many itinerations over the years, most
recently becoming popular in a form described in the book "Eat
Type" by Peter
D'Adamo, a naturopathic physician.
Unfortunately, this recent version is just as incorrect and harmful as
the ones that ancient societies embraced thousands of years ago.
The Blood Type Diet:
The blood type diet arbitrarily divides the human race into four
feeding types based on blood type, a kind of bizarre dietary caste
Blood group O is believed by D'Adamo to be the
"hunter" class. The author recommends they eat a high-protein diet
based on his idea that O was the first blood type to develop,
supposedly when a lot of hunting was going on.
Blood group A is said to be the "cultivator
class," by D'Adamo, who believes it evolved after the dawn of
agriculture 10,000 to 20,000 years ago. He suggest these people eat a
Blood group B is called the "nomad" group, and
associated with dietary flexibility such as the consumption of dairy.
Blood type AB is considered an enigma group by
D'Adamo, who suggests these people should eat a diet somewhere between
the cultivators and the nomads, which is pretty vague.
The Blood Type Diet: Where's the Science?
Although D'Adamo has a bibliography in, "Eat Right 4
Your Type," he
fails to specifically cite what science he bases his ideas on.
He claims or implies throughout the book that the biochemists and
glycobiologists he mentions support his view, but I find this highly
doubtful when the consensus among dietitians, physicians, and
scientists is that the Blood Type Diet is not scientifically-based (1).
Even the staid Mayo clinic concludes there's no science to
back up what D'Adamo says (2).
In fact, there are some significant blunders that bring into question
his understanding of nutrition.
On page 53, D'Adamo writes that hypothyroidism "occurs because Type O's
tend not to produce enough iodine." I bet there were thousands of
people that read that and started to freak out because they have type O
Iodine, of course, is not produced by the human body, and the only way
to get enough of it is to eat food grow in soils containing
iodine or animals who have taken it in themselves (6).
The Blood Type Diet Falls Apart When Logic Is Applied
Here's something that many
people don't stop to consider: All humans are animals. That we're the
most intelligent and prolific species on the planet doesn't change the
Yet every other animal on this planet has apparently been getting along
quite well with neither knowledge of their blood type nor what diet it
sentences them to. In fact, wild animals are notably free of diseases
and generally healthy, unlike our species.
There are generally believed to be three feline blood types (3), yet
cats, especially in the wild, eat from the same food groups unless
forced to do otherwise by humans or necessity.
All cats need taurine, and without it their health rapidly declines
(4). Taurine is found in animal protein (although recently humans have
artificially added it as a supplement to grain-based commercial cat
foods), and so the idea that some cats could have a vegetarian blood
type is absurd.
There are lots of cows in this world, but all of them eat grass.
Depending on where they are, they might eat some different kinds of
grass, but no blood beliefs will change the fact that they're
anatomically set up to digest grasses the best. You're not going to see
a subset of them hunting groundhogs.
There are multiple blood groups among apes, monkeys, chimps, and our
closest genetic relative, the bonobos (5). Yet each one of these
primate species chooses to eat the same type of food.
Bonobos, whose diet comes almost exclusively from wild fruits and
greens, will not adapt well to a meat or grain-based diet because they
lack the intestinal and enzymatic setup needed to process large amounts
of these foods. They may have such a diet forced on them while in
captivity, and, unsurprisingly, when this happens their health is often
subpar compared to their wild counterparts.
The Blood Type Diet And Humans
We've already established
that if humans had some sort of bizarre blood-food division, they would
be the only species to have it (or at least be aware of the possibility
that they might).
But let's assume for the sake of argument that humans have thrown off
the normal biological shackles that keep animals eating the same foods.
Where's the evidence?
Surely, if some humans are designed to eat high-meat diets and others
are meant to live off of plant food, where would be adaptations that
would set each of them apart, right?
For instance, the meat-eating humans should not get heart disease when
eating animal protein, just like carnivore species.
your Blood type? AB Positive? I so knew it! So am I! We were fated to
be together, and we can even eat the same food!"
Unfortunately, that's not the case. Cholesterol-containing animal foods
cause atherosclerosis to develop in all vegetarian-centric species like
humans, rabbits and chimps, but it does not do so in carnivore species
such as dogs and cats (11). Blood type doesn't have a role.
Anecdotally, I'm a type O who has been vegan since 2004, yet I've
apparently been fated to thrive on meat. I'm never ill and I've never
felt better, which is the complete opposite of my health when I was
eating meat. Room for exceptions, D'Adamo?
The evidence points to all humans requiring the same type of diet - a
The Blood Type Diet:
Why I Feel Bad For The
Humans are not equipped with the ability to digest the milk of other
species very well. It's estimated that 75 percent of the world's
population loses the ability to completely digest lactose after infancy
across the board. Decreased lactate
digestion ranges from as little as 5% in northern Europe, to
above 90% in some African and Asian countries (8).
Researchers theorize the species originally didn't drink the milk of
other animals, but that the adaptation to do so arose in east Africa
and northern Europe in response to populations shifting to pastoral
food systems to feed themselves (9).
But even though more than 92 percent of them can't digest milk well,
the Taiwanese shouldn't worry, because, after all, there are type
B blood types who among them can handle milk with aplomb. Right?
A fair sized chuck -23.9 percent - of them have type B blood, and not
all of them can fit into the 8 percent who can digest milk well.
So what are these Asians to do? According to D'Adamo, suck it up and
take it slow.
On page 37 of "Eat Right 4 Your Type", he suggests, "Type B's of Asian
descent may need to incorporate (dairy products) more slowly into their
diets as they adjust their systems to them.”
If you're lactose intolerant like me, you realize the consequences of
what he's suggesting. He's basically telling Asians to ignore the
camps, diarrhea, and possibly more serious conditions like colitis so
they can eat according to the arbitrary blood type diet he's created.
Apparently they'll magically adjust over time due to the power of their
The Blood Type Diet: The
The Blood Type Diet amounts to a modern day astrology that imposes some
strange, unscientific divisions on humanity.
Although our species can manage to digest a number of foods, science
makes it pretty clear that we're best equipped to eat plant foods
almost exclusively. Our health suffers when we do not.
1) Human blood
cells: Consequences of genetic polymorphisms and variations, pg. 44. 2) What is the
blood type diet? And is there any merit to the blood type diet? The
Mayo Clinic: http://www.mayoclinic.com/health/blood-type-diet/AN01415 3) Giger U; Kilrain
C.G. Filippich L.J. et al. (1989). "Frequencies of
feline blood groups in the United States.". Journal of the American
Veterinary Medical Association 195 (9): 1230–1232. PMID 2584120. 4) Nutrient
Requirements of Cats, Revised Edition, 1986. 5) Socha WW. Blood
groups of apes and monkeys: current status and practical applications.
Lab Anii. 1980 Aug;30(4 Pt 1):698-702. PMID 6775134. 6) Andersson M,
Takkouche B, Egli I, Allen HE, de Benoist B (2005). "Current global
iodine status and progress over the last decade towards the elimination
of iodine deficiency". Bull. World Health Organ. 83 (7): 518–25. PMID
16175826. 7) "Improved
lactose digestion and intolerance among African-American adolescent
girls fed a dairy-rich diet.". Journal of the American Dietetic
Association. 2000. 8) Bulhoes, A. C.,
et al. (2007-11). "Correlation between lactose absorption and the
C/T-13910 and G/A-22018 mutations of the lactase-phlorizin hydrolase
(LCT) gene in adult-type hypolactasia". Brazilian Journal of Medical
and Biological Research. 9) Coles Harriet
(2007-01-20). "The lactase gene in Africa: Do you take
milk?". The Human Genome, Wellcome Trust.
http://genome.wellcome.ac.uk/doc_WTX038968.html. Retrieved 2008-07-18. 10) Kretchmer N
(1972). "Lactose and lactase". Sci. Am. 227 (4): 71–8. PMID 4672311. 11) Harper's
Biochemistry 24th edition. Page 280
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