Paleolithic Diet and Its Modern Implications: An Interview with Loren Cordain,
by Robert Crayhon, MS
by permission from Life
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 Robert Crayhon's interview with paleolithic
diet expert, Professor Loren Cordain, Ph.D.
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).
Loren Cordain is a professor of exercise physiology at Colorado State University
in Ft. Collins, Colorado, and is a reknowned expert in the area of Paleolithic
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.
My pleasure to be here.
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
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.
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 because 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.
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.
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
behaviorally 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.
Crayhon: What happened to our health when we switched from a hunter-gatherer
diet to a grain-based one?
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 anemia, 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.
Crayhon: Did we move from a hunter-gatherer lifestyle by choice, or were we
forced into the shift due to animal extinction?
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.
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
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.
How much cereal grain is too much?
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.
Crayhon: How does someone know if they can tolerate cereal grains? How do
they know which ones suit them best?
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
Crayhon: Those who recommend very high grain diets have no scientific basis?
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).
Crayhon: ....and where there's widespread zinc deficiency....
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.
Crayhon: So this is rickets that has nothing to do with vitamin D deficiency,
but with mineral deficiency?
Cordain: No, both. Cereal grains seem to have a simultaneous influence on
vitamin D and Ca metabolism.
Crayhon: How do they alter vitamin D metabolism?
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.
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?
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.)
Crayhon: Are there particular grains that are more of a problem than others?
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.
Such as the bran?
Cordain: Yes, exactly. There's a tradeoff. Milling takes out the anti-nutrients,
but it also lowers the levels of vitamins and minerals.
Crayhon: Some assert that too much protein, even beyond 60-70 grams per day,
is bad for people, will damage the kidneys and liver and cause bone loss. Yet
we find people groups around the world who eat a pound or more of meat per day
and don't seem to have any of these problems. What does you're research suggest?
Cordain: Epidemiological studies have suggested that increased animal protein
intake is associated with higher rates of osteoporotic fracture, and many metabolic
trials have demonstrated increased urinary calcium losses with increased protein
intake. However, in order to firmly establish cause and effect, and hence proof,
that a certain variable is responsible for a certain effect, scientists conduct
intervention trials. To my knowledge intervention studies have not been able to
show that a change from low/moderate to high protein intake increases that rate
of kidney stones or bone loss in either humans or animals.
age diets clearly were characterized by extremely high protein intakes by modern
standards, yet bone robusticity and density (determined from fossil paleolithic
humans) were greater than or equal to that of most modern humans despite the total
absence of dairy products in stone age diets. This seeming paradox (low calcium
intake, high protein intake yet strong dense bones) may probably be explained
by multiple factors. Stone age humans were more active than modern people and
consequently the everyday work they did resulted in greater bone loading, which
in turn can influence bone density. Further, they lived outside most of the day
so their sunshine exposure and hence vitamin D status would likely have been superior
to most modern people who work indoors and get little sunshine exposure.
Lastly, and most
importantly, the critical dietary factor influencing bone metabolism and hence
osteoporosis is not calcium intake, nor calcium excretion, but rather calcium
balance. The acid base status of the total diet rather than calcium intake or
excretion determines calcium balance (Barzel US. The skeleton as an ion exchange:
implications for the role of acid-base imbalance in the genesis of osteoporosis.
J Bone Miner Res. 1995; 10: 1431-36). Foods which yield a net acidic load mainly
as sulfates and phosphates cause the kidneys to respond to this dietary acid challenge
with net acid excretion, as well as ammonium and titratable acid excretion. Concurrently,
the skeleton supplies buffer by active resorption of bone. Consequently, calciuria
is directly related to net acid excretion (Barzel US, Massey LK Excess dietary
protein can adversely affect bone. J Nutr 1998; 128:1051-53). Foods which cause
a net acid excretion include meat, fish, cheeses and grains (Remer T, et al. Potential
renal acid loads of foods and its influence on urine pH. J Am Diet Assoc. 1995
Jul; 95: 791-97). Fruits and vegetables have a net alkaline value and consequently
reduce acid excretion and hence reduce calciuria thereby halting bone resorption
and actually allowing bone accretion to occur. Although the dietary calcium to
protein ration in stone age diets would have been quite low, the large amount
of fruits and vegetables (35% of total energy) included in the diet would have
produced a net dietary acid-base status which would have favored bone accretion
even in the face of enormous protein intakes.
nephro and urolithiiasis would have been reduced from the high levels of fruit
and vegetable consumption via their ability to reduce the potential renal acid
Crayhon: ...and they thrived and were very healthy on that.
Cordain: The fossil record and modern day studies of hunter gatherers suggests
this. Many populations around the world consume low fat, high carbohydrate diets
with little or no animal protein, yet paradoxically suffer high rates of diseases
of insulin resistance and high levels of cardiovascular disease. For example,
epidemiological studies of largely vegetarian Hindu populations from the Indian
sub-continent have shown mortality rates from cardiovascular disease that are
similar or greater than those rates found in European countries, despite their
Crayhon: And this is apparently due to the imbalance in their macronutrients?
Cordain: Yes, these populations tend to have very characteristic blood lipid
parameters indicative of syndrome X. They tend to have elevated triglycerides
and VLDL cholesterol and reduced HDL cholesterol. Also, the oxidative profile
of their lipids tends to be worse than the oxidative profile of some westerner
populations because cereal grains which have no vitamin C or no pro-vitamin A
beta-carotene may sometimes displace fruits and vegetables which are a rich source
of both of these antioxidants. Further, cereal grains tend to have a high Omega-6/Omega-3
ratio because they are high in linoleic acid and low in linolenic. The oxidizability
of the LDL molecule increases when it's loaded up with Omega-6 fats (linoleic
Crayhon: ...even though the Omega-3 fats are technically more delicate fats?
Cordain: Recent in vivo studies suggest this may not be the case.
This brings us to the enormous topic of the shift in the kinds of fats in the
Paleolithic even through the last centuries favoring the Omega-6's...safflower,
sunflower, corn oil, and arachidonic acid rich meats devoid of EPA/DHA as opposed
Cordain: This shift has only occurred in the last 80 years or so.
And what has happened because of that shift?
Cordain: The types of fats that you eat influence the type of fats that are
incorporated in the cell membrane. They can also influence hormonal profiles,
and eicosanoid function. We tend to see a more inflammatory eicosanoid profile
with elevated levels of Omega-6 fats.
Crayhon: And also arachidonic acids?
Cordain: The information is equivocal on arachidonic acid. Initial experiments
indicated that arachidonic acid had mainly deleterious effects. A recent metabolic
ward study of arachidonic acid indicates otherwise (Nelson GJ, et al. A human
dietary arachidonic acid supplementation study conducted in a metabolic research
unit: rationale and design. Lipids. 1997; 32: 415-420). Arachidonic acid is an
essential fatty acid in virtually every cell of the body, and it is an important
precursor for prostanoid synthesis and tissue function. More recent data suggests
that the balance of arachidonic acid to long chain Omega-3 fatty acid may be more
important in influencing health than absolute dietary intakes of arachidonic acid.
Crayhon: How much Omega-3 to Omega-6 should we have in our diet?
Cordain: In our laboratory, we have analyzed various tissues in wild game
meat and we have found that muscle tissue contains Omega-6 to Omega-3 ratio of
3.5-4 to 1. This ratio is higher in storage fat and bone marrow, and slightly
lower in certain organs. In the brain, this ratio is 1 to 1. Pre-agricultural
humans, as opposed to modern humans, enjoyed eating the organs of wild animals.
Certainly, they were eating the brains of the animals that they killed. The Omega-6
to Omega-3 ratio couldn't have been much lower than 4 to 1 if we only ate the
meat. If we only ate the brain, it would have been roughly 1 to 1. If fish were
included in the diet, it would have further reduced the 4:1 ratio found in the
muscle of terrestrial animals. Additionally, the inclusion of most plant foods
(but not all) would have also reduced the 4:1 ratio. The conclusion I have come
to is that the average Omega-6/Omega-3 ratio in pre-agricultural humans would
have always been lower than 4 to 1, but probably not lower than 2 to 1 depending
upon season, locale and macronutrient intake.
Crayhon: Looking at the food guide pyramid now with the Paleolithic perspective
that you've helped create, what would you do if you were to design an eating guide
for humans as a species?
Cordain: The evolutionary paradigm should be used a starting point for designing
optimal nutrition guides. Clearly, it is not practical nor economically possible
for all of the world's people to eat wild game, fruits and vegetables. However,
the macronutrient and trace nutrient levels that typically occur in reconstructed
Stone Age diets should be emulated in the design of healthful diets for modern
people. Humanity is totally dependent now upon cereal grains for survival. Cereal
grains provide 56% of the food energy and 50% of the protein consumed by all of
the world's peoples. Without them, there would be worldwide starvation of an unprecedented
proportion. we have wandered down a path of absolute dependence upon cereal grains,
a path from which there is no return.
Crayhon: So instead of 6-11 servings of these kinds of...well, on the pyramid
I think it's not just grain products but also potatoes and other sorts of carbohydrates
that are thrown in there. Would you recommend keeping 2-3 servings per day of
grain products or less? Or is it really hard to make any guidelines?
Cordain: I think that there is a significant amount of genetic variability
among people which may influence how well they do on various types of diets. Insulin-resistant
individuals do not seem to do well on high carbohydrate diets, particularly if
the carbohydrate has a high glycemic index. Generally, most people do quite well
healthwise on 2-3 servings of grain products per day. Clearly, cereal grains and
agriculture allowed for the dramatic worldwide human population expansion that
has occurred in the past 10,000 years since the advent of agriculture. I think
what the USDA is trying to do with its Food Pyramid is to give general dietary
guidelines that are beneficial for most people and which are economically feasible.
I think my work is not necessarily practical for making recommendations to all
of the world's people, but rather it points out how human diets may be improved
from an evolutionary perspective.
Crayhon: If you could speak to the modern health care practitioner, nutritionist,
or physician and tell them the key things Paleolithic research has taught us,
what might those be?
Cordain: Animal based diets can be healthful if designed with macronutrient
and trace nutrients that emulate those of our pre-agricultural ancestors. Low
fat, high carbohydrate cereal and legume-based diets are not necessarily healthful.
The implications of a Paleolithic diet are that humans tend to do quite well on
high protein animal-based diets in many regards including vitamin, minerals, and
fatty acid profiles. The whole concept of animal-based foods as deleterious needs
to be rectified. And the idea that if a little bit of whole grain is good for
you, then a lot should be better, needs to be reconsidered.
Crayhon: Why is it that so many people are so adamant about the negative effects
of animal products? Is it because of the extraordinary difference in quality between
a piece of wild game meat that may have 7-10% fat and fat of a high-quality, vs.
cornfed cattle that have 40% fat of a completely different nature? Is it the pesticides
or hormone residues in the meat? Is it all of the above?
Cordain: Wild game muscle averages about 2% fat by weight which translates
to about 15% by energy. Lean cuts of domestic meat may contain 5-7% fat by weight
and 30-35% fat by energy.
Crayhon: Even the well-marbled meats?
Cordain: Fatty cuts of domestic meat contain about 20% fat by weight and about
63% fat by energy.
Crayhon: Quite different from Paleomeat. Would a nice lean flank steak from
your supermarket be 7-10% fat?
Cordain: It could be slightly lower than that. There have been a couple of
studies that have shown that we are looking at the 5 to 7% range in a lean cut
of steak that has been cut of all visible fat, but remember this value is by weight.
Fat as a percent of total calories would be approximately 30-35%. As far as growth
hormones and pesticide residues, I think the evidence is equivocal and may not
be as important as the differences in fat content in terms of health and nutrition.
Because pesticides and heavy metals occur in areas that wild animals inhabit,
they are not entirely free of these toxins either.
Crayhon: So what I'm understanding that you're saying is that it's a far worse
thing to overdo carbohydrates and imbalance your diet than the chance of a minute
hormone or pesticide residue in your steak. It's more important to balance macro-nutrients...
Cordain: Generally, yes. Obviously if it were possible, it would be best to
eat wild game, meat free of pesticide, but I don't think that's a reality.
What's the best way to cook meat? How and when did Paleopeoples start cooking
Cordain: Organized stone hearths (and hence the first concrete evidence for
the control of fire) probably did not occur until the appearance of Neanderthals
roughly 200,000 years ago. So prior to this time, humans probably did not cook
their meat. I do not recommend, however, eating raw or slightly cooked meat because
of potential bacterial contamination.
Crayhon: What is the best way to cook meat?
Cordain: The way we tend to cook meat these days is very different from the
ways of hunters and gatherers who tend to slow-cook meats over a long period of
time. A favored cooking procedure was digging a pit and putting in hot stones,
putting in the whole animal or portions of it, putting in vegetable matter and
other stones above the vegetable matter and cooking the meat all day long. So
what is suggested is slow cooking at low heat.
Crayhon: Throw out the microwave and get a crock pot.
Cordain: Well, yes. If you take a lean cut of venison, elk, or buffalo, and
throw it on the barbecue, you'll find it's as tough as rubber but if you put it
on a crock pot or a Dutch oven and cook it all day long, you'll find that it will
come out quite tender and also, the nutrient content remains relatively high.
Also, you don't have to worry about bacterial problems.
Crayhon: I know you're doing some groundbreaking work right now looking at
the role of high consumption of grains as a possible trigger for many auto-immune
diseases. Can you comment on that?
Cordain: We don't have any clinical data at this point. We have a theoretical
model which points in many directions towards exactly what you're saying.
Are multiple sclerosis, lupus and rheumatoid arthritis rare in populations where
no grain products are consumed?
Cordain: Some epidemiological evidence would indicate exactly that. Part of
the problem in getting epidemiological evidence like this is that there are very
few populations on this planet that don't eat cereal grains...Prior to acculturation,
Eskimos and peoples of the far North were reported to have a low incidence of
auto-immune diseases. With acculturation, the prevalence of auto-immune diseases
are increasing in these populations and may approach Western levels.
we know that the expression of certain auto-immune diseases (e.g. insulin dependent
diabetes mellitus IDDM) increases in animal models when they are fed high cereal
grain diets. We believe that cereal grains may influence immune function by the
ability of their lectins (specifically wheat germ agglutinin-WGA) to allow passage
of undegraded dietary antigens and antigens derived from intestinal pathogens
(viruses and bacteria) to peripheral tissue. Through a process called molecular
mimicry, in which there are structural similarities between the body's own tissue
and that of the dietary antigen and/or the intestinal pathogen antigen, the immune
system loses the ability to distinguish self tissue from non-self tissue and mounts
an immune attack upon the body's own tissue. Many of these structural similarities
between cereal grain peptides and the body's own tissues seem to involve collagenous
Crayhon: Which grains have protein sequences closest to human collagen tissue?
Cordain: The literature suggests that the alcohol soluble portion of wheat
contains peptide sequences that may mimic peptide sequences in the body. But it's
a more complicated issue than that. It has to do with the genetics of the person
with the auto-immune disease as well.
Crayhon: The upshot of all this is that it couldn't hurt if you've got an
auto-immune disease to try a grain-free diet.
Cordain: Well, it's more than grain-free. We found again from a Paleolithic
perspective that humans didn't drink a lot of dairy, nor did they consume legumes
or yeast-containing foods. Dairy, legumes, and yeast contain peptides with amino
acid sequence that are homologous to amino acid sequences in a variety of human
tissues as well.
Crayhon: What about other foods such as fowl, fish, and fruits and vegetables?
Are these foods that are relatively free of these similar proteins?
Cordain: Generally speaking, most people don't have trouble with land based
flesh foods. Some people have trouble with shellfish or seafood from an immunological
perspective. Elimination diets tend not to use shellfish or fish, as some people
have trouble with these.
Crayhon: But as you've said, the grains, the dietary products, the legumes,
and yeast are the much more likely suspects. Any closing comments on the immune
problems caused by the agricultural revolution before we close our discussion?
Cordain: I think we need to have clinical trials obviously eliminating these
kinds of foods: cereal grains, dairy products, legumes, and yeast. This would
be difficult for people who have been weaned on a Western diet, but humans throughout
most of the course of our stay on this planet did not eat those foods or rarely
ate those foods. These proteins are alien to our immune system. We would hope
that clinical trials involving elimination of these suspect peptides will be done
in the future and hopefully may be of benefit to people with auto-immune problems.
Crayhon: Dr. Cordain, thank you for spending time with us today and sharing
these groundbreaking ideas with us. Your work embodies Stravinsky's phrase that
"revolution means going back all the way around to where you started from".
My pleasure, Robert.
Cordain, PhD, can be contacted at:
Professor, Department of Exercise &
Colorado State University
Fort Collins, Colorado 80523
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