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Eat
Right for Your Type?
The book
Eat Right for Your Type by Peter J. D’Adamo proposes that there
are four different ideal diets, one for each blood type: A, B, AB, and
O. Follow the diet that is ‘right for your type’, he says, and you can
lose weight, cure ear infections, fight off cancer, heal yourself from
Chronic Fatigue Syndrome, and much, much more. By ‘eating right for your
type,’ D’Adamo asserts, you will be eating like your prehistoric ancestors
did.70
This may sound very appealing. In a time
when we have strayed so far from a natural way of eating, a guide to eating
like your prehistoric ancestors could be quite helpful. And, indeed, many
have been drawn in by D’Adamo’s promises.
But according to the Tufts University Health
and Nutrition Letter, D’Adamo has his blood typing all wrong. “It’s a
fallacy even to speak of ‘original’ type Os or ‘original’ type As because
blood types did not originate with humans,” explains Dr Stephan Bailey,
a nutritional anthropologist at Tufts University. “They came on the biologic
scene long before humans did. Furthermore, there is no anthropologic evidence
whatsoever that all prehistoric people with a particular blood type ate
the same diet.”71
D’Adamo has come up with 16 different food
groups, further divided into ‘Highly beneficial,’ ‘Neutral,’ and ‘Avoid’
foods, depending entirely on what blood type you are. Type As, for example,
are told they do well on vegetarian diets, but they should avoid cabbage,
potatoes, eggplant, olives, peppers, and tomatoes, among many other foods.
They are, however, advised to eat snails.72
Type Os, on the other hand, are told to
base their diets heavily around red meat. They are told to avoid oranges,
apples, wheat, peanut butter, avocados, cabbage, and potatoes, but encouraged
to eat veal, ground beef, and beef heart.
D’Adamo tells Type Bs to eat a lot of dairy
products, including frozen yoghurt. He tells them to avoid sunflower seeds,
garbanzo beans, pinto beans, whole wheat bread, corn, pumpkin, tofu, tempeh,
and tomatoes, but encourages them to eat rabbit, lamb, and mutton.
Type ABs are told to avoid corn, peppers,
olives, sunflower seeds, sesame seeds, and lima beans, but encouraged
to eat jam, jellies, rabbit, and turkey.
Many people who have tried D’Adamo’s diet
have lost weight. There is a reason, but it isn’t the one he gives. In
actuality, the diets recommended for all four blood types are each extremely
low in calories. Some day’s plans have only 1,000 calories, half the caloric
needs of an adult woman.
Nevertheless, for D’Adamo, virtually everything
in life comes down to whether you are an A, B, AB, or O blood type. According
to him, “(ABO) blood type can determine so many things: how much and how
often we should eat; what our optimal daily schedule should be; what our
best sleep/rest patterns are; how stress affects us and how to combat
it; how to maximize our health; how to overcome disease; how we deal with
aging; and even our degree of emotional well-being.”73
D’Adamo believes that people who are type
O and type B must eat meat daily to be healthy. When confronted with the
fact that vegetarian diets have been consistently shown to produce lower
rates of cancer, heart disease, hypertension, diabetes, gallstones, kidney
disease, obesity, and colon disease, and to enable people to live longer
and more healthfully, he explains that type As do well on vegetarian diets.
It is, however, mathematically impossible that the health advantages for
vegetarians could be accounted for only by type As benefiting from the
absence of meat. According to the Red Cross blood bank, the population
of the United States is approximately 39 percent type A, 46 percent type
O, 11 percent type B, and 4 percent type AB.74
There is no possible way that the consistent superiority of vegetarian
diets that has been demonstrated repeatedly by world medical research
could be due to vegetarian diets having health advantages only for type
As, who are, after all, a minority of the population.
Similarly, D’Adamo’s explanation for the
success of Dr Dean Ornish’s program of reversing heart disease, which
includes putting people on a near-vegan diet with no meat, is that it
has only worked for type As. It does not, he says, help type Os, type
Bs, or type ABs.75
I asked Lee Lipsenthal, MD, the vice president and medical director of
Dr Dean Ornish’s Preventive Medicine Research Institute, whether this
might be possible. He replied,“There is no evidence in the scientific
literature associating blood typology with nutrient needs. Although heart
disease almost invariably gets worse, even when patients follow the American
Heart Association recommendations, most of our patients have shown actual
reversal of their disease, and the vast majority have shown measurable
improvement in many areas – improved physical function on exercise tests,
improved blood flow to the heart muscle, improved mood and sense of vitality,
improved cholesterol levels, improved blood pressure, improved sleep patterns,
and improved social function. We’ve had many hundreds of patients show
dramatic improvements, and all this has been measured by objective tests.
I don’t see any possibility that people with blood types 0 and B (who
together represent nearly 60 percent of the population of the U.S.) are
not being helped by the Ornish program.”76
D’Adamo believes that the risk of heart
disease for type Os is reduced by eating meat.77
There is, however, no evidence in the world medical literature for this
belief. The blood-type diet’s explanation for why type Os presumably need
meat is that type Os do “well on animal products and protein diets – foods
that require more stomach acids for proper digestion.” In fact, D’Adamo
says that “type Os can efficiently digest meats because they tend to have
high stomach acid content.”78
It is well known, however, that not all
men and women with type O blood produce more hydrochloric (stomach) acid;
some secrete normal levels and some have less than normal. Further, it
is pepsin, not hydrochloric (stomach) acid, that is responsible for meat
protein digestion. In people who have large amounts of hydrochloric acid,
the stomach environment becomes unusually acidic. An especially acidic
stomach actually make pepsin less effective at digesting protein.79
D’Adamo’s beliefs regarding the diets of
early humans, likewise, seem to have no basis in fact. He writes, ‘The
appearance of our Cro-Magnon ancestors in around 40,000 BC propelled the
human species to the top of the food chain, making them the most dangerous
predators on earth… (with) little to fear from any of their animal rivals…
(and no) natural predators other than themselves. Protein – meat – was
their fuel… By 20,000 BC Cro-Magnons had... decimated the vast herds of
large game.”80
The foundation of D’Adamo’s blood-type theory
is his belief that Cro-Magnons, who lived 40,000-20,000 years ago, were
all type Os and ate mainly meat. Types A, B, and AB came along later,
he says, and only they are genetically equipped for a diet that includes
grains. There is no evidence anywhere in the scientific literature, however,
that suggests Cro-Magnons were mainly or all type Os. Instead, there is
considerable evidence that all four blood types existed in the time of
the Cro-Magnons.
Were Cro-Magnons the heavy meat eaters D’Adamo
portrays? Not according to paleontologist Richard Leakey, who is widely
acknowledged as one of the world’s foremost experts on the evolution of
the human diet. Leakey points out, “You can’t tear flesh by hand, you
can’t tear hide by hand. Our anterior teeth are not suited for tearing
flesh or hide. We don’t (and Cro-Magnons didn’t) have large canine teeth,
and we wouldn’t have been able to deal with food sources that required
those large canines.”81
In fact, says Leakey, even if Cro-Magnons
had large canine teeth, they still almost certainly would only rarely
have eaten meat. Their diet would have been similar to that of the chimpanzee,
our closest genetic relative.
Molecular biologists and geneticists, Leakey
says, have compared proteins, DNA, and the whole spectrum of biological
features and have established very convincingly that humans are closer
to chimpanzees than horses are to donkeys. This is remarkable, because
horses and donkeys can mate and reproduce, although their offspring, mules,
are sterile. A significant difference between humans and chimpanzees,
though, is that chimpanzees have large canine teeth that can tear apart
their prey, and have more strength and speed than humans. Still, even
with these traits, which would be advantages for a meat-eater, chimpanzees,
like other primates, eat a mainly vegetarian diet. Dr Jane Goodall, whose
work with chimpanzees represents the longest continuous field study of
any living creature in science history, says chimpanzees often go months
without eating any meat whatsoever. Indeed, she says, “The total amount
of meat consumed by a chimpanzee during a given year will represent only
a very small percentage of the overall diet.”82
D’Adamo’s entire theory is based on his
assumptions about the blood types and diets of our prehistoric ancestors.
Even though his assumptions are wholly mistaken, however, his diet has
been embraced by many in the naturopathic community, and some schools
of naturopathic medicine have even begun to include this theory in their
curriculum. As a result, some naturopaths are now recommending that vegetarians
and vegans who are blood type O or B eat meat daily. However, other naturopaths
decisively disagree. The founder of naturopathy, Dr Benedict Lust, called
for “the elimination of… habits such as… meat eating.” Similarly, Henry
Lindlahr, MD, whose work has been widely read in naturopathic colleges,
defined naturopathy as favoring a ‘strict vegetarian diet.’ After a detailed
and thorough discussion of the blood-type diet’s underpinnings, contemporary
naturopaths Dr Deirdre B Williams and Dr John J McMahon conclude, “The
blood type theory of diet doesn’t have a leg to stand on.”83
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