Category Archives: Paleo Theory

Theoretical Support for the Healthfulness of the Paleo Diet

See modern man walking off that cliff?

See modern man walking off that cliff?

Aren’t people healthier now, thanks to the Agricultural and Industrial Revolutions?

As a marker for health, we can look at life span and longevity. Humans started to see dramatic increases in longevity probably around 30,000 years ago, before the revolutions. Nevertheless, Kuipers, Joordens, and Muskiet note that average life expectancy after the start of the Agricultural Revolution 10,000 years ago fell from about 40 to around 20 years.

Other researchers report that average height in the Nile River Valley at the time of the transition fell by 4 inches (10 cm). The Agricultural Revolution allowed for rapid expansion of human populations through more births, but those folks still didn’t live very long. As before the revolution, infections and high infant/child mortality rates were devastating killers, dragging down average life spans. If you survived childhood, you had a shot at hitting 50 or 60.

At the dawn of the Industrial Revolution, life expectancy at birth was only 35–40 years, even in then-sophisticated cultures like Switzerland. Consider Thomas Jefferson, the principal author of the U.S. Declaration of Independence and the third U.S. president, who lived between 1743 and 1826 (he died on July 4, Independence Day). He and his wife Martha had six children; only two survived to adulthood, and only one past the age of 25. Martha died at age 33. This mortality picture was typical for the times.

Since 1800, life expectancy has doubled in industrialized countries, but it’s mostly due to public health measures and economic prosperity. Other than smallpox vaccination, it wasn’t until the mid-20th century that medical care advances contributed in a major way to longevity.

Overview: Conflict Between Our Paleolithic Genes and Modern Life

A number of diseases or conditions may result from the mismatch of our Paleolithic genes and modern lifestyle. If not caused by the mismatch, they’re aggravated by it. These are the so-called “diseases of civilization”:

  • type 2 diabetes
  • high blood pressure
  • overweigh and obesity
  • dental caries (tooth decay or cavities)
  • osteoporosis
  • fertility problems (polycystic ovary syndrome)
  • pregnancy complications (pre-eclampsia, gestational diabetes)
  • some cancers (colon, breast, prostate)
  • heart disease (such as coronary artery disease)
  • major and postpartum depression
  • autism
  • schizophrenia
  • some neurodegenerative diseases (Parkinsons disease, Alzheimer’s disease)
  • constipation
  • hemorrhoids
  • diverticulosis
"I ate well over 70 grams of fiber daily!"

“I ate well over 70 grams of fiber daily!”

Overweight and Obesity

The Paleolithic diet is lower in total carbohydrate calories compared to the standard American diet: 30-35% versus 50-55% of calories. The higher consumption today, especially of highly processed refined carbohydrates, contributes to overweight and obesity, diabetes, gallbladder disease, heart disease, and possibly dementia. Ian Spreadbury hypothesizes that carbohydrate density of modern foods may be the cause of obesity. Refined sugars and grains—types of acellular carbohydrates—are particularly bad offenders. These acellular carbs may alter our gut microorganisms, leading to systemic inflammation and leptin resistance, etc. Our Paleolithic ancestors had little access to acellular carbohydrates. Here’s how Spreadbury explains acellular: “Tubers, fruits, or functional plant parts such as leaves and stems store their carbohydrates in organelles as part of fiber-walled living cells. These are thought to remain largely intact during cooking, which instead mostly breaks cell-to-cell adhesion. This cellular storage appears to mandate a maximum density of around 23% non-fibrous carbohydrate by mass, the bulk of the cellular weight being made up of water. The acellular carbohydrates of flour, sugar, and processed plant-starch products are considerably more dense. Grains themselves are also highly dense, dry stores of starch designed for rapid macroscopic enzymic mobilization during germination. Whereas foods with living cells will have their low carbohydrate density “locked in” until their cell walls are breached by digestive processes, the chyme produced after consumption of acellular flour and sugar-based foods is thus suggested to have a higher carbohydrate concentration than almost anything the microbiota of the upper GI tract from mouth to small bowel would have encountered during our coevolution.” (Reference: “Comparison with ancestral diets suggests dense acellular carbohydrates promote an inflammatory microbiota, and may be the primary dietary cause of leptin resistance and obesity,” in Diabetes, Metabolic Syndrome, and Obesity: Targets and Therapy. 2012; vol 5: 175–189. doi: 10.2147/DMSO.S33473 http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3402009/)

Added sugar provides 17 % of total energy in modern societies, contributing to overweight, obesity, tooth decay, and diabetes. Modern diets provide 15–20% of calories from protein, compared to 25–30% in the Paleolithic diet. To the extent that high protein consumption is satiating, lower consumption may cause over-eating of carbohydrates and fats, then overweight and obesity and all their associated medical conditions.

Heart Disease

I written elsewhere on the blog that the much lower omega-6 to omega-3 fatty acid ratio in the Paleolithic diet. There’s some evidence that today’s high ratio may contribute to systemic inflammation and chronic disease, heart disease in particular. Today’s ratio is quite high due to our consumption of industrial seed oils, such as those derived from soybeans, peanuts, corn, and safflower. And we don’t eat enough cold-water fatty fish, which are major sources of omega-3 fatty acids. Two long-chain polyunsaturated fatty acids, EPA and DHA, are essential fatty acids. That means our bodies cannot make them. We have to get them from diet. DHA and EPA are also cardioprotective omega-3 fatty acids.

High Blood Pressure

Most modern diets have much more sodium and much less potassium than the Paleolithic diet, perhaps contributing to high blood pressure, which in turn contributes to heart attacks, strokes, and possibly premature death. The higher magnesium content of the paleo diet may also help prevent high blood pressure.

Gastrointestinal Problems

We eat much less fiber these days, contributing to constipation, hemorrhoids, and diverticulosis. Some experts believe low fiber consumption adversely effects development of palate bones, jaws, and tooth placement.

Osteoporosis

Our lower vitamin D levels these days may cause osteoporosis (thin fragile bones) and raise the risk of diabetes and cancer. Our prehistoric ancestors spent more time in the sun, allowing their bodies to make vitamin D.

Type 2 Diabetes

Robert Lustig and associates looked at sugar consumption and diabetes rates in 175 countries and found a strong link between sugar and type 2 diabetes. It’s not proof of causation, just suggestive. From the scientific article abstract: “Duration and degree of sugar exposure correlated significantly with diabetes prevalence in a dose-dependent manner, while declines in sugar exposure correlated with significant subsequent declines in diabetes rates independently of other socioeconomic, dietary and obesity prevalence changes. Differences in sugar availability statistically explain variations in diabetes prevalence rates at a population level that are not explained by physical activity, overweight or obesity.” (Reference: Basu S, Yoffe P, Hills N, Lustig RH (2013) The Relationship of Sugar to Population-Level Diabetes Prevalence: An Econometric Analysis of Repeated Cross-Sectional Data. PLoS ONE 8(2): e57873. doi:10.1371/journal.pone.0057873)

A major diet change from Stone Age to modern diets is a reduction in magnesium consumption. This could be one reason type 2 diabetes is a problem today. A 2013 article at Diabetes Care suggests that higher magnesium consumption in modern populations may protect against type 2 diabetes (Reference: http://care.diabetesjournals.org/content/early/2013/09/23/dc13-1397.abstract.html?papetoc).

Dental Problems

Dentist John Sorrentino wrote at his blog in 2012: “The truth is that tooth decay is a relatively new phenomenon. Until the rise of agriculture roughly 10,000 years ago, THERE WAS NO TOOTH DECAY IN HUMANS. Let that sink in for a moment. Humanity is 2,500,000 years old. For the first 2,490,000 years no one ever had a cavity. If we understand that tooth decay started when people started farming instead of hunting and gathering for a living clearly you realize that tooth decay is a disease or mismatch between what you are eating and what your body expects you to eat. If we examine the past as prologue it becomes clear that the path to proper health starts in the mouth and the answers are so simple that not only did a Cave Man do it. They perfected it.” (Reference: http://www.sorrentinodental.com/blog.html?entry=why-teeth-decay-i)

To be fair and balanced, a research report from 2014 found a very high incidence of caries (cavities) in a Stone Age population living in what is now Morocco. The authors attributed the cavities to heavy consumption of acorns, which are rich in carbohydrates and sticky, to boot.

Orthodontist Mike Mew, BDS, MSc, made a presentation at the 2012 Ancestral Health Symposium titled “Craniofacial Dystrophy—Modern Melting Faces.” Dr. Mew says 30% of folks in Western populations have crooked teeth and/or malocclusion, and the mainstream orthodontic community doesn’t know why. But they’ve got expensive treatment for it! Dr. Mew thinks he knows the cause and he shared it at the symposium. The simple cure is “Teeth together. Lips together. Tongue on the roof of your mouth.” And eat hard food that requires lots of chewing, like our ancestors did, ideally in childhood before age 9. Older people also benefit, he says.

NPR (National Public Radio) in February, 2013, ran an article called “Ancient Choppers Were Healthier Than Ours,” by Audrey Carlsen. An excerpt: “Hunter-gatherers had really good teeth,” says Alan Cooper, director of the Australian Centre for Ancient DNA. “[But] as soon as you get to farming populations, you see this massive change. Huge amounts of gum disease. And cavities start cropping up.” And thousands of years later, we’re still waging, and often losing, our war against oral disease. Our changing diets are largely to blame. In a study published in the Nature Genetics, Cooper and his research team looked at calcified plaque on ancient teeth from 34 prehistoric human skeletons. What they found was that as our diets changed over time — shifting from meat, vegetables and nuts to carbohydrates and sugar — so too did the composition of bacteria in our mouths. Not all oral bacteria are bad. In fact, many of these microbes help us by protecting against more dangerous pathogens. (Reference: http://www.npr.org/blogs/health/2013/02/24/172688806/ancient-chompers-were-healthier-than-ours)

Dentist Mark Burhenne wrote the following at Huffington Post – Canada: “It is generally well accepted that tooth decay, in the modern sense, is a relatively new phenomena. Until the rise of agriculture roughly 10,000 years ago, there was nearly no tooth decay in the human race. Cavities became endemic in the 17th century but became an epidemic in the middle of the 20th century (1950). If we understand that tooth decay started when people started farming, rather than hunting and gathering, it’s clear that tooth decay is the result of a mismatch between what we’re eating and what our bodies are expecting us to eat based on how they evolved….The recent changes in our lifestyle create a “mismatch” for the mouth, which evolved under vastly different environments than what our mouths are exposed to these days. Our mouths evolved to be chewing tough meats and fibrous vegetables. Sugar laden fruit was a rare and special treat for our paleolithic ancestors. Now, our diets are filled with heavily processed foods that take hardly any energy to chew — smoothies, coffees, and sodas high in sugar, white bread, and crackers to name just a few.” (Reference: http://www.huffingtonpost.ca/mark-burhenne/paleo-diet-oral-health_b_4041350.html)

Shrinking Brains

Since the end of the Stone Age, human brain size has been shrinking. That’s not good, is it? Anthropologist John Hawks has noted that over the past 20,000 years, the average volume of the human male brain has decreased from 1,500 cubic centimeters to 1,350 cc, losing a chunk the size of a lemon. The female brain has shrunk proportionately. Anthropologists don’t know why. Is it modern nutrition? The experts aren’t sure what it means for our future. As for me, I think the answer is in Mike Judge’s movie, “Idiocracy.”

His brain was bigger than yours

His brain was bigger than yours

Death By Sugar

Sugar-sweetened beverages kill almost 200,000 worldwide annually, according to a Gitanjali Singh, Ph.D., a postdoctoral research fellow at the Harvard School of Public Health. How could that be? Sugar-sweetened beverages contribute to obesity, which in turn leads to diabetes, cardiovascular disease, and some cancers. (Reference: Singh, GM, et al “Mortality due to sugar-sweetened beverage consumption: A global, regional, and national comparative risk assessment,” American Heart Association Epidemiology and Prevention/Nutrition, Physical Activity and Metabolism 2013 Scientific Sessions, Abstract EPI-13-A-879-AHA.) Reducing consumption of sugar-sweetened beverages was one of the major points in the American Heart Association’s 2010 guidelines for reducing heart disease.

Elderly Cognitive Impairment

Diets high in sugar and other carbohydrates raise the risk of elderly cognitive impairment, according to recent research by the Mayo Clinic. Mild cognitive impairment is often a precursor to incurable dementia. (Most authorities think dementia develops more often in people with diabetes, although some studies refute the linkage.) Researchers followed 940 patients with normal baseline cognitive functioning over the course of four years. Diet was assessed via questionnaire. Study participants were ages 70 to 89. As the years passed, 200 of them developed mild cognitive impairment. Compared with those eating the lowest amount of sugar, those eating the most sugar were 1.5 times more likely to develop cognitive impairment. Looking at total carbohydrate consumption, those eating at the highest levels of carbohydrate consumption were almost twice as likely to develop mild cognitive impairment. The scientists note that those eating lower on the carbohydrate continuum were eating more fats and proteins. (Reference: Mayo Clinic website, published October 16, 2012 http://www.mayoclinic.org/news2012-rst/7128.html)

Is a Paleolithic-Style Diet the Healthiest Way to Eat?

Certified paleo-compliant, plus high omega-3 fatty acids

Certified paleo-compliant, plus high omega-3 fatty acids

The jury’s still out on that one! My strong sense is that it’s definitely more healthful than the Standard American Diet. Maybe the traditional Mediterranean diet or DASH diet is even healthier. Don’t hold your breath waiting for the randomized controlled trials that would answer the question definitively.

If the paleo diet is the healthiest, which version is best? That’s a question for another day (or year).

The most healthful diet for you depends on your genetic make-up and any medical conditions you have.

Steve Parker, M.D.

What Does the Paleolithic Diet Look Like?

Vegetables not in season

Vegetables not in season

It’s quite difficult to know exactly what early humans ate 100,000 years ago. Scientists use a variety of methods to investigate, including analysis of patterns of wear on teeth, searches of prehistoric dwellings, and analysis of carbon isotopes in organic matter.

Some of the best-preserved human prehistoric artifacts are found in caves, which protected them from environmental degradation. That’s why the paleo diet is sometimes called the caveman diet.

We have an inkling of what foods were available in specific climates and regions. We have some ideas about tools our ancestors had available to hunt, gather, and process foods. Perhaps most reliably, we have fairly good data on what modern hunter-gatherer groups eat (for those few still in existence) or ate (for those lately extinct or modernized).

The Paleolithic Versus Typical Modern Western Diet

Today we get most of our calories from grains, sugars, domesticated livestock, and dairy products. On the other hand, our pre-agricultural ancestors ate primarily wild game and naturally occurring plant foods. Their carbohydrates would have come from fruits and vegetables rather than cereal grains, diary products, and refined sugars. They ate no junk food, no industrial seed oils, and very few grains and dairy products. Compared to us, they ate more potassium, fiber, protein, and micronutrients, but less sodium and carbohydrate. They ate relatively more omega-3 fatty acids and less omega-6s. Paleo dieters today aim to consume natural whole foods while minimizing simple sugars and refined starches. The paleo community generally is convinced that grains and legumes are harmful, while others disagree. Dairy products are allowed in some versions of paleo, although purists would vote against. Now let’s dig into the details.

Paleo-compliant

Paleo-compliant

The Eaton and Konner Model

S. Boyd Eaton and Melvin Konner in 2010 looked carefully at the diet of pre-industrial hunter-gatherers and proposed a prototypical ancestral diet. Note that actual diet would vary with climate, latitude, altitude, water availability, etc. Eaton and Konner suggest our ancestral diet looked like this:

  • Carbohydrates: 35-40% of daily energy (calories)
  • Protein: 25-30% of daily energy
  • Fat: 20-35% of daily energy
  • Added sugar: 2% of daily energy
  • Fiber: over 70 g/day
  • EPA and DHA*: 0.7-6 g/day
  • Cholesterol: 500+ mg/day
  • Vitamin C: 500 mg/day
  • Vitamin D: 4,000 IU/day (sunlight)
  • Calcium: 1,000-1,500 mg/day
  • Sodium: under 1,000 mg/day
  • Potassium: 7,000 mg/day

*Eicosapentaenoic acid and docosahexaenoic acid (omega-3 fatty acids)

Their conception of a modern Paleolithic food pyramid is a base of high-fiber vegetables and fruits, the next tier up being meat/fish/low-fat dairy (all lean), then a possible tier for whole grain (admittedly very unusual), with a small peak of oils, fats, and refined carbohydrates. Their inclusion of dairy products and whole grains must be a concession to convenience and the reality that those items can be healthful for modern humans. Eaton and Konner note that hunter-gatherer groups had a high degree of dependence on plant foods, while obtaining 35 to 65% of diet (calories rather than weight, I assume) from animal flesh. They found some modern hunter-gatherer cultures deriving as much as 65% of calories from carbohydrate (mostly plants, then). It’s a mistake to assume that the typical Paleolithic diet is necessarily meat-based, as the popular press so often describes it.

Eaton and Konner make a few other distinctions that are worth mentioning now. Game animals have more mono- and polyunsaturated fatty acids than supermarket meat. The Paleolithic diet’s ratio of omega-6 to omega-3 fatty acids was about 2:1, in contrast to the modern Western ratio of 10:1 or even higher.

I’d like to share a few more tidbits from their 2010 article:

  • The transition from hunting/gathering to farming (about 10,000 year ago) saw a decrease in body size and robustness, plus evidence of nutritional stress.
  • Levels of muscular and aerobic fitness in ancestral groups are much higher than modern societies, with a concomittant higher level of calorie consumption.
  • Average life expectancies in pre-industrial hunter-gatherer (H-G) groups was only 30-35 years, but much of this low number simply reflects high infant and child death rates.
  • H-G deaths overwhelmingly reflect infectious diseases.
  • H-G groups had a high degree of dependence on plant foods.
  • Fish and shellfish are more important food sources than these authors thought 25 years earlier.
  • H-G diets are higher in fat and protein than they once thought. • Nearly all H-G carbs are from vegetables and fruits, which have more favorable glycemic responses (i.e., a lesser rise in blood sugar) than grains and concentrated sugars.
  • Uncultivated or wild fruits and vegetables have much more fiber than commercial ones (13 versus 4 g fiber per 100 g of food).

The Diet-Heart Hypothesis is the idea that dietary total and saturated fat, and cholesterol, cause or contribute to atherosclerosis (hardening of the arteries), leading to heart attacks and strokes. Konner and Eaton still believe (in 2010 at least) the theory is valid for fats, but not cholesterol. The latest evidence, however, is that even total and saturated fat are minimally or unrelated to atherosclerosis. They also believe total fat, due to its caloric load, is an important contributor to obesity and type 2 diabetes. I agree that may be true, especially if you eat a lot of carbohydrates with fat. To further imitate the Paleolithic lifestyle, Eaton and Konner also recommend high activity levels, including resistance exercise, flexibility, and aerobics, burning over 1,000 calories daily exclusive of resting metabolism. (Reference: Konner, Melvin and Eaton, S. Boyd. Paleolithic Nutrition: Twenty-Five Years Later. Nutrition in Clinical Practice, 25 (2010): 594-602. doi: 10.1177/0884533610385702) But let’s not put all our eggs in the Eaton and Konner basket.

That exposed skin makes vitamin D

That exposed skin makes vitamin D

The Kuipers Model

A 2010 scientific article by Kuipers et al suggests that the East African Paleolithic diet derived, on average, 25-29% of calories from protein, 30-39% from fat, and 39-40% from carbohydrate. That qualifies as mildly low-carb, and similar to Eaton and Konner’s macronutrient breakdown. Modern Western percentages for protein, fat, and carb are 15%, 33%, and 50%, respectively. Kuipers et al suggest that the evolution of our large brains in East Africa may have been possible by utilization of aquatic resources such as fish, lobster, crab, shrimp, sea urchins, squid, octopus, and amphibians. Rather than savannah, this was a land-water ecosytem. Diets here would have been rich in the omega-3 fatty acids (EPA and DHA) we find in fish oil. Kuipers believes roots and tubers were also part of the Paleolithic diet. (Reference: Kuipers, R., et al (L. Cordain and S. Eaton are co-authors) (2010). Estimated macronutrient and fatty acid intakes from an East African Paleolithic diet British Journal of Nutrition, 1-22 DOI: 10.1017/S0007114510002679)

The Cordain Model

Loren Cordain and associates in 2000 suggested that Paleolithic diets derived about a third—22 to 40%—of calories from carbohydrate, based on modern hunter-gatherer societies. The lower carb consumption compared to Western diets left more room for moderate to high amounts of protein and fat. Dr. Cordain is a co-author with Eaton and Konner on many paleo diet scientific articles, so they don’t have many differences. (Reference: Cordain, L., et al. Plant-animal subsistance ratios and macronutrient energy estimations in worldwide hunter-gatherer diets. American Journal of Clinical Nutrition, 71 (2000): 682-692.)

Dr. Cordain (Ph.D.) is probably the preeminent scientist who advocates the Paleolithic diet. He’s made a few modifications in his model diet over the years. From his website in 2014, the following are the seven pillars of his conception of the modern paleo diet compared to the typical Western diet. The paleo diet is:

  • higher in protein (25-30% of calories versus 15%)
  • lower in carbohydrates and glycemic index via nonstarchy fresh fruits and vegetables
  • higher in fiber
  • moderate to high fat content, especially monounsaturated fats and polyunsaturated fats (particularly omega-3 fatty acids)
  • higher in potassium and lower in sodium
  • higher dietary alkaline load relative to acid load (vegetables and fruit counteract the acid in meat and fish)
  • higher in many vitamins, minerals, antioxidants and plant phytochemicals

(Reference: http://thepaleodiet.com/the-paleo-diet-premise/)

Salmon is a great source of omega-3 fatty acids

Salmon is a great source of omega-3 fatty acids

Carbohydrate Content of the Paleo Diet

Since dietary carbohydrates are major contributors to blood sugar, the carbohydrates in the Paleolithic diet are important. It appears that the average paleo diet derived a little over a third of calories from carbohydrate: that qualifies as low-carb since the average Western diet provides half of calories as carbohydrate. The carbohydrates eaten by Paleolithic man were accompanied by lots of fiber, over four times as much as the average American diet (70+ grams versus 15 grams). The sources of carbohydrate were fruits, vegetables, and roots or tubers, with minimal and seasonal contribution from honey. Fiber is important since high consumption is linked in modern times to lower rates of type 2 diabetes, and fiber also slows and limits the rise in blood sugar after meals. Furthermore, the original Paleolithic carbohydrate sources generally would have been much less calorically dense than modern carbohydrates sources. For instance, one Frosted Strawberry Pop-Tart has the same amount of calories (200) as four cups of fresh strawberry halves, but the Pop-Tart has less than one gram of fiber compared to 12 gm in the raw berries.

We Can’t or Won’t Re-Create a True Paleolithic Diet

Because of our modification of edible plants and animals, it’s impossible for most of us to accurately recreate the diet of our Paleolithic ancestors. The closest you could come would be to live entirely off the land, catching or hunting wild animals and foraging for wild plants. That’s a heck of a lot of work, and wouldn’t sustain more than a tiny fraction of the planet’s current seven billion souls. If we’re going to construct a modern Paleolithic-style diet, now we’ve got some anchoring numbers.

Steve Parker, M.D.

Diet Implications of Human Origins and Migration

African Savanna

African Savanna

Until 10,000 to 12,000 or so years ago, humans and our hominin ancestors obtained food through a combination of hunting and foraging. We hunted small or large game and birds. At some point we learned how to catch fish and shellfish. We searched for and gathered up fruits, berries, leafy plants, nuts, seeds, mussels, clams, honey, eggs, and roots.

Young woman sitting at camp fire, holding fried sausage

 

The range of edible items expanded when we harnessed the power of fire for cooking, which was at least 230,000 years ago and may have been as long as a million years ago.Tools and weapons also expanded our possibilities from the very start of the Paleolithic.

 

Prior to 10,000 years ago, we weren’t farming or raising cattle and dairy cows. Available foods depended on local climatic conditions, soil, and water availability. Climate, in turn, is heavily dependent on latitude (how far away from the equator) and altitude. East Africa at the dawn of humanity is described as savanna: grass-filled plains with scattered patches of forest, and relatively dry. Plants and animals available there would be much different than the colder but wetter Europe 200,000 years ago.

Steve Parker MD, paleo diet, paleobetic

Nubian ibex in Israel

 

Humans in Northern Europe tended to eat more animal-based food and relatively less plant matter than savanna-dwellers, perhaps just because there were fewer edible plants growing in the cold climate. Many plants would have been highly seasonal, just as they are now.

Tribes of humans walked or migrated to nearby micro-climates as one plant went out of season and another came into season. Tribes followed prey animals as they also migrated in search of seasonal food.

Due to technological limitations, we wouldn’t have been able to utilize some potential food sources that required much processing, such as cereal grains and legumes. Since we weren’t yet pastoralists (raising sheep, cattle, etc.), we would have access to milk only if we killed a nursing prey animal. Have you ever tried to milk a wild water buffalo? Not advisable. Ability to digest milk beyond infancy was marginal. Even today, two-thirds of humans lose the ability to digest milk after infancy.

The experts debate actively debate how long we’ve been consuming significant amounts of cereal grains and roots. Canadian researchers working in Africa suggest we’ve enjoyed them for over 100,000 years (see Mercader, Julio, et al. Mozambican grass seed consumption during the Middle Stone Age. Science, December 18, 2009.)

Steve Parker, M.D.

Undisturbed Hunter-Gatherers Don’t Have Near-Sightedness

…according to an article at Nutrition Research. That’s in stark contrast to the developed world. Asian Scientist reports that:

In certain developed parts of East Asia, nearsightedness is skyrocketing, with the prevalence of myopia now at an estimated 80 to 90 percent of the population. In areas of the world where families cannot afford eyeglasses, poor vision from nearsightedness is a serious disability that can affect a person’s ability to learn and work.

Steve Parker MD, paleobetic diet,

Should have spent more time outdoors

The authors of the article at Nutrition Research suggest that the better vision of hunter-gatherers as compared to an agrarian culture is related to greater variety and larger quantities of phytochemicals in the H-G group. Here’s their abstract:

Myopia [near-sightedness] is absent in undisturbed hunter-gatherers but ubiquitous in modern populations. The link between dietary phytochemicals and eye health is well established, although transition away from a wild diet has reduced phytochemical variety. We hypothesized that when larger quantities and greater variety of wild, seasonal phytochemicals are consumed in a food system, there will be a reduced prevalence of degenerative-based eye disease as measured by visual acuity. We compared food systems and visual acuity across isolated Amazonian Kawymeno Waorani hunter-gatherers and neighboring Kichwa subsistence agrarians, using dietary surveys, dietary pattern observation, and Snellen Illiterate E visual acuity examinations. Hunter-gatherers consumed more food species (130 vs. 63) and more wild plants (80 vs. 4) including 76 wild fruits, thereby obtaining larger variety and quantity of phytochemicals than agrarians. Visual acuity was inversely related to age only in agrarians (r = -.846, P < .001). As hypothesized, when stratified by age (<40 and ≥ 40 years), Mann-Whitney U tests revealed that hunter-gatherers maintained high visual acuity throughout life, whereas agrarian visual acuity declined (P values < .001); visual acuity of younger participants was high across the board, however, did not differ between groups (P > .05). This unusual absence of juvenile-onset vision problems may be related to local, organic, whole food diets of subsistence food systems isolated from modern food production. Our results suggest that intake of a wider variety of plant foods supplying necessary phytochemicals for eye health may help maintain visual acuity and prevent degenerative eye conditions as humans age.

Who says low-carb paleo diets are mostly meat?

Certain fruits and vegetables are also linked with lower risk of macular degeneration

In the developed world, kids might prevent near-sightedness by basking in the bright sunlight of outdoors or simply by spending time outdoors. I suspect prevention has a lot to do with using our distant vision for hours instead of looking at a screen two feet away or the interior walls of our homes.

Steve Parker, M.D.

Reference: London, D.D. and Beezhold. A phytochemical-rich diet may explain the absence of age-related decline in visual acuity of Amazonian hunter-gatherers in Ecuador. Nutrition Research 2015 Feb;35(2):107-17. doi: 10.1016/j.nutres.2014.12.007. Epub 2014 Dec 31.

A Brief History of Human Evolution and Migration

paleo diet, Paleolithic diet, hunter-gatherer diet

Huaorani hunter in Ecuador

Evolutionary theory holds that we humans—Homo sapiens—evolved from non-human primates (hominins) in a process that started 2.5 million years ago in Africa. Prominent ancestors include Homo habilis (2.3 million years ago) and Homo erectus (1.8 million years ago).

Homo sapiens eventually hit the scene 200,000 years ago, probably in east Africa, which is considered the cradle of humanity. (All Americans can honestly fill out forms that ask for our race as “African-American.”) The paleoanthropologists tell us we share many genetic traits with long-extinct hominins from two million years ago.

African Diaspora

 

The “Out of Africa” hypothesis to explain the worldwide spread of humans says that Homo sapiens arose in Africa, then began migrating out 50 or 100,000 years ago. A competing “multiregional” hypothesis involves Homo erectus dispersing to many regions throughout Africa, Europe, and Asia, then somehow interbreeding and culminating in Homo sapiens in several regions. Homo erectus may have begun to spread out of Africa as long as 1.4 million years ago. Among the experts, the Out of Africa theory is currently favored over the multiregional hypothesis.

Anyway, starting roughly 100,000 years ago, anatomically modern humans began migrating out of Africa, into the Near East. By 50,000 years ago we were into South Asia, then Australia 40 or 50,000 years ago. We spread to Europe 40,000 years ago. Northeast Asians moved into North America (Alaska) 12 to 30,000 years ago; South America followed. We have evidence of behaviorally modern humans from about 50,000 years ago, if not longer. In other words, in addition to looking like us, they acted like us. At this point, we’ve made it to every spot on Earth that can support life. Not to mention the moon.

As points of reference, the Bronze Age started 5,500 years ago in the Near East and the earliest known writing was 5,000 years ago.

I wonder if God made Adam and Eve 200,000 years ago, and Homo habilis, Homo erectus, and our other hominin “ancestors” are just extinct animals like the dodo bird and dinosaurs. Probably not.

Steve Parker, M.D.

Segmented Sleep: Our Ancestral Pattern?

klkjh

Richard Wrangham estimates hominins tamed fire and started cooking with it 1.8 million years ago

I heard about segmented sleep a couple years ago. The idea is that you sleep for maybe three hours, then get up and putter around for two or three hours, then go back to sleep for another three or four hours.

The easy availability of light after sunset has changed our sleeping patterns only recently, on an evolutionary scale. Before we had electric lights, candles, oil and gas lamps, our only sources of artificial light after sundown were campfires and short-lived torches.

Karen Emslie has an article on segmented sleep at Aeon. A snippet:

Before electric lighting, night was associated with crime and fear – people stayed inside and went early to bed. The time of their first sleep varied with season and social class, but usually commenced a couple of hours after dusk and lasted for three or four hours until, in the middle of the night, people naturally woke up. Prior to electric lighting, wealthier households often had other forms of artificial light – for instance, gas lamps – and in turn went to bed later. Interestingly, Ekirch found less reference to segmented sleep in personal papers from such households.

For those who indulged, however, night-waking was used for activities such as reading, praying and writing, untangling dreams, talking to sleeping partners or making love. As Ekirch points out, after a hard day of labouring, people were often too tired for amorous activities at ‘first’ bedtime (which might strike a chord with many busy people today) but, when they woke in the night, our ancestors were refreshed and ready for action. After various nocturnal activities, people became drowsy again and slipped into their second sleep cycle (also for three or four hours) before rising to a new day. We too can imagine, for example, going to bed at 9pm on a winter night, waking at midnight, reading and chatting until around 2am, then sleeping again until 6am.

Think about this if you have insomnia that wakes you in the middle of the night and you can’t get back to sleep. It may not be a detrimental condition that requires medication or other intervention. Can you really win a fight with a million years of evolution?

RTWT.

Steve Parker, M.D.

Ever Heard of Paleolithic Diet Pioneer Arnold De Vries?

paleo diet, Paleolithic diet, hunter-gatherer diet

Not Arnold Paul De Vries or Don Wiss, but a Huaorani hunter in Ecuador

Don Wiss turned me on to another “modern” paleo diet pioneer, Arnold Paul De Vries, who wrote a 1952 book called Primitive Man and His Food. I even found the book on the Internet a few months ago, perhaps in violation of copyright. I can’t find it now. You can request a digital copy of the book here.

I read his thoughts on the diets of North American Indians before my other duties interrupted me.

Steve Parker, M.D.

Reference (see Comments)

Evolutionary Aspects of Obesity, Insulin Resistance, and Cardiovascular Risk

paleo diet, Paleolithic diet, hunter-gatherer diet

Huaorani hunter in Ecuador

Spreadbury and Samis have a review-type article in Current Cardiovascular Risk Reports. Here’s the abstract:

Cardiovascular disease (CVD) is still virtually absent in those rare populations with minimal Western dietary influence. To date, exercise, altered fats, fibre, anti-oxidants or Mediterranean diet do not appear to overcome the discrepancy in CVD between hunter-gatherer and Western populations. The CVD risk factors of obesity and diabetes are driven by increased caloric intake, with carbohydrates potentially implicated. Paradoxically, non-Westernized diets vary widely in macronutrients, glycemic and insulinemic indices, yet apparently produce no obesity or CVD regardless, even with abundant food. ‘Ancestral’ grain-free whole-food diet may represent the best lifestyle intervention for obesity and CVD. Such diets are composed of the cells of living organisms, while Western grains, flour and sugar are dense, acellular powders. Bacterial inflammation of the small intestine and vagal afferents appears a crucial step in leptin-resistance and obesity. Therefore it may be important that the Western diet resembles a bacterial growth medium.

You may remember Spreadbury’s name from his theory about acellular carbohydrates causing obesity via alterations in gut microorganisms. Spreadbury is with the Gastrointestinal Diseases Research Unit, Queen’s University, Kingston, Ontario, Canada.

You can read the articles for yourself. The following are a few of the authors points I found interesting or want to remember.

Does physical activity explain differences in CVD between Westernized and non-Westernized Peoples? They say “maybe.”

Throughout the article are references to aboriginals like the Hadza, Kitavans, Ache, Shuar, Australian aborigines, and Inuits. I always take comparisons of them to modern Europeans with a grain of salt, because of potential genetic differences between the populations. Moreover, diet and activity levels are only two of myriad cultural differences.

Australian Aborigine in Swamp Darwin

Australian Aborigine in Swamp Darwin

Can dietary changes reduce the incidence of CVD? They say it’s unclear.

Regarding modern paleo diet trials, “All the studies with ad libitum eating [eat all you want] have reported a spontaneous reduction in caloric intake in the order of 15-30%.” (Three references.) “The reduced food intake appeared driven by a satiety increase that was apparently not explicable by energy density, fiber or macronutrient content.” (One reference.)

“In those eating a Westernized diet, carbohydrates are increasingly recognized as being associated with poor metabolic health.” Evidence? Only one reference cited: Zienczuk’s 2012 article on high arctic Inuits.

“…non-Westernized populations with excellent metabolic and cardiovascular health almost invariably have negligible dietary contribution from grains, as well as refined sugar.” No citations.

“For ‘western-style’ diets and most obesogenic diets tested, gut microbiota appear to play a crucial role in obesity.” That’s a bold statement. References? Only one, a mouse study.

The rest of the article is about Spreadbury’s acellular carb/obesity theory. He suggests that small intestine bacteria play a more prominent role than colonic germs. Bacterial-driven inflammation….

The authors provide an example of a grain-free whole-food diet. It’s unrestricted in fruit, leafy or root vegetables, unprocessed meats, eggs, fish, nuts (except peanuts), mushrooms, herbs and spices. Occasional foods to be eaten in moderation are legumes, rice, yogurt, milk, cheeses, sweet corn, palm oil/lard/olive oil, and salt. Avoid almost all processed foods, breads, cereals, cakes/cookies/donuts etc., refined sugars, dried or processed fruits, vegetable/seed oils, and processed meats. They advise a vitamin D supplement. I’m not sure if they came up with this diet on their own, or it’s S. Lindeberg’s outline.

A final quote:

The macronutrient independence of the health from ancestral diet suggests whole foods are more important to health than their macronutrient or other chemical components, and that good health is associated with unprocessed cellular foods. Flour, sugar and processed foods appear to be important drivers of Western metabolic dysfunction, overweight and inflammation, and may prove to have a profound impact on, or even be the initiators of cardiovascular disease.

I’m sure Spreadbury and Samis would agree we need more basic science and clinical research into these issues, involving human test subjects. Maybe I’m prejudiced, but I’m more interested in Asians, Africans, and Europeans than Shuar people.

Steve Parker, M.D.

Reference: Spreadbury, Ian and Samis, Andrew J.S. Evolutionary aspects of obesity, insulin resistance, and cardiovascular risk. Current Cardiovascular Risk Reports, April 2013, vol. 7, issue 2, pp. 136-146.

Another Review Article In Favor Of Paleolithic Eating

It’s in the Annual Review of Plant Biology. The authors promote fruit and vegetable consumption. A snippet from the 2013 article:

Our Paleolithic ancestors were hunter-gatherers, consuming diets rich in lean wild meat or fish, with relatively high consumption of fruits and green leafy vegetables. Our modern diets, in contrast, are high in saturated fats and starches, added sugars with high energy load, and “unnatural fats” such as transfats. Paleolithic diets, in contrast to those of simians and present-day hunter-gatherers, are estimated to have been approximately 75% fruit [that’s news to me; reference is from S. Lindeberg]. In modern US diets, foods unavailable to Paleolithic societies—including dairy products, cereal grains, refined cereal flour, refined sugars, refined vegetable oils, and alcohol—on average make up 70% of total energy consumption. Of this, 50% is in the form of vegetable oils and refined sugars .Americans currently consume less than 60% of the US Department of Agriculture recommendations for vegetables and less than 50% of the recommendations for fruits.

h/t Bill Lagakos

Reference: Annu. Rev. Plant Biol. 2013. 64:19–46. This article’s doi:10.1146/annurev-arplant-050312-120142

The Mellberg Study: Paleo Diet and Obese Postmenopausal Women

Sweden's Flag. Most of the researchers involved with this study are in Sweden

Sweden’s Flag

Swedish researchers compared a Paleolithic-type diet against a lower-fat, higher-carb diet so often recommend in Nordic countries and in the U.S. Test subjects were obese but otherwise healthy older women. The study lasted two years. Dieters could eat as much as they wanted.

They found that the paleo-style dieters lost more weight, lost more abdominal fat, and lowered their trigyceride levels. When measured six months into the study, the paleo dieters had lost 6.5 kg (14 lb) of body fat compared to 2.6 (6 lb) kg in the other group.

Measured at two years out, the paleo dieters had lost 4.6 kg (10 lb) of body fat compared to 2.9 kg (6 lb) in the other group, but this difference wasn’t statistically significant.

The greatest weight loss was clocked at 12 months: Paleo dieters were down 8.7 (19 lb) kg compared to 4.4 kg (10 lb)  in the other group.

But this study was about more than weight loss. The investigators were also interested in cardiometabolic risk factors and overall body composition.

The Set-Up

I don’t know what the researchers told the women to get them interested. Weight loss versus healthier diet versus ?  This could have influenced the type of women who signed up, and their degree of commitment.

A newspaper ad got the attention of 210 women in Sweden; 70 met the inclusion criteria, which included a body mass index 27 or higher and generally good health. Average age was 60. Average BMI was 33. Average weight was 87 kg (192 lb). Average waist circumference was 105 cm (41 inches). The women were randomized into one of two diet groups (N=35 in each): paleolithic-type diet (PD) or Nordic Nutrition Recommendations diet (NNR). There were no limits on total caloric consumption. (Were the women told to “work on weight loss”? I have no idea.)

We don’t know the ethnicity of these women.

Here’s their version of the paleo diet:

  • 30% of energy (calories) from protein
  • 40% of energy from fat
  • 30% of energy from carbohydrate
  • high intake of mono- and polyunsaturated fatty acids
  • based on lean meat, fish, eggs, vegetables, fruits, berries, and nuts
  • additional fat sources were avocado and oils (rapeseed [canola] and olive) used in dressings and food preparation
  • cereals (grains), dairy products, added salt and refined fats and sugar were excluded
  • no mention of legumes, potatoes, or tubers

The NNR diet:

  • 15% of energy from protein
  • 25-30% of energy from fat
  • 55-60% of energy from carbohydrate
  • emphasis on high-fiber products and low-fat dairy products

Over the 24 months of the study, each cohort had 12 group meetings with a dietitian for education and support, including “dietary effects on health, behavioral changes and group discussion.”

Various blood tests and body measurements were made at baseline and periodically. Body measurements were made every six months. Body composition was measured by dual energy x-ray absorptiometry. Diet intake was measured by self-reported periodic four-day food records.

Stockholm Palace

Stockholm Palace

Results

30% of participants (21) eventually dropped out by the end of the study and were lost to follow-up, leaving 27 in the PD group and 22 in the NNR cohort.

Food record analysis indicated the PD group indeed reduced their carb intake while increasing protein and fat over baseline. Baseline macronutrient energy percentages were about the same for both groups: 17% protein, 45% carb, 34% (I guess the percentages don’t add to 100 because of alcohol, which wads not mentioned at all in the article.) Two years out, the PD group’s energy sources were 22% protein, 34% carb, 40% fat. For the NNR group, the energy sources at two years were 17% protein, 43% carb, and 34% fat. As usual, dietary compliance was better at six months compared to 24 months. The PD group failed to reach target amounts of protein energy (30%) at six and 24 months; the NNR group didn’t reach their goal of carbohydrate energy (55-60%). The PD group ate more mono- and poly unsaturated fatty acids than the NNRs.

In contrast to the food record estimates of protein intake, the urine tests for protein indicated poor adherence to the recommended protein consumption in the PD group (30% of energy). Both groups ate the same amount of protein by this metric. (This is an issue mostly ignored by authors, who don’t say which method is usually more accurate.)

“Both groups had statistically significant weight loss during the whole study, with significantly greater weight loos in the PD group at all follow up time points except at 24 months.” Largest weight loss was measured at 12 month: 8.7 kg (19 lb) in the PD group versus 4.4 kg (10 lb) in the NNRs.

The PD group lost 6.5 kg (14 lb) of body fat by six months but the loss was only 4.6 kg (10 lb) measured at 24 months. Corresponding numbers for the NNR group were 2.6 and 2.9 kg (about 6 lb). So both groups decreased their total fat mass to a significant degree. The difference between the groups was significant (P<0.001) only at six months. The greatest weight loss was clocked at 12 months: PD dieters were down 8.7 kg (19 lb) compared to 4.4 kg (10 lb) in the NNRs. Both groups saw a significant decrease in waist circumference during the whole study, with a more pronounce decrease in the PD group at six months: 11 versus 6 cm (4.3 versus 2.4 inches).

Fasting blood sugars, fasting insulin levels, and tissue plasminogen activator activity didn’t change.

Both groups had improvements in blood pressure, heart rate, c-reactive protein, LDL cholesterol, PAI-1 activity, and total cholesterol. The PD group saw a greater drop in triglycerides (by 19% at two years, but levels were normal to start with at 108 mg/dl or 1.22 mmol/l).

Reported daily energy intake fell over time for both groups, without statistically significant differences between them.

paleo diet, Steve Parker MD, diabetic diet

Sweet potato chunks brushed with olive oil, salt, pepper, and rosemary. Ready for the oven.

Discussion

As measured at six months, the paleo dieters lost 10% of their initial body weight, compared to 5% in the NNR group. That’s worth something to many folks. However, the researchers didn’t find much, if any, difference in the groups in terms of cardiometabolic risk factors. They wonder if that reflects the baseline healthiness of these women. Would a sicker study population show more improvement on one of the diets?

I’m surprised the NNR group lost any weight at all. In my experience it’s hard for most folks to lose weight and keep it off while eating as much as they want, unless they’re eating very-low-carb. We’ve seen short-term weight loss with ad libitum paleo diets before (here for example, and here, and here). I bet the women signing up for this study were highly motivated to change. 

Legumes and potatoes are a debatable part of the paleo diet. Most versions exclude legumes. We don’t know if these women ate legumes and potatoes. Other than this oversight, the study paleo diet is reasonable.

The authors noted that the paleo diet group failed to reach their protein intake goal (30% of total calories), and suggested reasons “such as protein-rich foods being more expensive, social influences on women’s food choices or a lower food preference for protein-rich food among women.”

The results of this study may or may not apply to other population subgroups and non-Swedes.

The authors write:

In conclusion, a Palaeolithic-type diet during two years with ad libitum intake of macronutrients, including an increased intake of polyunsaturated fatty acids and monounsaturated fatty acids reduces fat mass and abdominal obesity with significantly better long-term effect on triglyceride levels vs an NNR diet. Adherence to the prescribed protein intake was poor in the PD group suggesting that other component of the PD diet are of greater importance.

Does this study have anything to do with diabetes? Not directly. But it suggests that if an overweight diabetic needs to lose excess body fat without strict calorie control, a lower-carb paleo-style diet may be more effective than a low-fat, higher-carb diet. I would have liked to have seen lower fasting blood sugar and insulin levels in the paleo dieters, but wishing doesn’t make it so.

Steve Parker, M.D.

PS: Carbsane Evelyn has taken a look at this study and blogged about it here and here. I’ve not read those yet, but will now.

Reference: Mellberg, C., et al (including M. Ryberg and T Olsson). Long-term effects of a Palaeolithic-type diet in obese postmenopausal women: a 2-year randomized trial. European Journal of Clinical Nutrition, advance online publication January 29, 2014. doi: 10.1038/ejcn.2013.290