intake in the former (and a fairly low intake in the latter as well).

With such a low calorie intake over 12 weeks, you might think the Paleolithic group was starving. Fortunately, the authors had the foresight to measure satiety, or fullness, in both groups during the intervention. They found that satiety was almost identical in the two groups, despite the 24% lower calorie intake of the Paleolithic group. In other words, the Paleolithic group was just as full as the Mediterranean group, despite a considerably lower intake of calories. This implies to me that the body fat "set point" decreased, allowing a reduced calorie intake while body fat stores were burned to make up the calorie deficit. I suspect it also decreased somewhat in the Mediterranean group, although we can't know for sure because we don't have baseline satiety data for comparison.

There are a few possible explanations for this result. The first is that the Paleolithic group was eating more protein, a highly satiating macronutrient. However, given the fact that absolute protein intake was scarcely different between groups, I think this is unlikely to explain the reduced calorie intake.

A second possibility is that certain potentially damaging Neolithic foods (e.g., wheat and refined sugar) interfere with leptin signaling**, and removing them lowers fat mass by allowing leptin to function correctly. Dr. Lindeberg and colleagues authored a hypothesis paper on this topic in 2005 (5).

A third possibility is that a major dietary change of any kind lowers the body fat setpoint and reduces calorie intake for a certain period of time. In support of this hypothesis, both low-carbohydrate and low-fat diet trials show that overweight people spontaneously eat fewer calories when instructed to modify their diets in either direction (6, 7). More extreme changes may cause a larger decrease in calorie intake and fat mass, as evidenced by the results of low-fat vegan diet trials (8, 9). Chris Voigt's potato diet also falls into this category (10, 11). I think there may be something about changing food-related sensory cues that alters the defended level of fat mass. A similar idea is the basis of Seth Roberts' book The Shangri-La Diet.

If I had to guess, I would think the second and third possibilities contributed to the finding that Paleolithic dieters lost more fat without feeling hungry over the 12 week diet period.


*Intakes were determined using 4-day weighed food records.

**Leptin is a hormone produced by body fat that reduces food intake and increases energy expenditure by acting in the brain. The more fat a person carries, the more leptin they produce, and hypothetically this should keep body fat in a narrow window by this form of "negative feedback". Clearly, that's not the whole story, otherwise obesity wouldn't exist. A leading hypothesis is that resistance to the hormone leptin causes this feedback loop to defend a higher level of fat mass.

Book Review: The Primal Blueprint

Mark Sisson has been a central figure in the evolutionary health community since he began his weblog Mark's Daily Apple in 2006. He and his staff have been posting daily on his blog ever since. He has also written several other books, edited the Optimum Health newsletter, competed as a high-level endurance athlete, and served on the International Triathlon Union as the anti-doping chairman, all of which you can read about on his biography page. Mark is a practice-what-you-preach kind of guy, and if physical appearance means anything, he's on to something.

In 2009, Mark published his long-awaited book The Primal Blueprint. He self-published the book, which has advantages and disadvantages. The big advantage is that you aren't subject to the sometimes onerous demands of publishers, who attempt to maximize sales at Barnes and Noble. The front cover sports a simple picture of Mark, rather than a sunbaked swimsuit model, and the back cover offers no ridiculous claims of instant beauty and fat loss.

The drawback of self-publishing is it's more difficult to break into a wider market. That's why Mark has asked me to publish my review of his book today. He's trying to push it up in the Amazon.com rankings so that it gets a broader exposure. If you've been thinking about buying Mark's book, now is a good time to do it. If you order it from Amazon.com on March 17th, Mark is offering to sweeten the deal with some freebies on his site Mark's Daily Apple. Full disclosure: I'm not getting anything out of this, I'm simply mentioning it because I was reviewing Mark's book anyway and I thought some readers might enjoy it.

The Primal Blueprint is not a weight loss or diet book, it's a lifestyle program with an evolutionary slant. Mark uses the example of historical and contemporary hunter-gatherers as a model, and attempts to apply those lessons to life in the 21st century. He does it in a way that's empowering accessible to nearly everyone. To illustrate his points, he uses the example of an archetypal hunter-gatherer called Grok, and his 21st century mirror image, the Korg family.

The diet section will be familiar to anyone who has read about "paleolithic"-type diets. He advocates eating meats including organs, seafood, eggs, nuts, abundant vegetables, and fruit. He also suggests avoiding grains, legumes, dairy (although he's not very militant about this one), processed food in general, and reducing carbohydrate to less than 150 grams per day. I like his diet suggestions because they focus on real food. Mark is not a drill sergeant. He tries to create a plan that will be sustainable in the long run, by staying positive and allowing for cheats.

We part ways on the issue of carbohydrate. He suggests that eating more than 150 grams of carbohydrate per day leads to fat gain and disease, whereas I feel that position is untenable in light of what we know of non-industrial cultures (including some relatively high-carbohydrate hunter-gatherers). Although carbohydrate restriction (or at least wheat and sugar restriction) does have its place in treating obesity and metabolic dysfunction in modern populations, ultimately I don't think it's necessary for the prevention of those same problems, and it can even be counterproductive in some cases. Mark does acknowledge that refined carbohydrates are the main culprits.

The book's diet section also recommends nutritional supplements, including a multivitamin/mineral, antioxidant supplement, probiotics, protein powder and fish oil. I'm not a big proponent of supplementation. I'm also a bit of a hypocrite because I do take small doses of fish oil (when I haven't had seafood recently), and vitamin D in wintertime. But I can't get behind protein powders and antioxidant supplements.

Mark's suggestions for exercise, sun exposure, sleep and stress management make good sense to me. In a nutshell: do all three, but keep the exercise varied and don't overdo it. As a former high-level endurance athlete, he has a lot of credibility here. He puts everything in a format that's practical, accessible and empowering.

I think The Primal Blueprint is a useful book for a person who wants to maintain or improve her health. Although we disagree on the issue of carbohydrate, the diet and lifestyle advice is solid and will definitely be a vast improvement over what the average person is doing. The Primal Blueprint is not an academic book, nor does it attempt to be. It doesn't contain many references (although it does contain some), and it won't satisfy someone looking for an in-depth discussion of the scientific literature. However, it's perfect for someone who's getting started and needs guidance, or who simply wants a more comprehensive source than reading blog snippets. It would make a great gift for that family member or friend who's been asking how you stay in such good shape.

Lindeberg on Obesity

I'm currently reading Dr. Staffan Lindeberg's magnum opus Food and Western Disease, recently published in English for the first time. Dr. Lindeberg is one of the world's leading experts on the health and diet of non-industrial cultures, particularly in Papua New Guinea. The book contains 2,034 references. It's also full of quotable statements. Here's what he has to say about obesity:

Middle-age spread is a normal phenomenon - assuming you live in the West. Few people are able to maintain their [youthful] waistline after age 50. The usual explanation - too little exercise and too much food - does not fully take into account the situation among traditional populations. Such people are usually not as physically active as you may think, and they usually eat large quantities of food.

Overweight has been extremely rare among hunter-gatherers and other traditional cultures [18 references]. This simple fact has been quickly apparent to all foreign visitors...

The Kitava study measured height, weight, waist circumference, subcutaneous fat thickness at the back of the upper arm (triceps skinfold) and upper arm circumference on 272 persons ages 4-86 years. Overweight and obesity were absent and average [body mass index] was low across all age groups. ...no one was larger around their waist than around their hips.

...The circumference of the upper arm [mostly indicating muscle mass] was only negligibly smaller on Kitava [compared with Sweden], which indicates that there was no malnutrition. It is obvious from our investigations that lack of food is an unknown concept, and that the surplus of fruits and vegetables regularly rots or is eaten by dogs.

The Population of Kitava occupies a unique position in the world in terms of the negligible effect that the Western lifestyle has had on the island.

The only obese Kitavans Dr. Lindeberg observed were two people who had spent several years off the island living a modern, urban lifestyle, and were back on Kitava for a visit.

I'd recommend this book to anyone who has a scholarly interest in health and nutrition, and somewhat of a background in science and medicine. It's extremely well referenced, which makes it much more valuable.

The Body Fat Setpoint, Part IV: Changing the Setpoint

Prevention is Easier than Cure

Experiments in animals have confirmed what common sense suggests: it's easier to prevent health problems than to reverse them. Still, many health conditions can be improved, and in some cases reversed, through lifestyle interventions. It's important to have realistic expectations and to be kind to oneself. Cultivating a drill sergeant mentality will not improve quality of life, and isn't likely to be sustainable.

Fat Loss: a New Approach

If there's one thing that's consistent in the medical literature, it's that telling people to eat fewer calories does not help them lose weight in the long term. Gary Taubes has written about this at length in his book Good Calories, Bad Calories, and in his upcoming book on body fat. Many people who use this strategy see transient fat loss, followed by fat regain and a feeling of defeat. There's a simple reason for it: the body doesn't want to lose weight. It's extremely difficult to fight the fat mass setpoint, and the body will use every tool it has to maintain its preferred level of fat: hunger, reduced body temperature, higher muscle efficiency (i.e., less energy is expended for the same movement), lethargy, lowered immune function, et cetera.

Therefore, what we need for sustainable fat loss is not starvation; we need a treatment that lowers the fat mass setpoint. There are several criteria that this treatment will have to meet to qualify:

1. It must cause fat loss
2. It must not involve deliberate calorie restriction
3. It must maintain fat loss over a long period of time
4. It must not be harmful to overall health
   

I also prefer strategies that make sense from the perspective of human evolution.

Strategies: Diet Pattern

The most obvious treatment that fits all of my criteria is low-carbohydrate dieting. Overweight people eating low-carbohydrate diets generally lose fat and spontaneously reduce their calorie intake. In fact, in several diet studies, investigators compared an all-you-can-eat low-carbohydrate diet with a calorie-restricted low-fat diet. The low-carbohydrate dieters generally reduced their calorie intake and body fat to a similar or greater degree than the low-fat dieters, despite the fact that they ate all the calories they wanted (1). This suggest that their fat mass setpoint had changed. At this point, I think moderate carbohydrate restriction may be preferable to strict carbohydrate restriction for some people, due to the increasing number of reports I've read of people doing poorly in the long run on extremely low-carbohydrate diets (2).

Another strategy that appears effective is the "paleolithic" diet. In Dr. Staffan Lindeberg's 2007 diet study, overweight volunteers with heart disease lost fat and reduced their calorie intake to a remarkable degree while eating a diet consistent with our hunter-gatherer heritage (3). This result is consistent with another diet trial of the paleolithic diet in diabetics (4). In post hoc analysis, Dr. Lindeberg's group showed that the reduction in weight was apparently independent of changes in carbohydrate intake*. This suggests that the paleolithic diet has health benefits that are independent of carbohydrate intake.

Strategies: Gastrointestinal Health

Since the gastrointestinal (GI) tract is so intimately involved in body fat metabolism and overall health (see the former post), the next strategy is to improve GI health. There are a number of ways to do this, but they all center around four things:

1. Don't eat food that encourages the growth of harmful bacteria
2. Eat food that encourages the growth of good bacteria
3. Don't eat food that impairs gut barrier function
4. Eat food that promotes gut barrier health

The first one is pretty easy: avoid refined sugar, refined carbohydrate in general, and lactose if you're lactose intolerant. For the second and fourth points, make sure to eat fermentable fiber. In one trial, oligofructose supplements led to sustained fat loss, without any other changes in diet (5). This is consistent with experiments in rodents showing improvements in gut bacteria profile, gut barrier health, glucose tolerance and body fat mass with oligofructose supplementation (6, 7, 8).

Oligofructose is similar to inulin, a fiber that occurs naturally in a wide variety of plants. Good sources are jerusalem artichokes, jicama, artichokes, onions, leeks, burdock and chicory root. Certain non-industrial cultures had a high intake of inulin. There are some caveats to inulin, however: inulin and oligofructose can cause gas, and can also exacerbate gastroesophageal reflux disorder (9). So don't eat a big plate of jerusalem artichokes before that important date.

The colon is packed with symbiotic bacteria, and is the site of most intestinal fermentation. The small intestine contains fewer bacteria, but gut barrier function there is critical as well. The small intestine is where the GI doctor will take a biopsy to look for celiac disease. Celiac disease is a degeneration of the small intestinal lining due to an autoimmune reaction caused by gluten (in wheat, barley and rye). This brings us to one of the most important elements of maintaining gut barrier health: avoiding food sensitivities. Gluten and casein (in dairy protein) are the two most common offenders. Gluten sensitivity is widespread and typically undiagnosed (10).

Eating raw fermented foods such as sauerkraut, kimchi, yogurt and half-sour pickles also helps maintain the integrity of the upper GI tract. I doubt these have any effect on the colon, given the huge number of bacteria already present. Other important factors in gut barrier health are keeping the ratio of omega-6 to omega-3 fats in balance, eating nutrient-dense food, and avoiding the questionable chemical additives in processed food. If triglycerides are important for leptin sensitivity, then avoiding sugar and ensuring a regular source of omega-3 should aid weight loss as well.

Strategies: Micronutrients

As I discussed in the last post, micronutrient deficiency probably plays a role in obesity, both in ways that we understand and ways that we (or I) don't. Eating a diet that has a high nutrient density and ensuring a good vitamin D status will help any sustainable fat loss strategy. The easiest way to do this is to eliminate industrially processed foods such as white flour, sugar and seed oils. These constitute more than 50% of calories for the average Westerner.

After that, you can further increase your diet's nutrient density by learning to properly prepare grains and legumes to maximize their nutritional value and digestibility (11, 12; or by avoiding grains and legumes altogether if you wish), selecting organic and/or pasture-raised foods if possible, and eating seafood including seaweed. One of the problems with extremely low-carbohydrate diets is that they may be low in water-soluble micronutrients, although this isn't necessarily the case.

Strategies: Miscellaneous

In general, exercise isn't necessarily helpful for fat loss. However, there is one type of exercise that clearly is: high-intensity intermittent training (HIIT). It's basically a fancy name for sprints. They can be done on a track, on a stationary bicycle, using weight training circuits, or any other way that allows sufficient intensity. The key is to achieve maximal exertion for several brief periods, separated by rest. This type of exercise is not about burning calories through exertion: it's about increasing hormone sensitivity using an intense, brief stressor (hormesis). Even a ridiculously short period of time spent training HIIT each week can result in significant fat loss, despite no change in diet or calorie intake (13).

Anecdotally, many people have had success using intermittent fasting (IF) for fat loss. There's some evidence in the scientific literature that IF and related approaches may be helpful (14). There are different approaches to IF, but a common and effective method is to do two complete 24-hour fasts per week. It's important to note that IF isn't about restricting calories, it's about resetting the fat mass setpoint. After a fast, allow yourself to eat quality food until you're no longer hungry.

Insufficient sleep has been strongly and repeatedly linked to obesity. Whether it's a cause or consequence of obesity I can't say for sure, but in any case it's important for health to sleep until you feel rested. If your sleep quality is poor due to psychological stress, meditating before bedtime may help. I find that meditation has a remarkable effect on my sleep quality. Due to the poor development of oral and nasal structures in industrial nations, many people do not breathe effectively and may suffer from conditions such as sleep apnea that reduce sleep quality. Overweight also contributes to these problems.

I'm sure there are other useful strategies, but that's all I have for now. If you have something to add, please put it in the comments.


* Since reducing carbohydrate intake wasn't part of the intervention, this result is observational.

Paleo is Going Mainstream

There was an article on the modern "Paleolithic" lifestyle in the New York Times today. I thought it was a pretty fair treatment of the subject, although it did paint it as more macho and carnivorous than it needs to be. It features three attractive NY cave people. It appeared in the styles section here. Paleo is going mainstream. We can expect media health authorities to start getting defensive about it any minute now.

What's the Ideal Fasting Insulin Level?

Insulin is an important hormone. Its canonical function is to signal cells to absorb glucose from the bloodstream, but it has many other effects. Chronically elevated insulin is a marker of metabolic dysfunction, and typically accompanies high fat mass, poor glucose tolerance (prediabetes) and blood lipid abnormalities. Measuring insulin first thing in the morning, before eating a meal, reflects fasting insulin. High fasting insulin prevents the escape of fat from fat tissue and causes a number of other metabolic disturbances.

Elevated fasting insulin is a hallmark of the metabolic syndrome, the quintessential modern metabolic disorder that affects 24% of Americans (NHANES III). Dr. Lamarche and colleagues found that having an insulin level of 13 uIU/mL in Canada correlated with an 8-fold higher heart attack risk than a level of 9.3 uIU/mL (1; thanks to NephroPal for the reference). So right away, we can put our upper limit at 9.3 uIU/mL. The average insulin level in the U.S., according to the NHANES III survey, is 8.8 uIU/mL for men and 8.4 for women (2). Given the degree of metabolic dysfunction in this country, I think it's safe to say that the ideal level of fasting insulin is probably below 8.4 uIU/mL as well.

Let's dig deeper. What we really need is a healthy, non-industrial "negative control" group. Fortunately, Dr. Staffan Lindeberg and his team made detailed measurements of fasting insulin while they were visiting the isolated Melanesian island of Kitava (3). He compared his measurements to age-matched Swedish volunteers. In male and female Swedes, the average fasting insulin ranges from 4-11 uIU/mL, and increases with age. From age 60-74, the average insulin level is 7.3 uIU/mL.

In contrast, the range on Kitava is 3-6 uIU/mL, which does not increase with age. In the 60-74 age group, in both men and women, the average fasting insulin on Kitava is 3.5 uIU/mL. That's less than half the average level in Sweden and the U.S. Keep in mind that the Kitavans are lean and have an undetectable rate of heart attack and stroke.

Another example from the literature are the Shuar hunter-gatherers of the Amazon rainforest. Women in this group have an average fasting insulin concentration of 5.1 uIU/mL (4; no data was given for men).

I found a couple of studies from the early 1970s as well, indicating that African pygmies and San bushmen have rather high fasting insulin. Glucose tolerance was excellent in the pygmies and poor in the bushmen (5, 6, free full text). This may reflect differences in carbohydrate intake. San bushmen consume very little carbohydrate during certain seasons, and thus would likely have glucose intolerance during that period. There are three facts that make me doubt the insulin measurements in these older studies:

1. It's hard to be sure that they didn't eat anything prior to the blood draw.
2. From what I understand, insulin assays were variable and not standardized back then.
   
3. In the San study, their fasting insulin was 1/3 lower than the Caucasian control group (10 vs. 15 uIU/mL). I doubt these active Caucasian researchers really had an average fasting insulin level of 15 uIU/mL. Both sets of measurements are probably too high.
   

Now you know the conflicting evidence, so you're free to be skeptical if you'd like.

We also have data from a controlled trial in healthy urban people eating a "paleolithic"-type diet. On a paleolithic diet designed to maintain body weight (calorie intake had to be increased substantially to prevent fat loss during the diet), fasting insulin dropped from an average of 7.2 to 2.9 uIU/mL in just 10 days. The variation in insulin level between individuals decreased 9-fold, and by the end, all participants were close to the average value of 2.9 uIU/mL. This shows that high fasting insulin is correctable in people who haven't yet been permanently damaged by the industrial diet and lifestyle. The study included men and women of European, African and Asian descent (7).

One final data point. My own fasting insulin, earlier this year, was 2.3 uIU/mL. I believe it reflects a good diet, regular exercise, sufficient sleep, a relatively healthy diet growing up, and the fact that I managed to come across the right information relatively young. It does not reflect: carbohydrate restriction, fat restriction, or saturated fat restriction. Neither does the low fasting insulin of healthy non-industrial cultures.

So what's the ideal fasting insulin level? My current feeling is that we can consider anything between 2 and 6 uIU/mL within our evolutionary template, although the lower half of that range may be preferable.

Paleolithic Diet Clinical Trials Part IV

Dr. Staffan Lindeberg has published a new study using the "paleolithic diet" to treat type II diabetics (free full text). Type II diabetes, formerly known as late-onset diabetes until it began appearing in children, is typically thought to develop as a result of insulin resistance (a lowered tissue response to the glucose-clearing function of insulin). This is often followed by a decrease in insulin secretion due to degeneration of the insulin-secreting pancreatic beta cells.

After Dr. Lindeberg's wild success treating patients with type II diabetes or glucose intolerance, in which he normalized the glucose tolerance of all 14 of his volunteers in 12 weeks, he set out to replicate the experiment. This time, he began with 13 men and women who had been diagnosed with type II diabetes for an average of 9 years.

Patients were put on two different diets for 3 months each. The first was a "conventional diabetes diet". I read a previous draft of the paper in which I believe they stated it was based on American Diabetes Association guidelines, but I can't find that statement in the final draft. In any case, here are the guidelines from the methods section:

The information on the Diabetes diet stated that it should aim at evenly distributed meals with increased intake of vegetables, root vegetables, dietary fiber, whole-grain bread and other whole-grain cereal products, fruits and berries, and decreased intake of total fat with more unsaturated fat. The majority of dietary energy should come from carbohydrates from foods naturally rich in carbohydrate and dietary fiber. The concepts of glycemic index and varied meals through meal planning by the Plate Model were explained [18]. Salt intake was recommended to be kept below 6 g per day.

The investigators gave the paleolithic group the following advice:

The information on the Paleolithic diet stated that it should be based on lean meat, fish, fruit, leafy and cruciferous vegetables, root vegetables, eggs and nuts, while excluding dairy products, cereal grains, beans, refined fats, sugar, candy, soft drinks, beer and extra addition of salt. The following items were recommended in limited amounts for the Paleolithic diet: eggs (≤2 per day), nuts (preferentially walnuts), dried fruit, potatoes (≤1 medium-sized per day), rapeseed or olive oil (≤1 tablespoon per day), wine (≤1 glass per day). The intake of other foods was not restricted and no advice was given with regard to proportions of food categories (e.g. animal versus plant foods). The evolutionary rationale for a Paleolithic diet and potential benefits were explained.

Neither diet was restricted in calories. After comparing the effects of the two diets for 3 months, the investigators concluded that the paleolithic diet:

• Reduced HbA1c more than the diabetes diet (a measure of average blood glucose)
• Reduced weight, BMI and waist circumference more than the diabetes diet
• Lowered blood pressure more than the diabetes diet
  
• Reduced triglycerides more than the diabetes diet
• Increased HDL more than the diabetes diet

However, the paleolithic diet was not a cure-all. At the end of the trial, 8 out of 13 patents still had diabetic blood glucose after an oral glucose tolerance test (OGTT). This is compared to 9 out of 13 for the diabetes diet. Still, 5 out of 13 with "normal" OGTT after the paleolithic diet isn't bad. The paleolithic diet also significantly reduced insulin resistance and increased glucose tolerance, although it didn't do so more than the diabetes diet.

As has been reported in other studies, paleolithic dieters ate fewer total calories than the comparison group. This is part of the reason why I believe that something in the modern diet causes hyperphagia, or excessive eating. According to the paleolithic diet studies, this food or combination of foods is neolithic, and probably resides in grains, refined sugar and/or dairy. I have my money on wheat and sugar, with a probable long-term contribution from industrial vegetable oils as well.

Were the improvements on the paleolithic diet simply due to calorie restriction? Maybe, but keep in mind that neither group was told to restrict its caloric intake. The reduction in caloric intake occurred naturally, despite the participants presumably eating to fullness. I suspect that the paleolithic diet reset the dieters' body fat set-point, after which fat began pouring out of their fat tissue. They were supplementing their diets with body fat-- 13 pounds (6 kg) of it over 3 months.

The other notable difference between the two diets, besides food types, was carbohydrate intake. The diabetes diet group ate 56% more carbohydrate than the paleo diet group, with 42% of their calories coming from it. The paleolithic group ate 32% carbohydrate. Could this have been the reason for the better outcome of the paleolithic group? I'd be surprised if it wasn't a factor. Advising a diabetic to eat a high-carbohydrate diet is like asking someone who's allergic to bee stings to fetch you some honey from your bee hive. Diabetes is a disorder of glucose intolerance. Starch is a glucose polymer.

Although to be fair, participants on the diabetes diet did improve in a number of ways. There's something to be said for eating whole foods.

This trial was actually a bit of a disappointment for me. I was hoping for a slam dunk, similar to Lindeberg's previous study that "cured" all 14 patients of glucose intolerance in 3 months. In the current study, the paleolithic diet left 8 out of 13 patients diabetic after 3 months. What was the difference? For one thing, the patients in this study had well-established diabetes with an average duration of 9 years. As Jenny Ruhl explains in her book Blood Sugar 101, type II diabetes often progresses to beta cell loss, after which the pancreas can no longer secrete an adequate amount of insulin.

This may be the critical finding of Dr. Lindeberg's two studies: type II diabetes can be prevented when it's caught at an early stage, such as pre-diabetes, whereas prolonged diabetes may cause damage that cannot be completely reversed though diet. I think this is consistent with the experience of many diabetics who have seen an improvement but not a cure from changes in diet. Please add any relevant experiences to the comments.

Collectively, the evidence from clinical trials on the "paleolithic diet" indicate that it's a very effective treatment for modern metabolic dysfunction, including excess body fat, insulin resistance and glucose intolerance. Another way of saying this is that the modern industrial diet causes metabolic dysfunction.

Paleolithic Diet Clinical Trials
Paleolithic Diet Clinical Trials Part II
One Last Thought
Paleolithic Diet Clinical Trials Part III

Cordain on Saturated Fat

I recently signed up for Dr. Loren Cordain's Paleo Diet newsletter, and I just received my first update. For those of you who aren't familiar with him, Dr. Cordain is a researcher at Colorado State University who studies the effects of hunter-gatherer and modern diets on health. He's made a number of important contributions to our understanding of nutrition and health. He's in my "Nutrition Hall of Fame" on the right sidebar.

His update was about saturated fat. In the past, I've disagreed with Dr. Cordain on this issue, because I thought he felt that saturated fat contributes to the risk of heart attack (although he never described it as a dominant factor). He has recommended trimming the fat off meats and using canola oil rather than just eating the fat. I don't know if I had misunderstood his stance, or if he's had a change of heart, but his current position seems quite reasonable to me. Here are a few brief quotes:

By examining the amounts of saturated fats in pre-agricultural hominin diets, an evolutionary baseline can be established for the normal range and limits of saturated fats that would have conditioned the human genome. While these diets varied due to geography, climate, etc., there is evidence that all hominin species were omnivorous. Thus, dietary saturated fats would have always been present in hominin diets.

There is also evidence that the hominin species that eventually led to Homo began to include more animal food in their diet approximately 2.6 million years ago. Clear evidence shows tool usage to butcher and disarticulate carcasses...

This data suggests that the normal dietary intake of saturated fatty acids that conditioned our species genome likely fell between 10 to 15% of total energy, and that values lower than 10% or higher than 15% would have been the exception.

And the conclusion:

Consequently, population-wide recommendations to lower dietary saturated fats below 10% to reduce the risk of CAD have little or no evolutionary foundation in pre-agricultural Homo sapiens... So we do not need to restrict ourselves to only tuna and turkey breast, avoiding every last gram of saturated fat.

AMEN, brother. I'd like to point out that the average American eats about 11% of his calories as saturated fat (down from 13% in the 1970s), on the low side of what Cordain considers normal for Homo sapiens. This is from the NHANES nutrition surveys.

The effect of a food on an animal's health has everything to do with what that animal is adapted to eating. Feeding a rabbit cholesterol gives it high blood cholesterol and atherosclerosis, but you can't give a dog high cholesterol or atherosclerosis by feeding it cholesterol, unless you kill its thyroid first. Feeding studies in Masai men showed that replacing their fatty, cholesterol-rich milk and blood diet with a cholesterol-free refined diet low in saturated fat caused their total cholesterol and body weight to increase rapidly. Adding purified cholesterol to the cholesterol-free diet did not affect their blood cholesterol concentration. Feeding cholesterol-rich eggs also has a negligible effect on blood cholesterol in most people.

I do still have a slight difference of opinion with Cordain on the saturated fat issue. While I think his numbers for pre-agricultural saturated fat intake are reasonable, his range is probably too narrow. Non-agricultural diets are so variable, I would expect the range to be more like 5 to 30% saturated fat. 5% would represent diets low in fat such as certain Australian Aboriginal diets, and 30% would represent the intake of Northern hunter-gatherers relying heavily on ruminants in fall and winter. During this time, ruminants store most of their fat subcutaneously, and their subcutaneous fat is roughly half saturated. Given that such a wide range of saturated fat intakes are part of our species' ecological niche, it follows that saturated fat is unlikely to be an important determinant of health in the context of an otherwise healthy lifestyle.

Paleopathology at the Origins of Agriculture

In April of 1982, archaeologists from around the globe converged on Plattsburgh, New York for a research symposium. Their goal:

...[to use] data from human skeletal analysis and paleopathology [the study of ancient diseases] to measure the impact on human health of the Neolithic Revolution and antecedent changes in prehistoric hunter-gatherer food economies. The symposium developed out of our perception that many widely debated theories about the origins of agriculture had testable but untested implications concerning human health and nutrition and our belief that recent advances in techniques of skeletal analysis, and the recent explosive increase in data available in this field, permitted valid tests of many of these propositions.

In other words, they got together to see what happened to human health as populations adopted agriculture. They were kind enough to publish the data presented at the symposium in the book Paleopathology at the Origins of Agriculture, edited by the erudite Drs. Mark Nathan Cohen and George J. Armelagos. It appears to be out of print, but luckily I have access to an excellent university library.

There are some major limitations to studying human health by looking at bones. The most obvious is that any soft tissue pathology will have been erased by time. Nevertheless, you can learn a lot from a skeleton. Here are the main health indicators discussed in the book:

• Mortality. Archaeologists are able to judge a person's approximate age at death, and if the number of skeletons is large enough, they can paint a rough picture of the life expectancy and infant mortality of a population.
• General growth. Total height, bone thickness, dental crowding, and pelvic and skull shape are all indicators of relative nutrition and health. This is particularly true in a genetically stable population. Pelvic depth is sensitive to nutrition and determines the size of the birth canal in women.
  
• Episodic stress. Bones and teeth carry markers of temporary "stress", most often due to starvation or malnutrition. Enamel hypoplasia, horizontal bands of thinned enamel on the teeth, is probably the most reliable marker. Harris lines, bands of increased density in long bones that may be caused by temporary growth arrest, are another type.
  
• Porotic hyperostosis and cribra orbitalia. These are both skull deformities that are caused by iron deficiency anemia, and are rather creepy to look at. They're typically caused by malnutrition, but can also result from parasites.
  
• Periosteal reactions. These are bone lesions resulting from infections.
• Physical trauma, such as fractures.
• Degenerative bone conditions, such as arthritis.
• Isotopes and trace elements. These can sometimes yield information about the nutritional status, diet composition and diet quality of populations.
  
• Dental pathology. My favorite! This category includes cavities, periodontal disease, missing teeth, abscesses, tooth wear, and excessive dental plaque.

The book presents data from 19 regions of the globe, representing Africa, Asia, the Middle East, Europe, South America, with a particular focus on North America. I'll kick things off with a fairly representative description of health in the upper Paleolithic in the Eastern Mediterranean. The term "Paleolithic" refers to the period from the invention of stone tools by hominids 2.5 million years ago, to the invention of agriculture roughly 10,000 years ago. The upper Paleolithic lasted from about 40,000 to 10,000 years ago. From page 59:

In Upper Paleolithic times nutritional health was excellent. The evidence consists of extremely tall stature from plentiful calories and protein (and some microevolutionary selection?); maximum skull base height from plentiful protein, vitamin D, and sunlight in early childhood; and very good teeth and large pelvic depth from adequate protein and vitamins in later childhood and adolescence...
Adult longevity, at 35 years for males and 30 years for females, implies fair to good general health...
There is no clear evidence for any endemic disease.

The level of skeletal (including cranial and pelvic) development Paleolithic groups exhibited has remained unmatched throughout the history of agriculture. There may be exceptions but the trend is clear. Cranial capacity was 11% higher in the upper Paleolithic. You can see the pelvic data in this table taken from Paleopathology at the Origins of Agriculture.

There's so much information in this book, the best I can do is quote pieces of the editor's summary and add a few remarks of my own. One of the most interesting things I learned from the book is that the diet of many hunter-gatherer groups changed at the end of the upper Paleolithic, foreshadowing the shift to agriculture. From pages 566-568:

During the upper Paleolithic stage, subsistence seems focused on relatively easily available foods of high nutritional value, such as large herd animals and migratory fish. Some plant foods seem to have been eaten, but they appear not to have been quantitatively important in the diet. Storage of foods appears early in many sequences, even during the Paleolithic, apparently to save seasonal surpluses for consumption during seasons of low productivity.

As hunting and gathering economies evolve during the Mesolithic [period of transition between hunting/gathering and agriculture], subsistence is expanded by exploitation of increasing numbers of species and by increasingly heavy exploitation of the more abundant and productive plant species. The inclusion of significant amounts of plant food in prehistoric diets seems to correlate with increased use of food processing tools, apparently to improve their taste and digestibility. As [Dr. Mark Nathan] Cohen suggests, there is an increasing focus through time on a few starchy plants of high productivity and storability. This process of subsistence intensification occurs even in regions where native agriculture never developed. In California, for example, as hunting-gathering populations grew, subsistence changed from an early pattern of reliance on game and varied plant resources to to one with increasing emphasis on collection of a few species of starchy seeds and nuts.

...As [Dr. Cohen] predicts, evolutionary change in prehistoric subsistence has moved in the direction of higher carrying capacity foods, not toward foods of higher-quality nutrition or greater reliability. Early nonagricultural diets appear to have been high in minerals, protein, vitamins, and trace nutrients, but relatively low in starch. In the development toward agriculture there is a growing emphasis on starchy, highly caloric food of high productivity and storability, changes that are not favorable to nutritional quality but that would have acted to increase carrying capacity, as Cohen's theory suggests.

Why am I getting the feeling that these archaeologists have a better grasp of human nutrition than the average medical doctor or nutritionist? They have the Price-esque understanding that comes from comparing the diets and multi-generational health of diverse human populations.

One of the interesting things I learned from the book is that Mesolithic populations, groups that were halfway between farming and hunting-gathering, were generally as healthy as hunter-gatherers:

...it seems clear that seasonal and periodic physiological stress regularly affected most prehistoric hunting-gathering populations, as evidenced by the presence of enamel hypoplasias and Harris lines. What also seems clear is that severe and chronic stress, with high frequency of hypoplasias, infectious disease lesions, pathologies related to iron-deficiency anemia, and high mortality rates, is not characteristic of these early populations. There is no evidence of frequent, severe malnutrition, so the diet must have been adequate in calories and other nutrients most of the time. During the Mesolithic, the proportion of starch in the diet rose, to judge from the increased occurrence of certain dental diseases [with exceptions to be noted later], but not enough to create an impoverished diet... There is a possible slight tendency for Paleolithic people to be healthier and taller than Mesolithic people, but there is no apparent trend toward increasing physiological stress during the mesolithic.

Cultures that adopted intensive agriculture typically showed a marked decline in health indicators. This is particularly true of dental health, which usually became quite poor.

Stress, however, does not seem to have become common and widespread until after the development of high degrees of sedentism, population density, and reliance on intensive agriculture. At this stage in all regions the incidence of physiological stress increases greatly, and average mortality rates increase appreciably. Most of these agricultural populations have high frequencies of porotic hyperostosis and cribra orbitalia, and there is a substantial increase in the number and severity of enamel hypoplasias and pathologies associated with infectious disease. Stature in many populations appears to have been considerably lower than would be expected if genetically-determined maxima had been reached, which suggests that the growth arrests documented by pathologies were causing stunting... Incidence of carbohydrate-related tooth disease increases, apparently because subsistence by this time is characterized by a heavy emphasis on a few starchy food crops.

Infectious disease increased upon agricultural intensification:

Most [studies] conclude that infection was a more common and more serious problem for farmers than for their hunting and gathering forebears; and most suggest that this resulted from some combination of increasing sedentism, larger population aggregates, and the well-established synergism between infection and malnutrition.

There are some apparent exceptions to the trend of declining health with the adoption of intensive agriculture. In my observation, they fall into two general categories. In the first, health improves upon the transition to agriculture because the hunter-gatherer population was unhealthy to begin with. This is due to living in a marginal environment or eating a diet with a high proportion of wild plant seeds. In the second category, the culture adopted rice. Rice is associated with less of a decline in health, and in some cases an increase in overall health, than other grains such as wheat and corn. In chapter 21 of the book Ancient Health: Bioarchaeological Interpretations of the Human Past, Drs. Michelle T Douglas and Michael Pietrusewsky state that "rice appears to be less cariogenic [cavity-promoting] than other grains such as maize [corn]."

One pathology that seems to have decreased with the adoption of agriculture is arthritis. The authors speculate that it may have more to do with strenuous activity than other aspects of the lifestyle such as diet. Another interpretation is that the hunter-gatherers appeared to have a higher arthritis rate because of their longer lifespans:

The arthritis data are also complicated by the fact that the hunter-gatherers discussed commonly displayed higher average ages at death than did the farming populations from the same region. The hunter-gatherers would therefore be expected to display more arthritis as a function of age even if their workloads were comparable [to farmers].

In any case, it appears arthritis is normal for human beings and not a modern degenerative disease.

And the final word:

Taken as a whole, these indicators fairly clearly suggest an overall decline in the quality-- and probably in the length-- of human life associated with the adoption of agriculture.

How to Eat Grains

Our story begins in East Africa in 1935, with two Bantu tribes called the Kikuyu and the Wakamba. Their traditional diets were mostly vegetarian and consisted of sweet potatoes, corn, beans, plantains, millet, sorghum, wild mushrooms and small amounts of dairy, small animals and insects. Their food was agricultural, high in carbohydrate and low in fat.

Dr. Weston Price found them in good health, with well-formed faces and dental arches, and a dental cavity rate of roughly 6% of teeth. Although not as robust or as resistant to tooth decay as their more carnivorous neighbors, the "diseases of civilization" such as cardiovascular disease and obesity were nevertheless rare among them. South African Bantu eating a similar diet have a low prevalence of atherosclerosis, and a measurable but low incidence of death from coronary heart disease, even in old age.

How do we reconcile this with the archaeological data showing a general decline in human health upon the adoption of agriculture? Humans did not evolve to tolerate the toxins, anti-nutrients and large amounts of fiber in grains and legumes. Our digestive system is designed to handle a high-quality omnivorous diet. By high-quality, I mean one that has a high ratio of calories to indigestible material (fiber). Our species is very good at skimming off the highest quality food in nearly any ecological niche. Animals that are accustomed to high-fiber diets, such as cows and gorillas, have much larger, more robust and more fermentative digestive systems.

One factor that reconciles the Bantu data with the archaeological data is that much of the Kikuyu and Wakamba diet came from non-grain sources. Sweet potatoes and plantains are similar to the starchy wild plants our ancestors have been eating for nearly two million years, since the invention of fire (the time frame is debated but I think everyone agrees it's been a long time). Root vegetables and starchy fruit have a higher nutrient bioavailibility than grains and legumes due to their lower content of anti-nutrients and fiber.

The second factor that's often overlooked is food preparation techniques. These tribes did not eat their grains and legumes haphazardly! This is a factor that was overlooked by Dr. Price himself, but has been emphasized by Sally Fallon. Healthy grain-based African cultures typically soaked, ground and fermented their grains before cooking, creating a sour porridge that's nutritionally superior to unfermented grains. The bran was removed from corn and millet during processing, if possible. Legumes were always soaked prior to cooking.

These traditional food processing techniques have a very important effect on grains and legumes that brings them closer in line with the "paleolithic" foods our bodies are designed to digest. They reduce or eliminate toxins such as lectins and tannins, greatly reduce anti-nutrients such as phytic acid and protease inhibitors, and improve vitamin content and amino acid profile. Fermentation is particularly effective in this regard. One has to wonder how long it took the first agriculturalists to discover fermentation, and whether poor food preparation techniques or the exclusion of animal foods could account for their poor health.

I recently discovered a paper that illustrates these principles: "Influence of Germination and Fermentation on Bioaccessibility of Zinc and Iron from Food Grains". It's published by Indian researchers who wanted to study the nutritional qualities of traditional fermented foods. One of the foods they studied was idli, a South Indian steamed "muffin" made from rice and beans. Idlis happen to be one of my favorite foods.

The amount of minerals your digestive system can extract from a food depends in part on the food's phytic acid content. Phytic acid is a molecule that traps certain minerals (iron, zinc, magnesium, calcium), preventing their absorption. Raw grains and legumes contain a lot of it, meaning you can only absorb a fraction of the minerals present in them.

In this study, soaking had a modest effect on the phytic acid content of the grains and legumes examined (although it's generally more effective). Fermentation, on the other hand, completely broke down the phytic acid in the idli batter, resulting in 71% more bioavailable zinc and 277% more bioavailable iron. It's safe to assume that fermentation also increased the bioavailability of magnesium, calcium and other phytic acid-bound minerals.

Fermenting the idli batter also completely eliminated its tannin content. Tannins are a class of molecules found in many plants that are toxins and anti-nutrients. They reduce feed efficiency and growth rate in a variety of species.

Lectins are another toxin that's frequently mentioned in the paleolithic diet community. They are blamed for everything from digestive problems to autoimmune disease, probably with good reason. One of the things people like to overlook in this community is that traditional processing techniques such as soaking, sprouting, fermentation and cooking, greatly reduce or eliminate lectins from grains and legumes. One notable exception is gluten, which survives all but the longest fermentation and is not broken down by cooking.

Soaking, sprouting, fermenting, grinding and cooking are the techniques by which traditional cultures have been making the most of grain and legume-based diets for thousands of years. We ignore these time-honored traditions at our own peril.

Paleolithic Diet Clinical Trials Part III

I'm happy to say, it's time for a new installment of the "Paleolithic Diet Clinical Trials" series. The latest study was recently published in the European Journal of Clinical Nutrition by Dr. Anthony Sebastian's group. Dr. Sebastian has collaborated with Drs. Loren Cordain and Boyd Eaton in the past.

This new trial has some major problems, but I believe it nevertheless adds to the weight of the evidence on "paleolithic"-type diets. The first problem is the lack of a control group. Participants were compared to themselves, before eating a paleolithic diet and after having eaten it for 10 days. Ideally, the paleolithic group would be compared to another group eating their typical diet during the same time period. This would control for effects due to getting poked and prodded in the hospital, weather, etc. The second major problem is the small sample size, only 9 participants. I suspect the investigators had a hard time finding enough funding to conduct a larger study, since the paleolithic approach is still on the fringe of nutrition science.

I think this study is best viewed as something intermediate between a clinical trial and 9 individual anecdotes.

Here's the study design: they recruited 9 sedentary, non-obese people with no known health problems. They were 6 males and 3 females, and they represented people of African, European and Asian descent. Participants ate their typical diets for three days while investigators collected baseline data. Then, they were put on a seven-day "ramp-up" diet higher in potassium and fiber, to prepare their digestive systems for the final phase. In the "paleolithic" phase, participants ate a diet of:

Meat, fish, poultry, eggs, fruits, vegetables, tree nuts, canola oil, mayonnaise, and honey... We excluded dairy products, legumes, cereals, grains, potatoes and products containing potassium chloride...

Mmm yes, canola oil and mayo were universally relished by hunter-gatherers. They liked to feed their animal fat and organs to the vultures, and slather mayo onto their lean muscle meats. Anyway, the paleo diet was higher in calories, protein and polyunsaturated fat (I assume with a better n-6 : n-3 ratio) than the participants' normal diet. It contained about the same amount of carbohydrate and less saturated fat.

There are a couple of twists to this study that make it more interesting. One is that the diets were completely controlled. The only food participants ate came from the experimental kitchen, so investigators knew the exact calorie intake and nutrient composition of what everyone was eating.

The other twist is that the investigators wanted to take weight loss out of the picture. They wanted to know if a paleolithic-style diet is capable of improving health independent of weight loss. So they adjusted participants' calorie intake to make sure they didn't lose weight. This is an interesting point. Investigators had to increase the participants' calorie intake by an average of 329 calories a day just to get them to maintain their weight on the paleo diet. Their bodies naturally wanted to shed fat on the new diet, so they had to be overfed to maintain weight.

On to the results. Participants, on average, saw large improvements in nearly every meaningful measure of health in just 10 days on the "paleolithic" diet. Remember, these people were supposedly healthy to begin with. Total cholesterol and LDL dropped, if you care about that. Triglycerides decreased by 35%. Fasting insulin plummeted by 68%. HOMA-IR, a measure of insulin resistance, decreased by 72%. Blood pressure decreased and blood vessel distensibility (a measure of vessel elasticity) increased. It's interesting to note that measures of glucose metabolism improved dramatically despite no change in carbohydrate intake. Some of these results were statistically significant, but not all of them. However, the authors note that:

In all these measured variables, either eight or all nine participants had identical directional responses when switched to paleolithic type diet, that is, near consistently improved status of circulatory, carbohydrate and lipid metabolism/physiology.

Translation: everyone improved. That's a very meaningful point, because even if the average improves, in many studies a certain percentage of people get worse. This study adds to the evidence that no matter what your gender or genetic background, a diet roughly consistent with our evolutionary past can bring major health benefits. Here's another way to say it: ditching certain modern foods can be immensely beneficial to health, even in people who already appear healthy. This is true regardless of whether or not one loses weight.

There's one last critical point I'll make about this study. In figure 2, the investigators graphed baseline insulin resistance vs. the change in insulin resistance during the course of the study for each participant. Participants who started with the most insulin resistance saw the largest improvements, while those with little insulin resistance to begin with changed less. There was a linear relationship between baseline IR and the change in IR, with a correlation of R=0.98, p less than 0.0001. In other words, to a highly significant degree, participants who needed the most improvement, saw the most improvement. Every participant with insulin resistance at the beginning of the study ended up with basically normal insulin sensitivity after 10 days. At the end of the study, all participants had a similar degree of insulin sensitivity. This is best illustrated by the standard deviation of the fasting insulin measurement, which decreased 9-fold over the course of the experiment.

Here's what this suggests: different people have different degrees of susceptibility to the damaging effects of the modern Western diet. This depends on genetic background, age, activity level and many other factors. When you remove damaging foods, peoples' metabolisms normalize, and most of the differences in health that were apparent under adverse conditions disappear. I believe our genetic differences apply more to how we react to adverse conditions than how we function optimally. The fundamental workings of our metabolisms are very similar, having been forged mostly in hunter-gatherer times. We're all the same species after all.

This study adds to the evidence that modern industrial food is behind our poor health, and that a return to time-honored foodways can have immense benefits for nearly anyone. A paleolithic-style diet is a very effective way to claim your genetic birthright to good health. Just remember to eat the organs and fat. And skip the canola oil and mayonnaise.

Paleolithic Diet Clinical Trials
Paleolithic Diet Clinical Trials Part II
One Last Thought

One Last Thought

In Dr. Lindeberg's paleolithic diet trial, subjects began with ischemic heart disease, and glucose intolerance or type II diabetes. By the end of the 12-week study, on average their glucose control was approaching normal and every subject had normal fasting glucose. Glucose control and fasting glucose in subjects following the "Mediterranean diet" did not change significantly. He didn't report changes in cardiovascular risk factors.

Why was the paleolithic diet so effective at restoring glucose control, while the Mediterranean diet was not? I believe the reason is that the Mediterranean diet did not eliminate the foods that were causing the problem to begin with: processed grains, particularly wheat. The paleolithic diet was lower in carbohydrate than the Mediterranean diet (40% vs 52%), although not exceptionally so. The absolute difference was larger since the paleolithic dieters were eating fewer calories overall (134 g vs 231 g). When they analyzed the data, they found that "the effect of the paleolithic diet on glucose tolerance was independent of carbohydrate intake". In other words, paleolithic dieters saw an improvement in glucose tolerance even if they ate as much carbohydrate as the average for the Mediterranean group.

This study population is not representative of the general public. These are people who suffered from an extreme version of the "disease of civilization". But they are examples of a process that I believe applies to nearly all of us to some extent. This paper adds to the evidence that the modern diet is behind these diseases.

A quick note about grains. Some of you may have noticed a contradiction in how I bash grains and at the same time praise Nutrition and Physical Degeneration. I'm actually not against grains. I think they can be part of a healthy diet, but they have to be prepared correctly and used in moderation. Healthy non-industrial cultures almost invariably soaked, sprouted or sourdough-fermented their grains. These processes make grains much more nutritious and less irritating to the digestive tract, because they allow the seeds to naturally break down their own toxins such as phytic acid, trypsin inhibitors and lectins.

Gluten grains are a special case. 12% of the US public is though to be gluten sensitive, as judged by anti-gliadin antibodies in the bloodstream. Nearly a third have anti-gliadin antibodies in their feces. Roughly 1% have outright celiac disease, in which the gut lining degenerates in response to gluten. All forms of gluten sensitivity increase the risk of a staggering array of health problems. There's preliminary evidence that gluten may activate the innate immune system in many people even in the absence of antibodies. From an anthropological perspective, wherever wheat flour goes, so does the disease of civilization. Rice doesn't have the same effect. It's possible that properly prepared wheat, such as sourdough, might not cause the same problems, but I'm not taking my chances. I certainly don't recommend quick-rise bread, and that includes whole wheat. Whole wheat seemed to be enough to preserve glucose intolerance in Lindeberg's study...

Paleolithic Diet Clinical Trials Part II

There were a number of remarkable changes in both trials. I'll focus mostly on Dr. Lindeberg's trial because it was longer and better designed. The first thing I noticed is that caloric intake dropped dramatically in both trials, -36% in the first trial and a large but undetermined amount in Dr Lindeberg's. The Mediterranean diet group ended up eating 1,795 calories per day, while the paleolithic dieters ate 1,344. In both studies, participants were allowed to eat as much as they wanted, so those reductions were purely voluntary.

This again agrees with the theory that certain grains (wheat) promote hyperphagia, or excessive eating. It's the same thing you see in low-carbohydrate diet trials, such as this one, which also reduce grain intake. The participants in Lindeberg's study were borderline obese. When you're overweight and your body resets its fat mass set-point due to an improved diet, fatty acids come pouring out of fat tissue and you don't need as many calories to feel satisfied. Your diet is supplemented by generous quantities of lard. Your brain decreases your calorie intake until you approach your new set-point.

That's what I believe happened here. The paleolithic group supplemented their diet with 3.9 kg of their own rump fat over the course of 12 weeks, coming out to 30,000 additional calories, or 357 calories a day. Not quite so spartan when you think about it like that.

The most remarkable thing about Lindeberg's trial was the fact that the 14 people in the paleolithic group, 2 of which had moderately elevated fasting blood glucose and 10 of which had diabetic fasting glucose, all ended up with normal fasting glucose after 12 weeks. That is truly amazing. The mediterranean diet worked also, but only in half as many participants.

If you look at their glucose tolerance by an oral glocose tolerance test (OGTT), the paleolithic diet group improved dramatically. Their rise in blood sugar after the OGTT (fasting BG subtracted out) was 76% less at 2 hours. If you look at the graph, they were basically back to fasting glucose levels at 2 hours, whereas before the trial they had only dropped slightly from the peak at that timepoint. The mediterranean diet group saw no significant improvement in fasting blood glucose or the OGTT. Lindeberg is pretty modest about this finding, but he essentially cured type II diabetes and glucose intolerance in 100% of the paleolithic group.

Fasting insulin, the insulin response to the OGTT and insulin sensitivity improved in the paleolithic diet whereas only insulin sensitivity improved significantly in the Mediterranean diet. Fasting insulin didn't decrease as much as I would have thought, only 16% in the paleolithic group.

Another interesting thing is that the paleolithic group lost more belly fat than the Mediterranean group, as judged by waist circumference. This is the most dangerous type of fat, which is associated with, and contributes to, insulin resistance and the metabolic syndrome. Guess what food belly fat was associated with when they analyzed the data? The strongest association was with grain consumption (probably mostly wheat), and the association remained even after adjusting for carbohydrate intake. In other words, the carbohydrate content of grains does not explain their association with belly fat because "paleo carbs" didn't associate with it. The effect of the paleolithic diet on glucose tolerance was also not related to carbohydrate intake.

So in summary, the "Mediterranean diet" may be healthier than a typical Swedish diet, while a diet loosely modeled after a paleolithic diet kicks both of their butts around the block. My opinion is that it's probably due to eliminating wheat, substantially reducing refined vegetable oils and dumping the processed junk in favor of real, whole foods. Here's a zinger from the end of the paper that sums it up nicely (emphasis mine):

The larger improvement of glucose tolerance in the Paleolithic group was independent of energy intake and macronutrient composition, which suggests that avoiding Western foods is more important than counting calories, fat, carbohydrate or protein. The study adds to the notion that healthy diets based on whole-grain cereals and low-fat dairy products are only the second best choice in the prevention and treatment of type 2 diabetes.

Paleolithic Diet Clinical Trials

If Dr. Ancel Keys (of diet-heart hypothesis fame) had been a proponent of "paleolithic nutrition", we would have numerous large intervention trials by now either confirming or denying its ability to prevent health problems. In this alternate reality, public health would probably be a lot better than it is today. Sadly, we have to settle for our current reality where the paleolithic diet has only been evaluated in two small trials, and medical research spends its (our) money repeatedly conducting failed attempts to link saturated fat to every ill you can think of. But let's at least take a look at what we have.

Both trials were conducted in Sweden. In the first one, lead by Dr. Per Wändell, 14 healthy participants (5 men, 9 women) completed a 3-week dietary intervention in which they were counseled to eat a "paleolithic diet". Calories were not restricted, only food categories were. Participants were told to eat as much as they wanted of fruit, vegetables, fish, lean meats, nuts, flax and canola oil, coffe and tea (without dairy). They were allowed restricted quantities of dried fruit, potatoes (2 medium/day) salted meat and fish, fat meat and honey. They were told not to eat dairy, grain products, canned food, sugar and salt.

After three weeks, the participants had:

• Decreased their caloric intake from 2,478 to 1,584 kcal
• Increased their percentage protein and fat, while decreasing carbohydrate
• Decreased saturated fat, increased dietary cholesterol, decreased sodium intake, increased potassium
  
• Lost 2.3 kg (5 lb)
• Decreased waist circumference, blood pressure and PAI-1

Not bad for a 3-week intervention on healthy subjects. This study suffered from some serious problems, however. #1 is the lack of a control group as a means for comparison. Ouch. #2 is the small study size and resulting lack of statistical power. I consider this one encouraging but by no means conclusive.

The second study was conducted by the author of the Kitava study, Dr. Staffan Lindeberg. The study design was very interesting. He randomly assigned 29 men with ischemic heart disease, plus type II diabetes or glucose intolerance, to either a "Mediterranean diet" or a "paleolithic diet". Neither diet was calorie-restricted. Here's the beauty of the study design: the Mediterranean diet was the control for the paleo diet. The reason that's so great is it completely eliminates the placebo effect. Both groups were told they were being assigned to a healthy diet to try to improve their health. Each group was educated on the health benefits of their diet but not the other one. It would have been nice to see a regular non-intervention control group as well, but this design was adequate to see some differences.

Participants eating the Mediterranean diet were counseled to focus on whole grains, low-fat dairy, potatoes, legumes, vegetables, fruit, fatty fish and vegetable oils rich in monounsaturated fats and alpha-linolenic acid (omega-3). I'm going to go on a little tangent here. This is truly a bizarre concept of what people eat in the Mediterranean region. It's a fantasy invented in the US to justify the mainstream concept of a healthy diet. My father is French and I spent many summers with my family in southern France. They ate white bread, full-fat dairy at every meal, legumes only if they were smothered in fatty pork, sausages and lamb chops. In fact, full-fat dairy wasn't fat enough sometimes. Many of the yogurts and cheeses we ate were made from milk with extra cream added. Want to get a lecture from Grandmere? Try cutting the fat off your pork chop!

The paleolithic group was counseled to eat lean meat, fish, fruit, leafy and cruciferous vegetables, root vegetables (including moderate amounts of potatoes), eggs and nuts. They were told to avoid dairy, grain products, processed food, sugar and beer.

Both groups were bordering on obese at the beginning of the study. All participants had cardiovascular disease and moderate to severe glucose intolerance (i.e. type II diabetes). After 12 weeks, both groups improved on several parameters. That includes fat mass and waist circumference. But the paleolithic diet trumped the Mediterranean diet in many ways:

• Greater fat loss in the the midsection and a trend toward greater weight loss
  
• Greater voluntary reduction in caloric intake (total intake paleo= 1,344 kcal; Med= 1,795)
  
• A remarkable improvement in glucose tolerance that did not occur significantly in the Mediterranean group
• A decrease in fasting glucose
  
• An increase in insulin sensitivity (HOMA-IR)
  

Overall, the paleolithic diet came out looking very good. But I haven't even gotten to the best part yet. At the beginning of the trial, 12 out of the 14 people in the paleo group had elevated fasting glucose. At the end, every single one had normal fasting glucose. In the Mediterranean group, 13 out of 15 began with elevated glucose and 8 out of 15 ended with it. This clearly shows that a paleolithic diet is an excellent way to restore glucose control to a person who still has beta cells in their pancreas.

This post is getting long, so I think I'll save the interpretation for the next post.

Life Expectancy and Growth of Paleolithic vs. Neolithic Humans

If paleolithic people were healthier than us due to their hunter-gatherer lifestyle, why did they have a shorter life expectancy than we do today? I was just reminded by Scott over at Modern Forager about some data on paleolithic (pre-agriculture) vs. neolithic (post-agriculture) life expectancy and growth characteristics. Here's a link to the table, which is derived from an article in the text Paleopathology at the Origins of Agriculture.

The reason the table is so interesting is it allows us to ask the right question. Instead of "why did paleolithic people have a shorter life expectancy than we do today?", we should ask "how did the life expectancy of paleolithic people compare to that of pre-industrial neolithic people?" That's what will allow us to tease the effects of lifestyle apart from the effects of modern medicine.

The data come from age estimates of skeletons from various archaeological sites representing a variety of time periods in the Mediterranean region. Paleolithic skeletons indicated a life expectancy of 35.4 years for men and 30.0 years for women, which includes a high rate of infant mortality. This is consistent with data from the Inuit that I posted a while back (life expectancy excluding infant mortality = 43.5 years). With modest fluctuations, the life expectancy of humans in this Mediterranean region remained similar from paleolithic times until the last century. I suspect the paleolithic people died most often from warfare, accidents and infectious disease, while the neolithic people died mostly from chronic disease, and infectious diseases that evolved along with the domestication of animals (zoonotic diseases). But I'm just speculating based on what I know about modern populations, so you can take that at face value.

The most interesting part of the table is actually not the life expectancy data. It also contains numbers for average stature and pelvic inlet depth. These are both markers of nutritional status during development. Pelvic inlet depth is a measure of the size of the pelvic canal through which a baby would pass during birth. It can be measured in men and women, but obviously its implications for birth only apply to women. As you can see in the table, stature and pelvic inlet depth declined quite a bit with the adoption of agriculture, and still have not reached paleolithic levels to this day.

The idea that a grain-based diet interferes with normal skeletal development isn't new. It's well-accepted in the field of archaeology that the adoption of grains coincided with a shortening of stature, thinner bones and crooked, cavity-ridden teeth. This fact is so well accepted that these sorts of skeletal changes are sometimes used as evidence that grains were adopted in a particular region historically. Weston Price saw similar changes in the populations he studied, as they transitioned from traditional diets to processed-food diets rich in white wheat flour, sweets and other processed foods.

The change in pelvic inlet depth is also very telling. Modern childbirth is so difficult, it makes you wonder why our bodies have evolved to make it so drawn-out and lethal. Without the aid of modern medicine, many of the women who now get C-sections and other birth interventions would not make it. My feeling is that we didn't evolve to make childbirth so lethal. It's more difficult in modern times, at least partially because we have a narrower pelvic inlet than our ancestors. Another thing Weston Price commented on was the relative ease of childbirth in many of the traditional societies he visited. Here's an exerpt from Nutrition and Physical Degeneration:

A similar impressive comment was made to me by Dr. Romig, the superintendent of the government hospital for Eskimos and Indians at Anchorage, Alaska. He stated that in his thirty-six years among the Eskimos, he had never been able to arrive in time to see a normal birth by a primitive Eskimo woman. But conditions have changed materially with the new generation of Eskimo girls, born after their parents began to use foods of modern civilization. Many of them are carried to his hospital after they had been in labor for several days. One Eskimo woman who had married twice, her last husband being a white man, reported to Dr. Romig and myself that she had given birth to twenty-six children and that several of them had been born during the night and that she had not bothered to waken her husband, but had introduced him to the new baby in the morning.

Now that's what I call fertility!