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

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.


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:

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:

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:

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:

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

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.

4 responses to “Theoretical Support for the Healthfulness of the Paleo Diet

  1. Best summing up of paleo diet advantages to date. Thanks so much.

  2. Pingback: Paleo Diabetic – Is a Stone Age diet healthy for diabetics? | Tessa Can Do IT!

  3. Well, estimates, or should I say guestimates, of what was eaten more than 10,000 years ago are truly difficult. As a T1, I know that with food labels and tables showing the average macronutrients of food, I can guess how many carbs I consume by +/- 20%.

    So, to say that the Paleolithic diet included 25 to 30% protein is a guess not a fact. My understanding is that trying to get modern people to eat more than 20% protein can be difficult. Thus, some will do that but many won’t. So, maybe a few would eat 25% protein without some encouragement but I’m guessing most would not, let alone 30%. To be thorough Paleolithic people may not have had much choice of what to eat so would have been forced to eat a lot of protein. BTW, at what level of protein does rabbit poisoning begin?

    An Israeli anthropologist (I don’t remember his name) published a paper concluding that the Paleolithic diet included way more fat than is currently assumed. The main idea was that Paleolithic hunters most often had a choice of which animal to hunt. They would, in this theory, chose to hunt the fattest animal. Fortunately for the caveman, older animals usually have more fat than their younger relatives.

    • Nate, I don’t know the level of protein intake that results in “rabbit poisoning.” I bet it’s quite a bit higher than 30% of calories. Perhaps in the 50-70% range.