Nutrition Science News: April 1997
Paleolithic Nutrition: Your Future Is In Your Dietary Past

Human genes, formed by millions of years of evolution, are a bad match for highly processed modern diets

By Jack Challem

You are what you eat, and perhaps surprisingly, you also are what your ancestors ate. Just as individual genetics and experiences influence your nutritional requirements, millions of years of evolution have also shaped your need for specific nutrients.

The implications? Your genes, which control every function of your body, are essentially the same as those of your early ancestors. Feed these genes well, and they do their job--keeping you healthy. Give these genes nutrients that are unfamiliar or in the wrong ratios and they go awry--aging faster, malfunctioning and leading to disease.

According to S. Boyd Eaton, M.D., one of the foremost authorities on paleolithic (prehistoric) diets and a radiologist and medical anthropologist at Emory University in Atlanta, modern diets are out of sync with our genetic requirements. He makes the point that the less you eat like your ancestors, the more susceptible you'll be to coronary heart disease, cancer, diabetes and many other "diseases of civilization."1 To chart the right direction for improving your current or future nutrition, you have to understand--and often adopt-- the diet of the past.

It helps to go back to the very beginning. Denham Harman, M.D., Ph.D., who conceived the free-radical theory of aging, also theorized that free radicals were a major player in the origin and evolution of life on Earth. According to Harman, professor emeritus of the University of Nebraska, Omaha, free radicals most likely triggered the chemical reactions that led to the first and simplest forms of life some 3.5 billion years ago. But because free-radical oxidation can be destructive, antioxidant defences - including vitamins--likely developed soon after and ensured the survival of life.2

In fact, the first building blocks of life may have been created when solar radiation oxidized compounds in the primordial oceans to produce pantetheine, a form of the B-vitamin pantothenic acid, according to chemist Stanley L. Miller, Ph.D., of the University of California, San Diego.3 Pantetheine is the cornerstone of coenzyme A-- a molecule that helps amino acids link together and makes possible the creation of deoxyribonucleic acid (DNA) and ribonucleic acid (RNA), the building blocks of our genes.

Over the next several billion years, many more molecules--amino acids, lipids, vitamins and minerals--formed and helped construct the countless forms of life. In turn, these life forms became dependent on essentially the same group of nutrients.

According to Eaton, 99 percent of our genetic heritage dates from before our biologic ancestors evolved into Homo sapiens about 40,000 years ago, and 99.99 percent of our genes were formed before the development of agriculture about 10,000 years ago.

Today's Diet,Yesterday's Genes
What we are--and were--can be deduced from paleontological data (mostly ancient bones and coprolites--ancient feces) and the observed habits of hunter-gatherer tribes that survived into the 20th century, according to Eaton.

Before the advent of agriculture about 10,000 years ago, all people were hunter-gatherers; they gathered various fruits and vegetables to eat and they hunted animals for their meat. Of course, the ratio of meat and vegetables varied with geographic location, climate and season. Until they began cultivating grains and livestock, people rarely, if ever, ate grains or drank animal's milk.

With the spread of agriculture, people shifted from nomadic groups to relatively stable and larger societies to tend the fields. Culture and knowledge flourished. People also began consuming large amounts of grain, milk and domesticated meat. When communities became more localized, humans became more sedentary as well. Then, with the industrial revolution of the 18th century, the human diet changed even more dramatically. Beginning around 1900, whole grains were routinely refined, removing much of their nutritional value, and refined sugar became commonplace. Reflecting on the changes in 1939, nutritionist Jean Bogert noted, "The machine age has had the effect of forcing upon the peoples of the industrial nations (especially the United States) the most gigantic human feeding experiment ever attempted."4

Bogert was also disturbed by the growing use of refined grains and sugar and the preference for processed foods over fresh fruits and vegetables. During the past 40 years, the growth of fast-food restaurants has altered the average diet more dramatically than Bogert could have imagined. People now rely even more on processed rather than fresh foods. In fact, the many dietary changes during the past 10,000 years have outpaced our ability to genetically adapt to them, according to Eaton. "That the vast majority of our genes are ancient in origin means that nearly all of our biochemistry and physiology are fine-tuned to conditions of life that existed before 10,000 years ago," he says.5 Looked at in another way, 100,000 generations of people were hunter-gatherers, 500 generations have depended on agriculture, only 10 generations have lived since the start of the industrial age, and only two generations have grown up with highly processed fast foods.

"The problem is that our genes don't know it," Eaton points out. "They are programming us today in much the same way they have been programming humans for at least 40,000 years. Genetically, our bodies now are virtually the same as they were then."6

The Paleolithic Diet
By working with anthropologists, Eaton has created what many experts consider a clear picture of our prehistoric diet and lifestyle. Today's panoply of diets--from fast-food burgers to various concepts of balanced diets and food groups--bears little resemblance, superficially or in actual nutritional constituents, to the diet earliest H. sapiens and their descendants consumed over millions of years. For example, vitamin intake is lower today, and the dietary fatty acid profile is substantially different from our evolutionary diet. In other words, our diet today fails to provide the biochemical and molecular requirements of H. sapiens.7

Here's how the major dietary constituents stack up past and present.

Carbohydrates: Early humans obtained about half of their calories from carbohydrates, but these carbohydrates were rarely grains. Most carbohydrates came from vegetables and fruit.

"Current carbohydrates often take the form of sugars and sweeteners. ... Products of this sort, together with items made from highly refined grain flours, constitute empty calories ... devoid of accompanying essential amino and fatty acids, vitamins, minerals and possibly phytochemicals," Eaton says.8

Fruits, vegetables and fiber: Over the course of one year, hunter- gatherers typically consumed more than 100 different species of fruits and vegetables. Today, fewer than 9 percent of Americans eat the recommended five daily servings of fruits and vegetables, according to Gladys Block, Ph.D., a nutritional epidemiologist at the University of California, Berkeley. Even people who regularly do eat fruits and vegetables generally limit themselves to a handful of different foods, she says.9 The fruits, vegetables, nuts and seeds of H. sapiens provided more than 100 g of fiber daily, far above the typical recommendation of 20 g to 30 g, and even farther above what the average American actually eats. Additionally, Eaton says, "The fiber in preagricultural diets came almost exclusively from fruits, roots, legumes, nuts and other naturally occurring noncereal plant sources, so it was less associated with phytic acid than is fiber from cereal grains [phytic acid interferes with mineral absorption]."

Protein and fat: Early humans consumed about 30 percent protein, although consumption varied with the season and geographic location. Current dietary recommendations suggest much less protein--about 12 percent to 15 percent of total caloric intake. Much of this protein came from what people now call "game meat"--undomesticated animals such as deer and bison.10

Based on contemporary studies of hunter-gatherer societies, it appears early humans consumed relatively large amounts of cholesterol (480 mg daily), but it is extrapolated that their blood cholesterol levels were much lower than those of the average American (about 125 mg vs. 200+ mg per decilitre of blood). There are a couple of reasons for this.

First, domesticating animals increases their saturated fat levels and alters the ratio of omega-6 to omega-3 fatty acids. Saturated fat is associated with increased blood cholesterol levels. Most Americans consume an 11:1 ratio of omega-6 to omega-3 fatty acids. But a more ideal ratio, based on evolutionary and anthropological data, would be in the range of 1:1 to 4:1. In other words, our ancestors consumed a higher percentage of omega-3 fatty acids--and we probably should, too.

Second, hunting and gathering required considerable physical effort, which means early humans exercised a lot, burned fat and lowered cholesterol levels. "Their nomadic foraging lifestyle required vigorous physical exertion, and skeletal remains indicate that they were typically more muscular than we are today," says Eaton. "Life during the agricultural period was also strenuous, but industrialization has progressively reduced obligatory physical exertion."11

Vitamins and minerals: Game meats and wild plant foods contain higher amounts of vitamins and minerals relative to their protein and carbohydrates. Observes Eaton: "The fruits, nuts, legumes, roots and other noncereals that provided 65 percent to 70 percent of typical hunter-gatherer subsistence were generally consumed within hours of being gathered, with little or no processing and often uncooked ... it seems inescapable that preagrarian humans would generally have had an intake of more vitamins and minerals and exceeded currently recommended dietary allowances."12

The difference in consumption of sodium and potassium--electrolyte minerals necessary for normal heart function--is especially dramatic. According to Eaton, the typical adult American consumes about 4,000 mg of sodium daily, but less than 10 percent of this amount occurs naturally in food. The rest is added during processing, cooking or seasoning at the table. Potassium consumption is lower, about 3,000 mg daily.

In contrast, early humans consumed only an estimated 600 mg of sodium but 7,000 mg of potassium daily. People, says Eaton, are the "only free-living terrestrial mammals whose electrolyte intake exhibits this relationship."13 That reversed ratio could be one reason why people are so prone to hypertension and other heart ailments.

Although dietary vitamin and mineral levels in the past were 1.5 to 5 times higher than today, Eaton does not favour"megadoses" of vitamins. However, there is evolutionary evidence that large doses of vitamin C may be needed for optimal health. The reason has less to do with diet and more to do with an evolutionary accident.

Vitamin C And Human Evolution
Evolution often zigzags rather than following a linear flow. One reason is that a species might wipe out another by eating it. In addition, climatic and, more recently, industrial changes, also destroy species. According to the theory of "punctuated equilibrium," proposed by Niles Eldredge, Ph.D., and Stephen Jay Gould, Ph.D., of Harvard University, catastrophic events--such as an asteroid striking the Earth--can also dramatically shift the course of evolution.14

One such catastrophic event of an unknown nature affected the preprimate ancestors of humans sometime between 25 and 70 million years ago, according to biochemist Irwin Stone, Ph.D. This particular event led to a mutation that prevented all of this species' descendants from manufacturing their own vitamin C. At least some of the species were able to survive and evolved into H. sapiens because they lived in a lush equatorial region with vitamin C-rich foods. But nearly all other species of animals, from insects to mammals, continued to produce their own vitamin C.

This theory regarding how our evolutionary ancestors lost their ability to produce vitamin C is generally accepted by scientists, Stone's other theory is more controversial: He contends that people never lost the need for large amounts of vitamin C, even though they lost the ability to make it. Based on animal data, he estimates that people might require 1.8 g - 13 g of vitamin C daily.15 This idea that people require large amounts of vitamin C later became a cornerstone of Nobel laureate Linus Pauling's recommendations for vitamin C in the treatment of colds and cancer. Ironically, losing the ability to produce vitamin C actually may have accelerated the evolution of primates into modern human beings, according to a new theory. Vitamin C is an important antioxidant, and losing the ability to produce it would have allowed the formation of a large number of free radicals. These excessive free radicals would have caused large numbers of DNA mutations, contributing to the aging process and diseases. Some of these mutations would also have been inherited by offspring, creating many biological variations--one of which eventually become H. sapiens.16

A Diet For The Future
For much of history, human life span was not particularly long. Two thousand years ago, the average life expectancy was a mere 22 years, and infections and traumatic injury were the principal causes of death. Better hygiene and sanitation have largely accounted for the dramatic improvement in life expectancy in the 20th century.

Now, as people live longer, they are increasingly susceptible to greater amounts of free-radical damage and their principal end points- -cardiovascular disease and cancer.

The question is: Where do we and our diets go from here? Our evolutionary diet provides important clues to the "baseline" levels and ratios of nutrients needed for health. The evidence suggests we should be eating a lot of plant foods and modest amounts of game meat, but few grains and no dairy products. With a clear understanding of this diet, we have an opportunity to adopt a better, more natural diet. We can also do a better job of individualizing and optimising our nutritional requirements.

Based on our evolutionary and paleolithic diets, it's clear that modern diets are on the wrong track--and that our diets are not satisfying our genetic requirements. In 1939, the same year when Bogert bemoaned the rise of highly refined foods, Nobel laureate Albert Szent-Gyorgyi, M.D., Ph.D., explored the importance of optimal (and not just minimal) requirements of vitamins. Years later, Roger Williams, Ph.D., and Linus Pauling, Ph.D., would also promote the concept of optimal nutrition, based on providing ideal levels of vitamins and other nutrients on a molecular level. Pauling eloquently observed that health depended on the presence of nutritional molecules. To set a dietary course for the future, we have to recognize how certain molecules shaped our lives over millions of years. Paleolithic diets provide those clues and give us a sound foundation to build on, perhaps to protect and prime our genes even further.

A note to those who don't believe in evolution: It's worth observing that evolution describes the mechanism of how life develops, but says nothing about whether a higher being was guiding the process. Regardless, the diet of today is very different from, and not always as good as, the diet of the past.

Jack Challem is based in Aloha, Ore., and has been writing for health magazines for 20 years. He also publishes his own newsletter, The Nutrition Reporter, which summarizes recent medical journal articles on vitamins.

REFERENCES
1. Eaton, S.B., Eaton III, S.B., et al. "An evolutionary perspective enhances understanding of human nutritional requirements," J of Nutr, 126:1732-40, June 1996.

2. Harman, D. "Aging: Prospects for further increases in the functional life span," Age, 17:119-46, 1994.

3. Keefe, A.D., Newton, G.L., et al. "A possible prebiotic synthesis of pantetheine, a precursor to coenzyme A," Nature, 373:683-85, Feb. 23, 1995.

4. Bogert, L.J. Nutrition and Physical Fitness: 437. New York: Saunders, 1939.

5. Eaton, S.B., Shostak, M., et al. The Paleolithic Prescription: A Program of Diet & Exercise and a Design for Living: 39. New York: Harper & Row, 1988.

6. Eaton, Shostak, et al., op cit, 1988:41.

7. Eaton, Shostak, et al., op cit, 1996.

8. Eaton, Shostak, et al., op cit, 1996.

9. Patterson, B.H., Block, G., et al. "Fruit and vegetables in the American diet: Data from the NHANES II survey," Amer J Public Health, 80:1443-49, December 1990.

10. Eaton, S.B., & Konner, M. "Paleolithic nutrition: A consideration of its nature and current implications," N Engl J of Med, 312:283-89, Jan. 31, 1983.

11. Eaton & Konner, op cit, 1996.

12. Eaton & Konner, op cit, 1996.

13. Eaton & Konner, op cit, 1996.

14. Eldredge, N. & Gould, S.J. "Punctuated equilibria: An alternative to phyletic gradualism," Schopf, T.J.M., editor, Models in Paleobiology, San Francisco: Freeman Cooper, 1972.

15. Stone, I. "Hypoascorbemia: The genetic disease causing the human requirement for exogenous ascorbic acid," Perspectives in Biol and Med, 10:133-34, 1966.

16. Challem, J.J. "Did the loss of endogenous ascorbate propel the evolution of anthropoidea and homo sapiens?" Med Hypotheses, in press.