Palaeolithic Nutrition?
Introduction
The Palaeolithic Diet has been popularised primarily because of research by
S.B. Eaton and M. Konner that advocates a hunter-gatherer diet for humans. A
large volume of literature has been produced out of this hypothesis, one of
many which are arising through the logical application of evolutionary
theory to nutrition. The idea is that humans are adapted to the higher
animal product diets that they ate as "cave men" for hundreds of thousands
of years. It quite rationally proposes that humans have not adapted to the
Standard Western Diet (SWD), or indeed to any of the diets that are a
consequence of Neolithic developments - that is, ones including the
consumption of cultivated grains, dairy products, over fatted animal
carcasses, salt and so forth. The traditional Australian aborigines and the
!Kung San peoples of the Kalahari dessert are often suggested as
contemporary models for the diet.
The Weak Hypothesis of Anthropologists
One well known advocate of the diet, Dr. Loren Cordain, author of "The Paleo
Diet" (1) claims that hunter-gatherer populations have much lower incidence
of chronic degenerative diseases than modern Westerners, for example
cardiovascular events are much more rare in contemporary hunter-gatherer
societies than in peoples eating the SWD. The suggestion is that this is a
result of superior nutrition. The Palaeolithic diet was characterised by
wild game which is generally lower in fat than modern commercial meat, and
has preferential fatty acid and vitamin profiles. Palaeolithic wild gathered
fruit and plant matter was suposedly nutritionally superior to modern day
grain type plant foods, and plant foods grown under commerical conditions in
general. The case for this is fairly convincing, although quite how one
properly takes into account the many very different lifestyle factors
between modern humans and Palaeolithic ancestors, is not clear. Indeed, a
general lack of clarity and precision characterises the whole topic of
Palaeolithic nutrition, which is inevitable given the nature of the
available information - i.e. very little. So projecting from the
Palaeolithic experience to modern humans, is fraught with potentially
serious issues of interpretation and extrapolation.
Although we may be lead to believe that the Palaeolithic diet has a
scientific basis, Loren Cordain makes a rather poor case for the diet in his
book. The scientific reader given a "hypothesis" can reasonably expect to be
provided with precise definitions, supporting facts and logic, and an
unbiased approach that appraises all the relevant data and makes well
reasoned assumptions. The opening prose explain the basis of the hypothesis
along the lines that modern humans are clearly not adapted to their modern
diets because of the high prevelence of diet related diseases. However, this
fact does not demonstrate that Palaeolithic peoples were adapted to their
diet. Cordain fails to define what dietary adaptation actually is, and how
we might test for it. He fails to provide any specifics in his hypothesis,
which of course makes it hard to test. He claims that people don't realize
"how healthy Paleolithic ancestors were" and then fails to provide evidence
that they were healthy. Instead he claims they were free from heart disease
and other chronic ailments that plague modern Westerners, but that does not
demonstrate that Palaeolithic people were healthy, anymore than does his
claims that hunter-gatherers look lean and fit in the many photographs that
Cordain has seen. Even modern day world class athletes have competed
successfully with advanced cancer. Cordain cites the Yanomamo Indians for
their low blood pressure, but of all the hunter-gatherers, these perhaps eat
the least animal products and are sometimes said to be close to vegetarian.
The Yanomamo also practice forest gardening, a primitive form of
agriculture. So the intoduction that Cordain gives us to his ill defined
hypothesis is a series of non sequiters and unsupported claims. The book
then follows with one after another of unsupported claims and logical
fallacies. Cordain often displays his own personal prejudices in the
material presented in the book. Cordain does not tell us why humans had to
wait to develop technology before they could eat the diet they were
allegedly "designed" to eat.
Cordain repeats the oft made claim of anthrpologists that meat is "brain
food", and goes even further suggesting that our our ancestors meat habit
somehow lead him to become a scientist. However, scientific philosophy only
arose after the Palaeolithic era, and is not present in any stone age
society, and of course it cannot be so. Science arose along with the
develoment of agriculture, which is almost a science, and the eating of less
meat. So does Cordain demonstrate that the hunter gatherer high meat diet
necessitated the development of agriculture and science? That hunting and
gathering necessarily lead to the development of agriculture is also
questionable, given the existence of hunter-gatherer societies up until
recently. It is possible that the high pressure that over hunting and
gathering places on the environment with a growing population necessitated
agriculture, but that is no case for meat eating, or meat as a brain food.
The need for humans to develop tools in order to process animal foods is
perhaps a rather better theory. While the historical basis of the argument
seems weak (correlation doesn't identify causation), the case for DHA, a
fatty acid, sounds more scientifically plausible. As yet though, DHA is not
recognised as an essential fatty acid, except parhaps in growing children
who may obtain it from breast milk. On the web site Cordain does mention
some studies that show better outcomes when developing children have access
to DHA, but this could be suggestive that a prolonged period of breast
feeding is beneficial, or simply that the standard diet does not promote
sufficient DHA synthesis - and that could be for a variety of other reasons
beyond DHA provision in the diet. In any case, the point simply is not
proven by any of Cordain's works. Furthermore, there is no exploration of
the possible detrimental effects of meat consumption on brain development
and function.
As we shall see later, there is evidence that stone age dieters suffer from
gastric ailments that are common nowadays. However, Cordain believes that a
diet high in animal products is not constipating. If this were true, then
this would be a major blow to the idea that humans were adapted to a
Palaeolithic diet. The case he presents though, is remarkably unconvincing,
and relies on weak evidence and some flawed reasoning. Cordains first piece
of evidence relates an anecdote about Arctic explorer Vilhjalmur Stefansson
who sometimes lived exclusively on animal products. He had found that
constipated men who had been eaten refined cereal foods were relieved of
their condition when they tried the menu of the "Eskimos". However, this
diet is unusual in that it includes a lot of oily fish and blubber, which
are of course excellent lubricants. Even so, the Innuit are no strangers to
constipation. One of the most powerful spirits in Innu mythology is
Matshishkapeu (translated "fart man"), who can control other spirits by
inflicting deadly bouts of constipation upon them. The Innu people of
Labrador also have herbal remedies for constipation, colds and other
ailments common to more civilised peoples.
In citing Stefansson, Cordain uses a worst case scenario comparison, and of
course this always presents things in a biased fashion. A fair comparison is
not between a person on an entirly unnatural diet of refined cereals such as
a sailor or arctic explorer, but rather, with people eating a diet high in
natural plant fibres who then add meat to their diet. It is common knowledge
that red meat is constipating, for example The Constipation Resource Center
gives the advise to "Limit your consumption of meat" in cases of
constipation. How then is meat a cure for constipation? Clearly it is not.
Perhaps Stefansson and his men could have got the same result if they just
ate grease or oil, or of course some fruit or other source of plant fibre.
To further support his claims, Cordain then reports how Stefansson returned
from his arctic exploration and then repeated his all-meat diet and was
observed by physicians to have "normal" bowel function. (Stefansson died at
age 83 due to stroke.) Furthermore, in the experiment with Stefansson and
his friend, they confirmed that they only had satisfactory bowel function
when they ate a meat only diet including all the fat. They reported that
when they cut the fat out, they had digestive problems. Cordain advocates
removing the fat to cut the risks of atherogenous diseases. The Paleo choice
seems to be constipation or arterial disease.
Cordain also suggests that humans are not intended to eat a plant based diet
because of the evolutionary evidence and the anthropological record. As we
shall see later, human evolution is clearly indicative of a herbivorous
lineage. Using the anthropological record is flawed reasoning ("argumentum
ad antiquitatem"), what was done isn't necessarily what should have been
done. Furthermore, we don't really have any precise evidence of what our
evolution actually was. Instead we have some bone fragments of which rather
subjective, and often changing interpretations are made - what Jared Diamond
referred to as "paleopoetry" (The Rise And Fall of The Third Chimpanzee,
Jared Diamond, p.70, Vintage Science).
While the above is not an exhaustive critique of the ideas presented by
Cordain, it is at least enough to expose his fundamentally unscientific
approach. That Cordain claims to be a scientist, and presents this kind of
clearly prejudicial selection biased evidence, should be reprehensible to
any reasonable person. Cordain could be forgiven for not presenting a blow
by blow account of his research findings in what is austencibly a recipe
book, but the kind of rubbish he does present is hardly worthy of repeating.
Cordain fails to link the reference material in his bibliography to the many
claims he makes in the main text.
The Problem of Uncertainty
We have no medical records (no morbidity data) from the Palaeolithic era, so
no way of telling whether Palaeolithic man was really healthy or not.
Looking at bones and teeth may show that these humans were often well
nourished, but that is all. If they died of cancer, heart disease, gall
bladder complications or other organ pathology, we would not expect to see
evidence of that in the bones. In any case, these diseases tend to kill
outside the expected lifespan of Palaeolithic man, so we could never
discover their real susceptibility, even if we had soft tissues to examine.
Modern humans live longer in a different world, and may require a more
carefully chosen diet in order to remain free from degenerative diseases.
The Palaeolithic diet is akin to a creationist ideology. It is devoid of
robust definitions, a testable hypothesis, and finds its basis in the
personal beliefs and prejudices of its authors. Huge claims are made which
are unsupported by factual evidence, while at the same time facts that crack
the dogma open, are either ignored or papered over.
Human Dietary Adaptations
The Paleo diet rather assumes that we "adapted" to what our alleged
ancestors ate during the Palaeolithic period. What about the prior billions
of years of evolution of eating a totally raw diet without the higher meat
availability from hunting and the related technology? What strong evidence
is there of any adaptations to Palaeolithic eating patterns? A paper by
Caleb E. Finch and Craig B. Stanford, published in the The Quarterly Review
of Biology (2), suggests that humans have indeed made some small biochemical
inroads into adapting to a diet including more meat. They suggest that up to
eight genes in humans allow for greater protection from the degenerative
effects of consuming meat. From this study, we may infer that humans will
suffer less damage from meat eating than they would otherwise, but this is
far away from suggesting that it is beneficial overall for humans to eat
meat, rather the adaptation is alleged to offset degenerative disease
events. The existence of a protective mechanism isn't evidence of benefit
from the chemical insult it protects against. For example, the existence of
a protective mechanism against cyanide in our liver, does not mean we should
ingest cyanide, although it does mean we are "adapted" to cyanide in the
diet. The same principle applies to this meat eating/adaptive hypothesis,
and the researchers make it very clear that these are protective adaptations
in their work.
Above is the best evidence in favour of humans being meat eaters. What is
the evidence against the idea? On page 280 of Harper's Biochemistry 24 Ed.,
a medical students text, we discover that "The rabbit, pig, monkey, and
humans are species in which atherosclerosis can be induced by feeding
cholesterol. The rat, dog and cat are resistant." Therefore, it seems there
is something fundamentally different between human biochemistry and that of
species that naturally consume high amounts of animal products, and of
course, humans do suffer from atherosclerosis. Much of this will be because
of the high intake of saturated fats and a low intake of protective vitamins
in SWD, which would not be such an issue for Palaeolithic humans. However,
without medical evidence that they were free of the disease - what are we to
assume? We don't even have in depth medical studies on the diseases of
contemporary hunter-gatherers, let alone long deceased ones. Although
dietary cholesterol isn't as great a problem it was once thought to be to
most of us, cholesterol oxidises in animal products, and oxidised
cholesterol is still thought to be problematic (3) as well as saturated
fats. Meat also contains small amounts of trans-fats (4) that would raise
LDL cholesterol slightly, thus increasing risk of heart disease. Therefore,
we would expect to find heart disease amongst the hunter-gathereres who eat
the most meat. Cordain however, suggests that the paleo diet improves blood
lipid profiles when compared to a Western diet, because of factors such as
better essential fatty acid intakes, and because in Western diets refined
carbohydrates and high fat intakes both work together to elevate serum
cholesterol. He also suggests that calorific restriction (i.e. lack of
food), as well as greater physical activity helps to lower cholesterol
levels in hunter-gatherer societies. These factors need teasing out in order
to make a case for the diet outside that of the overall lifestyle.
"Although saturated fat is the main dietary culprit that raises LDL, trans
fat and dietary cholesterol also contribute significantly. ... Dietary
cholesterol also raises LDL cholesterol and may contribute to heart disease
even without raising LDL. ... Health experts recommend that you keep your
intake of saturated fat, trans fat, and cholesterol as low as possible while
consuming a nutritionally adequate diet." (4)
The big question is of course, just how good is a hunter-gatherer diet at
lowering cardivascular risk in reality? Does the theory really work? In a
paper called "Diet of Aboriginal hunter-gatherers" Kerin O'Dea (5) reveals
that traditionally fed Aborigines had cholesterol concentrations of about
3.9 mmol/l (about 150 mg/dL vs. 210 mg/dL for an average American) . O'Dea
also reports that traditionally living Aborigines have inappropriately
elevated insulin and tryglyceride levels, and that this is consistent with
insulin resistance. This could be because of iron overload, which is
discused below. However, there was no evidence of diabetes or coronary heart
disease. When cholesterol levels are below 150 mg/dL, then coronary heart
disease is virtually unknown (T.C. Campbell, personal communication). In
this respect Palaeolithic diet seems to be a success. However, it would be
misleading to suggest that it is necessary to follow a Palaeolithic diet to
get these results. Similar results can also be achieved using a low fat,
plant based diet with without or with minimal animal products such as fish
or fish oil or a source of plant omega-3 fats such as flax oil. This program
has been used by Dr. Dean Ornish, and is actually effective in reversing
atherosclerosis without drugs. Cholesterol levels below 150 mg/dL, average
for 130 village 127 ± 15 mg/dL, were also normal in rural Chinese
populations according to a large ecology study (6), and in these
populations, heart disease and other diseases of afluence where the lowest
in the world.
Primary hyperoxaluria type 1 (PH1) is a recessive disease in which an
enzyme, alanine:glyoxylate aminotransferase (AGT), is mistargetted from the
peroxisomes where it functions in the glyoxylate pathway, to the mitochondia
(7) where it is inefficient. It can be caused by defects in at least two
glyoxylate-metabolizing enzymes and leads to excessive urine oxalate
excretion resulting in kidney stones and/or calcification of the kidney
which can occur in childhood or adolescence. Patients used to die on average
at age 36 (8), however modern therapeutics can help to increase lifespan in
certain forms of the disorder. According to Christopher Danpure and
associates, "One molecular adaptation to diet that is spread widely across
Mammalia is the differential intracellular targeting of the intermediary
metabolic enzyme alanine:glyoxylate aminotransferase (AGT), which tends to
be mitochondrial in carnivores, peroxisomal in herbivores, and both
mitochondrial and peroxisomal in omnivores." (9) As humans normally express
this gene effectively in their peroxisomes only, humans are classed along
with herbivores in respect of AGT expression, as are chimpanzees. AGT
assists in the detoxification of glyoxylate, the precursor of which is
thought to be glycolate from plant foods, and hydroxyproline in meat.
Glyoxylate forms in the peroxisomes from glycolate and in the mitochondria
from hydroxyproline. If glyoxylate oxidises, it becomes oxalate which is
prone to crystallise out in the kidneys, where it causes blockages.
Further evidence that humans don't seem to have adapted to meat eating is
the higher prevalence of diabetes and heart disease amongst meat eaters in
modern populations. In modern populations, controlled studies show that
increasing plant foods tends to decrease mortality, whereas increasing
animal foods increases mortality from the common degenerative diseases.
Studies comparing vegetarian and meat eating populations have shown that a
vegetarian diet can lower risk of diabetes (10). One factor linked to the
risk is the type of iron found in red meats, "heme-iron". When the body
builds up excessive stores of this form of iron from red meat, then risk of
diabetes increases (11), particularly when intakes of protective nutrients
are low. The human body is ultra efficient in its preservation of iron
status, and has no natural means of excreting any great excess. Daily losses
of iron are so low, normally around 1 milligram, that it is necessary to
keep meat intakes low in order to avoid excess. This may be less an issue
for Palaeolithic humans, because of intestinal parasites that also take up
dietary heme-iron and even iron directly from the gut of the host (see CDC
discussion below). A 100 gram cut of beef may contain as much as 1.9mg of
iron, much of which is highly absorbable heme-iron, wild game probably
contains more. The heme-iron found in meat is not subject to the tighter
regulatory control that non heme-iron is, through binding proteins and other
control mechanisms. These mechanisms are effective in preventing iron
overload even when large quantities of iron is ingested from plant foods, or
even contaminating soil. However, when red meat is eaten as part of a SWD,
the risk of fatal heart attack rises proportionally (12). The availability
of iron from plant foods can be improved significantly (300-400%) when
vitamin C intake is high, because vitamin C neutralises the inhibitory
effects of polyphenols and phytates found in some plant foods, particulalry
grains. Therefore failure to absorb sufficient iron from plant foods can
indicate inadequate vitamin C OR iron intake. Unfortunately, the practice of
cooking food reduces vitamin C content of foods by between 20-90%.
Palaeolithic humans probably ate more fresh and raw plant foods than typical
modern humans, so ensured a greater intake of protective nutrients such as
vitamin C.
Doesn't the higher absorption capacity of heme-iron in humans suggest that
we are adapted to eat animal products? This hypothesis certainly does not
appear in any credible research literature. However, a very different
explanation is provided by the CDC (13). Each day the digestive system loses
thousands of its surface cells, and the heme-iron in these cells potentially
becomes available as a crucial nutrient for gut pathogens. Effective
absorption of heme-iron in the digestive system is therefore a necessary
part of our immune system, and known as the "iron withholding defence system
". The CDC specifically lists excessive consumption of red meats as a
condition that can compromise iron withholding, and therefore resistance to
invading parasites. This iron withholding system is common to all mammals
(i.e. includes all herbivores), and so is nothing to do with a specific
dietary adaptation.
Longevity
Another issue is longevity. Palaeolithic humans are not thought to have
lived so long as modern humans, but it is hard to know how long Palaeolithic
humans lived. Even eating a SWD, you might expect to live into your 70s, or
rather longer as happens in some Asian populations, who incidentally, eat
very little food of animal origin. The same cannot be said for the lifespans
of hunter-gatherers in the recent past or present. For example, some
estimates suggest a life expectancy of Pleistocene humans as well under 25
years (The Cambridge Encyclopedia of Human Evolution, p. 406). Modern
hunter-gatherer societies may not be realistic models for Palaeolithic
humans either, because of contact with modern culture, and further
development of their own cultures since Palaeolithic times. Modern
hunter-gatherer societies are the result of Palaeolithic developments. If
they are used as models, their average life expectancy and upper life
expectancy compared to modern humans is still rather poor. These differences
might not be so much to do with diet, but then maybe they are?
Diseases of Contemporary Populations Eating Stone Age Diets
While we don't have any good data on the real state of health of
Palaeolithic humans, we do know that contemporary hunter-gatherer peoples
are not healthy. Human cultures seem to have a variety of bizarre healing
systems (a.k.a. "witchcraft", "black magic", "herbalism"), some of which
have useful treatments, but most of which are ineffectual (or highly
dangerous) and based on false beliefs. For example, the Australian
aborigines traditionally live a hunter-gatherer lifestyle and have a herbal
medicine (14) that predates Western contact, and is probably quite ancient.
It has treatments for symptoms of colds and flu, gastro-intestinal disorders
(bad diet?), congestion, coughs, generally feeling unwell, sore throat and
so forth. The traditional North American aboriginal medicine also has
remedies for diseases of the digestive systems such as hemorrhoids (see
below), which is now a very common disease in modern populations, yet is
almost non existent in wild animals. This demonstrates that hunter-gatherers
suffer from many of the ailments common to contemporary populations,
including those undoubtedly caused by inappropriate diet, such as
hemorrhoids. As with any other species eating its correct diet, healthy
humans have no need of these complex medical cultures or any of these
remedies. Means of dealing with accidental injuries is all the medical
culture a healthy human society would develop.
"Witch hazel preparations have a long history of traditional use in North
America (Der Marderosian, 1999; Duke, 1985). The aqueous infusion of the
bark was used in aboriginal medicine to treat hemorrhages, inflammations,
and hemorrhoids (Millspaugh, 1974)"
Witch Hazel leaf and bark, herbalgram.org, American Botanical Council
"Sanguinaria canadensis L.
Bloodroot; Papaveraceae
Iroquois Drug (Hemorrhoid Remedy)
Decoction of roots used to push piles back into intestines.
Herrick, James William 1977 Iroquois Medical Botany. State University of New
York, Albany, PhD Thesis (337)"
Native American Ethnobotany Database
What about the !Kung San as a model for hunter-gatherer health? Again the
evidence for health isn't convincing. The !Kung San believe that everyone is
inherently ill, and it is common for a large proportion of tribal members to
be shamanic healers. When you read about the !Kung San, it seems that they
have a culture that is paranoid about illness. This is perhaps not
surprising as survival in the remote and often extremely arid areas they
live in, must be far from easy. These conditions may not model the
Palaeolithic human condition at all well, but whether they do or not, no
evidence of good health has been produced. We simply cannot translate their
experiences into a modern human world.
A more representative picture of how cave men probably lived is given by the
Andamanese peoples as theirs is the most ancient surviving way of life on
earth. For example the Onge tribe of the Andaman Islands, until recently,
lived an almost undisturbed way of life that fits the Palaeloithic model.
The men hunt wild boar, but they also fish, and women gather wild tubers and
burries. They tend to boil their food in large pots, in this respect they
must differ from the earliest Palaeolithic ancestors, however food must be
relatively abundant when compared to other contemporary hunter-gatherer
societies from arid regions. According to a source quoted by The Andaman
Association Switzerland (15), the Andamanese suffered most from "coughs and
cold, ague, fever, and severe headache", and they also mention that diseases
known to have been common in the Andamanese before 1800 were malaria,
catarrh, coughs, rheumatism, tuberculosis, pneumonia, and perhaps most
signifcantly heart disease. Some of these ailments may be a consequence of
outside contact, but not all. The Andamanese seem unaware of good hygiene
practices, so presumably are also like cave men in this regard. Once again,
it is difficult to project these findings into a contemporary situation.
However, it is notable that these peoples suffered from diseases associated
with the Standard Western Diet, and in particular it seems, of high meat
consumption.
Conclusions
The "empirical method" is the hallmark of contemporary science. That is, a
hypothesis such as the Palaeolithic diet needs to be tested experimentally
in controlled conditions in order to develop a convincing theory. At present
there is no empirical evidence to suggest that modern day humans who adopt a
Palaeolithic diet will have good health, or significantly reduce their
chances of degenerative diseases in the same way as hunter-gatherers are
sometimes alleged to have. Modern humans live in very different
environmental conditions to traditional hunter-gatherers, and it simply does
not follow that we can adopt hunter-gatherer nutrition and be healthy.
In summary: 1) no evidence that a Palaeolithic diet is healthy, 2) no real
evidence of adapting properly to a high meat diet, 3) some good evidence
that humans didn't adapt to the diet and 4) are unhealthy on hunter-gatherer
diets, as well as on modern diets including high meat consumption. Taking
these points into account, the "cave man" diet really looks like a
discreditable hypothesis. Perhaps the "Paleo" diet is rather better than a
Standard Western Diet, but there is no case for it being natural, or optimal
for us, by a long way.
References
The Paleo Diet, Loren Cordain
http://www.thepaleodiet.com
The Quarterly Review of Biology, March 2004, Vol. 79, No. 1, Meat-adaptive
Genes And The Evolution Of Slower Aging In Humans, Caleb E. Finch, Craig B.
Stanford
http://www.journals.uchicago.edu/QRB/journal/issues/v79n1/790101/brief/790101.abstract.html
Dietary Cholesterol Makes LDL Cholesterol More Radical, Judy McBride, April
4, 2000, USDA Agricultural Research Centre
http://www.ars.usda.gov/is/pr/2000/000404.htm
Revealing Trans Fats, FDA Consumer magazine, September-October 2003 Issue,
Pub No. FDA03-1329C
http://www.fda.gov/fdac/features/2003/503_fats.html
Phil. Trans. R. Soc. Lond. B (1991), Diet of Aboriginal hunter-gatherers, K.
O'Dea, p. 74
Chen J, Campbell TC, Li J, Peto, R. 1990. Diet, life-style and mortality in
China. A study of the characteristics of 65 Chinese counties. Oxford, UK;
Ithaca, NY; Beijing, PRC: Oxford University Press; Cornell University Press;
People's Medical Publishing House, 896 pp.
J Nephrol. 1998 Mar-Apr;11 Suppl 1:8-12, The molecular basis of alanine:
glyoxylate aminotransferase mistargeting: the most common single cause of
primary hyperoxaluria type 1, Danpure CJ
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9604801&dopt=Abstract
Primary Hyperoxalurias, Mayo Clinic College of Medicine
http://mayoresearch.mayo.edu/mayo/research/nephrology/hyperoxaluria.cfm
Mol. Biol. Evol. 21(4):632-646, 2004, Differential Enzyme Targeting As an
Evolutionary Adaptation to Herbivory in Carnivora, Birdsey GM, Lewin J,
Cunningham AA, Bruford MW and Danpure CJ
http://mbe.oupjournals.org/cgi/content/abstract/21/4/632?ct
Eur J Clin Nutr. 2004 Feb;58(2):312-6, Insulin sensitivity in Chinese
ovo-lactovegetarians compared with omnivores, Kuo CS, Lai NS, Ho LT, Lin CL
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=14749752
Am J Clin Nutr. 2004 Jan; 79(1): 70-5, Dietary iron intake and blood
donations in relation to risk of type 2 diabetes in men: a prospective
cohort study, Jiang R, Ma J, Ascherio A, Stampfer MJ, Willett WC, Hu FB
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=14684399
Am J Epidemiol. 1999 Mar 1;149(5):421-8, Dietary iron and risk of myocardial
infarction in the Rotterdam Study, Klipstein-Grobusch K, Grobbee DE, den
Breeijen JH, Boeing H, Hofman A, Witteman JC
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=10067901
CDC, Iron Loading and Disease Surveillance, Eugene D, Weinberg, Indiana
University, Bloomington, Indiana, USA
http://www.cdc.gov/ncidod/EID/vol5no3/weinberg.htm
Traditional Aboriginal Medicine Practice, Dr Dayalan Devanesen AM, MBBS, DPH
(Syd) Grad. Dip MGT, MHP (NSW) FRACMA, FAFPHM, FCHSE
http://www.nt.gov.au/health/comm_health/abhealth_strategy/Traditional%20Aboriginal%20Medicine%20-%20Japan%20Paper.pdf
In Sickness and in Health, Chapter 19, The Andaman Association, Switzerland
http://www.andaman.org/book/chapter19/text19.htm