An Interview with Loren Cordain, PhD "E-mail to a friend"
by Dr. Robert Crayhon, MS
Reprinted by permission from Life Services
Can fifty thousand years of human evolution be wrong? What are we really "designed" to eat? Are high carbohydrate "Food Pyramid" diet standards a health disaster? What do paleolithic fossil records and ethnographic studies of 180 hunter/gatherer groups around the world suggest as the ideal human diet? Find out in nationally acclaimed author and nutritionist Dr Robert Crayhon's interview with paleolithic diet expert, Professor Loren Cordain, Ph.D.
Robert Crayhon, M.S. is a clinician, researcher and educator who was called "one of the top ten nutritionists in the country" by Self magazine (August 1993). An associate editor of Total Health magazine, he is the author of best-seller Robert Crayhon's Nutrition Made Simple and the just published The Carnitine Miracle (M. Evans and Company).
Dr. Loren Cordain is a professor of exercise physiology at Colorado State University in Ft. Collins, Colorado, and is a renowned expert in the area of Paleolithic nutrition.
Robert Crayhon: I'm very happy to welcome Dr. Loren Cordain. He is a professor of exercise physiology at Colorado State University in Ft. Collins, Colorado, and an expert in the area of Paleolithic nutrition. Dr. Cordain, welcome.
Loren Cordain: My pleasure to be here.
Robert Crayhon: There has been in the past 40 years or so much interest in the area of low fat diets, and it seems that the media and USDA with its food guide pyramid is now convinced that a healthy diet is one that is predominantly carbohydrate, low in fat and protein. There is also little regard for the quality of the fat or protein.
But are we really just in some great agricultural experiment? Has the last 10,000 years of agriculture really been the bulk of what the human nutritional experience has been? And is this grain-based, high carbohydrate diet truly ideal for humans?
Loren Cordain: There is increasing evidence to indicate that the type of diet recommended in the USDA's food pyramid is discordant with the type of diet humans evolved with over eons of evolutionary experience. Additionally, it is increasingly being recognized that the "food Pyramid" may have a number of serious nutritional omissions.
For instance, it does not specify which types of fats should be consumed. The western diet is overburdened not only by saturated fats, but there is an imbalance in the type of polyunsaturated fats we eat.
We consume too many Omega-6 fats and not enough Omega-3 fats.
The Omega-6/Omega-3 ratio in western diets averages about 12:1.
Whereas data from our recent publication (Eaton SB, Eaton SB 3rd, Sinclair AJ, Cordain L, Mann NJ Dietary intake of long-chain polyunsaturated fatty acids during the Paleolithic Period. World Rev Nutr Diet 1998; 12-23) suggests that:
For most of humanity's existence, prior to agriculture, the Omega-6/Omega-3 ratio would have ranged from 1:1 to 3:1. High dietary Omega-6/Omega-3 ratios are associated with increased risk for cardiovascular disease, some types of cancer, and tend to exacerbate many inflammatory disease responses.
Further, the USDA food pyramid places breads, cereals, rice and pasta at its base and recommends that we consume 6-11 servings of these items daily. Nutritionists at the Harvard School of Public Health (Willett WC. The dietary pyramid: does the foundation need repair? Am J Clin Nutr. 1998;68: 218-219) have recently publicly criticized this recommendation.
It fails to distinguish between refined and complex carbohydrates and their relative glycemic responses. Dr. Willett further pointed out that there was little empirical evidence to support the dominant nutritional message that diets high in complex carbohydrate promote good health.
Both the fossil record and ethnological studies of hunter-gatherers (the closest surrogates we have to stone age humans) indicate that humans rarely if ever ate cereal grains nor did they eat diets high in carbohydrates.
Because cereal grains are virtually indigestible by the human gastrointestinal tract without milling (grinding) and cooking, the appearance of grinding stones in the fossil record generally heralds the inclusion of grains in the diet.
The first appearance of milling stones was in the Middle East roughly 10-15,000 years ago.
These early milling stones were likely used to grind wild wheat which grew naturally in certain areas of the Middle East. Wheat was first domesticated in the Middle East about 10,000 years ago and slowly spread to Europe by about 5,000 years ago. Rice was domesticated approximately 7,000 years ago in SE Asia, India and China, and maize (corn) was domesticated in Mexico and Central America roughly 7,000 years ago. Consequently, diets high in carbohydrate derived from cereal grains were not part of the human evolutionary experience until only quite recent times.
Because the human genome has changed relatively little in the past 40,000 years since the appearance of behaviourally modern humans, our nutritional requirements remain almost identical to those requirements which were originally selected for stone age humans living before the advent of agriculture.
Robert Crayhon: What happened to our health when we switched from a hunter-gatherer diet to a grain-based one?
Loren Cordain: The fossil record indicates that early farmers, compared to their hunter-gatherer predecessors had a characteristic reduction in stature, an increase in infant mortality, a reduction in life span, an increased incidence of infectious diseases, an increase in iron deficiency anaemia, an increased incidence of osteomalacia, porotic hyperostosis and other bone mineral disorders and an increase in the number of dental caries and enamel defects. Early agriculture did not bring about increases in health, but rather the opposite. It has only been in the past 100 years or so with the advent of high tech, mechanized farming and animal husbandry that the trend has changed.
Robert Crayhon: Did we move from a hunter-gatherer lifestyle by choice, or were we forced into the shift due to animal extinction?
Loren Cordain: If we examine the fossil record, it suggests that a number of environmental pressures may have forced humans to adopt agriculture, including increases in human population densities and the depletion of easily hunted game. The extinction of large mammals all over Northern Europe, Asia, and North America coincide with the adoption of agriculture. It is quite likely that pre-agricultural man had sufficient knowledge of his environment to know the life cycle of plants, to be able to sow seeds and grow plants. However, ecologically, it was not necessary, nor energetically efficient to do so when human population numbers were low and game was plentiful. Although agriculture is a vast science and can encompass numerous disciplines, early agriculture essentially involved the domestication, growing and harvesting of cereal grains.
Robert Crayhon: Is there enough evidence to suggest that a diet that includes a large amount of grains is a step down nutritionally, and one that is far from optimal for humans? And how much of the prehistoric diet was animal, and how much was vegetable?
Loren Cordain: The fossil evidence as well as the ethnographic evidence from groups of hunter-gatherers studied in historical times suggests that the diet of pre-agricultural humans was derived primarily from animal based foods. It is difficult to quantitatively determine from the fossil record the proportion of plant to animal food that was included in the diet of prehistoric humans. However, we do know that hunting of game was an important part of all pre-agricultural societies. Most prehistoric humans followed large game herds, and manufactured tools and weapons which were used to regularly kill and butcher these animals.
Ethnographic studies of living hunter-gatherer societies represent the best surrogate we have for estimating quantitatively the plant to animal subsistence ratios of stone-age humans. We have recently compiled ethnographic data from 181 worldwide societies of hunter-gatherers showing that the mean plant to animal subsistence ratio in terms of energy was 35% plant and 65% animal.
Thus, the fossil and ethnographic data suggests that humans evolved on a diet that was primarily animal based and consequently low to moderate in carbohydrate, high in protein and low to moderate in fat. This is in contrast to the low fat, high carbohydrate, plant based diet which is almost universally recommended by modern day nutritionists.
Clearly, humans can adapt to many types of diets involving multiple macronutrient combinations with varying amounts of fat, protein and carbohydrate. However, our genetic constitutions, including our nutritional requirements were established in the remote past over eons of evolutionary experience.
Human health and well being can be optimized when we use the evolutionary paradigm as the starting point for present day nutrition.
Obviously, humans have had little evolutionary experience with the modern high carbohydrate, high fat, cereal based diet which is omnipresent in western, industrialized countries, and there is considerable evidence to suggest that these types of diets have the potential for creating health problems in some, but not all people.
Robert Crayhon: How much cereal grain is too much?
Loren Cordain: That varies by the person. Some people can handle more cereal grains than others. For a celiac patient a single teaspoonful of gluten containing grains is too much.
Generally, health begins to noticeably be disrupted when cereal grains provide 70% or more of the daily caloric intake. The human dietary staple for more than 2 million years was lean game meat supplemented by fresh fruits and vegetables. Including lean meats (seafood, fish, game meat-if you can get it, lean cuts of poultry & domestic meat) more fruits, vegetables at the expense of cereal grains is a good starting point for improving nutrition.
Robert Crayhon: How does someone know if they can tolerate cereal grains? How do they know which ones suit them best?
Loren Cordain: I suspect that for most people, a simple subjective test can be conducted in which they reduce the amount of cereal grains in their diet and replace the grains with more fresh fruits, vegetables and lean meats and seafood. I do know that all human beings don't do very well when the total caloric intake of cereal grains approaches 70%.
The high phytate content of whole grain cereals can impair mineral metabolism i.e. iron, calcium, and other anti-nutrients have the potential to interact with the gastrointestinal tract and perhaps the immune system as well. The high lectin content of whole grain cereals can bind enterocytes in the small intestine and cause villous atrophy in addition to changing tight junction characteristics thereby allowing intestinal antigens (both dietary and pathogenic) access to the peripheral circulation.
Robert Crayhon: Those who recommend very high grain diets have no scientific basis?
Loren Cordain: Whole grain cereals are devoid of vitamin C and beta carotene (except for yellow maize). They have poorly absorbable vitamin B6, and the phytate levels in grains impairs the absorption of most of the divalent minerals. Additionally, they contain low levels of essential fats and have quite high omega 6/omega 3 fatty acid ratios. Excessive consumption of cereal grains are associated with a wide variety of health problems. In animal models, rickets are routinely induced by feeding them high levels of cereal grains. Hypogonadal dwarfism is found more often in populations consuming high (~50% of total energy) from unleavened whole grain breads (i.e. in Iran where they consume an unleavened bread called tanok).
Robert Crayhon: ....and where there's widespread zinc deficiency....
Loren Cordain: It is thought that the high levels of phytate in unleavened whole grain breads cause a zinc deficiency which in turn is responsible for hypogonadal dwarfism, along with other health problems associated with zinc deficiencies. In Europe, where immigrant Pakistanis consume high levels of unleavened whole grain breads, rickets among their children remains a problem.
Robert Crayhon: So this is rickets that has nothing to do with vitamin D deficiency, but with mineral deficiency?
Loren Cordain: No, both. Cereal grains seem to have a simultaneous influence on vitamin D and Ca metabolism.
Robert Crayhon: How do they alter vitamin D metabolism?
Loren Cordain: Epidemiological studies of populations consuming high levels of unleavened whole grain breads show vitamin D deficiency to be widespread. A study of radio-labelled 25 hydroxyvitamin D3 (25(OH)D3) in humans consuming 60g of wheat bran daily for 30 days clearly demonstrated an enhanced elimination of 25(OH)D3 in the intestinal lumen. The mechanism by which cereal grain consumption influences vitamin D is unclear. Some investigators have suggested that cereal grains may interfere with the enterohepatic circulation of vitamin D or its metabolites, whereas others have shown that calcium deficiency increases that rate of inactivation of vitamin D in the liver.
This effect is mediated by 1,25 dihydroxyvitamin D (1,25(OH)2D) produced in response to secondary hyperparathyroidism, which promotes hepatic conversion of vitamin D to polar inactivation products which are excreted in bile. Consequently, the low Ca/P ratio of cereal grains has the ability to elevate PTH which in turn stimulates increased production of (1,25(OH)2D) which causes an accelerated loss of 25 hydroxy vitamin D.
Robert Crayhon: So it doesn't get activated by the kidneys if there are a lot of cereal grains in the diet? The hormone version of vitamin D doesn't come into existence if people are eating 70-80% of their diets as cereal grains?
Loren Cordain: The mechanism still is unclear, however, the clinical response remains the same (overt rickets) in animal and human models. Here are some of the references if you are interested: (1. Batchelor AJ, Compston JE: Reduced plasma half-life of radio-labelled 25 hydroxyvitamin D3 in subjects receiving a high fiber diet. Brit J Nutr 1983; 49:213-16. 2. Clements MR, Johnson L., Fraser DR:
A new mechanism for induced vitamin deficiency in calcium deprivation. Nature 1987; 325: 62-65. 3. Dagnelie PC et al. High prevalence of rickets in infants on macrobiotic diets. Am J Clin Nutr 1990; 51: 202-8.)
Robert Crayhon: Are there particular grains that are more of a problem than others?
Loren Cordain: Wheat, rye, barley, and perhaps oats are problematical for individuals with celiac disease. Wheat seems to be associated with many auto-immune diseases. Ironically, whole grain cereals (which are thought to be more healthful than refined cereals because of their greater nutrient and fiber content) have a greater potential to disrupt mineral metabolism because of their higher phytate and anti-nutrient content.
Although high grain cereals intrinsically contain higher nutrient levels than do refined cereal grains, the biological availability of nutrients in whole grain cereals remains paradoxically low because of their high anti-nutrient content. On the plus side, whole grain cereals, because of their high fiber content tend to have superior glycemic indices than do their refined counterparts.
Obviously, low to moderate amounts of cereal grains in the diet presents little or no health problems to most people. The majority of the grain products consumed in this country are refined, and consequently many of the anti-nutrients are milled out.
Robert Crayhon: Such as the bran?
Loren Cordain: Yes, exactly. There's a trade off. Milling takes out the anti-nutrients, but it also lowers the levels of vitamins and minerals.
Interview reprinted by permission from Life Services
Dr. Loren Cordain, PhD, can be contacted at:
Professor, Department of Exercise & Sports Science
Colorado State University
Fort Collins, Colorado 80523 USA
The objections that many "experts" have to implementing a diet high in meat and protein and fat is that meat is not as readily available and is full of pesticides, growth hormones and antibiotics. It is much, much worse than this however!
Animals are fed grains extensively now, just like we are exhorted to increase our level of carbohydrates continuously by "Big Food" and vested interests because there is "Big Money" involved. The omega 6 to omega 3 ratios are nothing like what they should be in normal browsing animals. Even organic meat is little different when it comes to the Omega 6 ratio to omega 3. Around 20:1 as opposed to the 3:1 we are supposed to consume if you were to take the diet of our ancestors as the ideal diet for us.
Congratulations to Dr. Cordain who is perhaps the leading expert in the use of low grain low carbohydrate/natural meat diets for natural good health.
Dr. Robert Crayhon is also a nutritional biochemist.
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