Interview with Loren Cordain, PhD
"E-mail to a friend"
by Dr. Robert Crayhon, MS
Reprinted by permission from
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.
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).
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.
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.
Cordain: 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 for humans?
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
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.
consume too many Omega-6 fats and not enough Omega-3 fats.
Omega-6/Omega-3 ratio in western diets averages about 12:1.
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:
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.
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.
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.
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.
appearance of milling stones was in the Middle East roughly
10-15,000 years ago.
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.
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.
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 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
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
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?
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.
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.
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
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.
health and well being can be optimized when we use the
evolutionary paradigm as the starting point for present day
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
Crayhon: 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%.
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.
Crayhon: Those who recommend very high grain diets have no
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.
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?
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:
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:
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.
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.
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.
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
Dr. Loren Cordain, PhD, can be contacted at:
Professor, Department of Exercise & Sports Science
Colorado State University
Fort Collins, Colorado 80523 USA
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!
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.
Robert Crayhon is also a nutritional biochemist.
Stem Cell Research Breakthrough