Eat Right for Your Health (blood types and diet)
gene cass
types should only eat certain foods?
EJ
> Has anyone proven this theory proposed by Dr. D'Adamo that certain blood
> types should only eat certain foods?
Here is your answer:
The Blood Type Diet
The “blood type diet” theory has gained widespread attention from the public
since the release of “Eat Right For Your Type”
by Peter J. D’Adamo, N. D. (G. P. Putnam’s Sons, New York, 1996). The book's
basic premise - that Type O's are the
dominant, hunter-caveman type that require meat in the diet, that Type A's
are docile vegetarians, while Type B's are
dairy-eating omnivores - has become a manifesto for many people to
rationalize including regular portions of meat and other
animal products in their diet. ("After all, my ancestors did it.")
However, the "blood type diet" theory, and the book that
promotes it, presents many problems that prevent me from seriously basing
any of my dietary choices upon them.
One of the book's most disturbing characteristics is the frightening images
that the author calls forth without providing scientific
documentation. For example, D'Adamo hangs much of his theory on the action
of lectins, proteins found on the surface of
certain foods that can cause various molecules and some types of cells to
stick together. He blames lectins for serious
disruptions throughout the body, from agglutination of the blood cells to
cirrhosis and kidney failure (page 24). He even scares
the reader about these lectin "boogie men" with the tale of ex-KGB agent
Georgie Markov who was murdered with an injection
of the ultra-potent lectin, ricin. Then, on Page 53, D'Adamo states that,
"...certain beans and legumes, especially lentils and
kidney beans, contain lectins that deposit in your muscle tissues, making
them more alkaline and less charged for physical
activity." This is quite a serious scientific charge, and an alarming
thought if you are blood Type O - namely, that after eating a
bowl of bean chili or lentil stew, lectin proteins are depositing in your
muscles and altering their function, changing their acidity,
and diminishing your capability for physical action.
If one is going to make a statement like that - and publish it in a book
destined for the New York Times bestseller list and
intended to change the eating habits of a nation – I believe the author is
obligated to present solid scientific evidence of
supporting their assertions, which D'Adamo repeatedly fails to do. (An
example of an author who presents credible proof is
Dean Ornish, M.D., who published in his book the "before and after"
photographs of X-rays demonstrating increased blood
flow through arteries which had opened more widely after patients had
participated in his diet and lifestyle program.)
If an author is going to frighten millions of Type O readers about eating
kidney beans, lentils, and wheat, I think they are
obligated to provide verifyable evidence. To begin to convince me of the
existence of his “lectin gremlins,” he would have to
publish photographs, taken through a microscope, of muscle tissue biopsied
from people with Type O, Type A, Type B, and
Type AB blood after they have eaten kidney beans and/or lentils. The
photographs should clearly show the lectin deposits in
the muscles of people with Type O blood - and not in the tissue samples from
the muscles of people with Type A blood. If an
author cannot produce proof like this, or clearly cite the scientific
references in the text where other people have demonstrated
such proof, his credibility, to me, is severely diminished. D’Adamo presents
neither photos nor corroborating studies to support
his speculations.
As for the rest of his statement regarding lectins changing the muscles,
"making them more alkaline and less charged for physical
activity," to substantiate that assertion the author would need to publish
or cite studies wherein microelectrodes that measure
acidity inside the cells were inserted into the muscles of people of various
blood types. After they all ate a meal of lentils and
kidney beans, if D'Adamo is to be believed, a significantly greater shift
towards alkalinity should be seen in the muscles of the
Type O subjects. Yet, no such studies are presented. If an author doesn't
have this kind of proof, is it responsible for him to
make statements that may frighten millions of people from eating
high-protein, high-fibre legumes and other potentially valuable
foods? It may indeed be best for a particular person not to eat a
particular legume - but they should do so for solid
nutritional/medical reasons (allergies, colitis, etc.) independent of their
blood type.
What finally pushes the "blood type" theory beyond the limits of
believability for me is the primary mechanism of physiologic
damage that D'Adamo postulates - namely, lectin proteins on some foods
causing blood agglutination in certain people of blood
types who are "not genetically/evolutionarily suited" to eat those foods.
This is a very serious - and potentially life-threatening -
phenomenon that he proposes. Agglutination means that the red cells in your
bloodstream are irreversibly sticking together and
forming clumps. Once they begin to clump together, they don't come apart.
(Note that this is very different than blood sludging,
or so-called rouleoux formation – a phenomenon seen when the surface of the
red cells become coated with fat or other
substances to make them sticky enough to temporarily and reversibly adhere
to each other’s surfaces - but not to become
permanently bonded through irreversible intertwining of surface proteins,
which is what happens in agglutination.) Having your
blood agglutinate as it circulates through your body is not conducive to
good health - or to long term (or short term) survival...
What is so bad about little clumps of red blood cells sailing through the
bloodstream? Red blood cells deliver oxygen to the
cells of vital tissues like the brain, heart and kidneys. To accomplish this
delivery, they must flow through the tiniest of blood
vessels - capillaries so narrow that the red blood cells must line up single
file to get through. If the red cells are being
agglutinated by lectins or anything else, clumps of red cells will clog up
the capillaries and block the blood flow. Thus, the blood
stream will be prevented from delivering its life-sustaining cargo of oxygen
to the tissues served by those capillaries. Cells
deprived of oxygen become damaged, and eventually die (cell death is called
"infarction" of tissue.)
Since most people are unaware of their blood types, let alone what foods are
"evolutionarily inappropriate" for them to eat, it is
reasonable to assume that on most days most people eat the "wrong foods" for
their blood type (e.g., Type O eating wheat,
Type A eating meat, etc.). Thus, according to D'Adamo's theory, most
everyone experiences repeated showers of agglutinated
red cells throughout their bloodstream after most every meal – day after
day, month after month, year after year. If the capillary
beds in your heart, lungs, kidneys, brain, eyes, and other essential organs
are subjected to barrage after barrage of agglutinated
red cells, they will eventually begin to clog up. These micro-areas of
diminished blood flow would at first cause scattered, then
more concentrated areas of tissue damage - with eventually many
micro-infarctions scattered throughout these vital structures.
The brain, heart, lungs, kidneys and adrenals would soon be irreparably
damaged by these processes, resulting in potentially
fatal outcomes in millions of people.
Such a syndrome of organ failures due to lectin-induced micro-infarctions of
the brain, heart, kidneys, retinas, and adrenals
would be well known to pathologists and other medical scientists. It would
not be a subtle disease. In the pathology texts, there
would be clear descriptions - complete with photographs taken through
high-power, optical microscopes as well as electron
microscopes - of damage from lectin deposits and blood agglutination in most
major organ systems. The existence and
intricacies of such a widespread disease would be as common knowledge among
physicians and cell scientists as
atherosclerosis is today. Yet, I am aware of no such descriptions in the
pathologic literature. No pathologist I know has ever
mentioned tissue infarction from lectin-induced red cell agglutination as a
cause of any disease in humans.
So when I read a "one size fits all" statement like on page 63, "Type O's do
not tolerate whole wheat products at all," I have to
ask, "What does he mean, 'at all'?" Do Type O's eat a whole wheat cracker
and fall on the ground holding their abdomen and
vomiting - or worse yet, suffer immediate brain damage due to their blood
cells agglutinating throughout their brain? How much
wheat can a Type O eat before their blood agglutinates? One hamburger bun?
One noodle?
I'm not denying that many people do experience problems when they eat wheat.
They do, but they do so because they have a
true wheat allergy, gluten intolerance, or some other verifyable mechanism -
not because of some sugar and protein molecules
sticking up from the surface of their red blood cells. Like D'Adamo, I grant
that wheat can be a problematic food for people
with colitis, and I often recommend eliminating it from the diet. Lectins
may even play a role in the inflammatory process for
some people. However, before one tells millions of individuals with Type O
blood to never eat whole wheat - many of whom
apparently have no difficulty with whole wheat and who rely on breads as a
major source of energy and protein - isn't some
convincing scientific proof required? I feel that author D'Adamo at least
owes his readers a text citation with supporting
evidence that wheat-induced colon dysfunction is a condition peculiar to
Type O's. Yet, his text is devoid of scientific endnote
citations.
To convince me, he would need to show me photographs of intestinal tissue
from Type O people who have recently eaten
wheat and who clearly have evidence of lectin agglutination clogging up the
function of their intestinal cells. I would also need to
see pictures of tissue biopsies from Types A, B, and AB whose intestinal
walls are seen to be undamaged and far less
burdened with lectin deposits than those with Type O blood. As far as I
know, inflammation of the intestine, like colitis, Crohn's
disease, and gluten sensitivities, occurs in people of all blood groups, not
just Type O - and D'Adamo cites no convincing proof
to the contrary.
Author D’Adamo also makes three hard-to-believe statements concerning dairy
products – two which made me doubt his
understanding of basic science and one that raises concerns about the safety
of his nutritional advice:
1.) D'Adamo states on Page 23 that, "If a person with Type A blood drinks it
(milk), his system will immediately start the
agglutination process in order to reject it." If he wants me to believe a
statement like that, he had best show me pictures of Type
A blood cells under the microscope agglutinating after the person drinks
milk, wherein Type O and Type B blood cells are
shown not to agglutinate. He again shows no such photos or other believable
evidence of the phenomenon. D'Adamo would
also have to explain why Type A people who drink milk (sometimes-massive
quantities of it) do not suffer strokes and emboli
as their blood agglutinates throughout their vascular system. He presents
neither proof nor even plausible explanations
for the above - very troubling in a book presented as "based on science."
2.) On page 151, D’Adamo states that, "...the primary sugar in the Type B
antigen is D-galactosamine, the very same sugar
present in milk." Actually, the primary sugar present in milk is not
D-galactosamine, but rather, lactose. Lactose is a very
different molecule than D-galactosamine, with very different chemical
properties. Even if there were significant amounts of
D-galactosamine in cow's milk, the antibodies in a Type A person's blood
that agglutinate with a Type B person's blood cells
do so by reacting not with D-galactosamine alone, but with a molecule of
D-galactosamine combined with a molecule of the
sugar, fucose, projecting from the surface of the red blood cell. Just
because Type A antibodies will agglutinate with
D-galactosamine+fucose on the surface of a Type B red cell, does not mean
Type A blood will agglutinate with the lactose (or
even free D-galactosamine) in cow's milk. (It is recognized that people of
any blood type may react badly to cow's milk
and other dairy products - for a variety of reasons, but likely not because
lectins in the milk are agglutinating their "wrong" type
blood cells.)
3.) A statement that causes me great concern regarding the safety of
D’Adamo’s dietary advice appears on page 37, where,
despite widespread knowledge that many non-Caucasians are intolerant of
dairy products due to the normal disappearance of
lactase enzymes in their intestinal cells, D'Adamo recommends that "Type B's
of Asian descent may need to incorporate them
(dairy products) more slowly into their diets as they adjust their systems
to them." This seems like strange counsel from an
author trying to improve the intestinal health of his public. I fear that
the consequences for many of his unsuspecting,
lactase-deficient readers who follow such advice will be severe bouts of
abdominal cramps and diarrhea.
Another assertion in this book that make me not want to recommend it to my
patients is on page 53, where D’Adamo writes
that: "This condition, called hypothyroidism, occurs because Type O's tend
not to produce enough iodine." The reality is that
the body does not "produce" iodine at all, any more than it produces
calcium, magnesium, sodium, or any other earth mineral.
Iodine is a halogen element, related to chlorine and bromine, which is taken
up by plants from the soil and in the sea – which
are then consumed in the diet. To worry tens of millions of Type O readers
that they "may not be producing enough iodine"
(which no one does) and are thus at risk for hypothyroidism, is unfounded
and, I feel, unnecessarily worrying. The causes of
clinical hypothyroidism are complex issues, probably involving autoimmune
and other mechanisms of injury to the thyroid tissue.
To imply that eating red meat and avoiding wheat (a "Type O diet") will
help the Type O person "produce iodine" is
unsubstantiated and may not only raise false hopes in the reader, but may
also increase the risk of meat-associated diseases.
Also disturbing is D’Adamo’s portrayal of people of vegetarian persuasion.
Where in the book, he tells flesh-eating Type O's
that they have a "genetic memory of strength, endurance, self-reliance,
daring, intuition, and innate optimism...", "the epitome of
focus, drive...", "hardy and strong, fueled by a high protein diet" (is he
describing a Type O "master race"?), he paints the "more
vegetarian" Type A as submissive tofu eaters, "biologically predisposed to
heart disease, cancer and diabetes" (p. 97).
He paints Type A's with personalities "...poorly suited for the intense,
high-pressured leadership positions at which Type O's
excel" (p.142), stating that, in pressure situations, people with Type A
blood "tend to unravel" and "become anxious and
paranoid, taking everything personally." Finally, on page 143, he saddles
the group with the dark image of Adolph Hitler,
"...a mutated Type A personality." D'Adamo's system seems to create a "blood
type astrology" ("What's your type? O
Positive? I knew it! So am I!") that imposes strange, limiting stereotypes
on very complex human beings.
Remember, there is nothing sacrosanct about the ABO blood typing system
devised by Dr. Landsteiner in the 1920's. It is only
one system classifying more than thirty proteins on the surface of cells
that determine other blood groups, with names like
Auberger, Diego, Duffy, I, Kell, Kidd, Lewis, Lutheran, MNSs, P, Rh, Sutter,
and Xg. This means that food selections that
may be "right" for the ABO blood group system might be "dead wrong" for
someone's Kell or Kidd antigens. Why are we
deifying the D-galactosamine-fucose molecules on the red cell surfaces that
determine ABO Type?
In my opinion, D'Adamo has spun an evolutionary fairy tale that leaves many
unanswered questions. What exactly is he
proposing happened to Type O hunter-gatherers when the Type A people began
growing wheat, barley and other grains? Do
Type O people eat a mouthful of barley and fall down in the dust, unable to
work and reproduce? Do they then become
warlike and club the agrarian people to death because lectins are clogging
their intestines? Do the genetic changes to Type A
blood type magically appear just before a society grows new grains (allowing
them to eat the new grains in the first place), or
did Type A blood types emerge after the grains are grown, as the people with
Type O blood died out from their blood
agglutinating in their brains? And why would so many of the native Indians
of North America, classic Type O hunters, go to the
trouble of cultivating high-lectin corn (maize)? Someone talk some science
to me, please...
Is the blood type the ultimate determinant of successful adaptation to a
particular dietary style? How do we explain the
experience of people who say, "I tried to be a vegetarian and it didn't work
for me - so I added some meat back into my diet
and I feel better. I guess I'm a Type O caveman," or "A practitioner of
'live cell' analysis stuck my finger and I saw my blood
agglutinate! He said I must have eaten foods wrong for my blood type!" I
hear variations of these two statements several times
per year. Do either of these phenomena validate D'Adamo's blood type theory?
First, the red cell clumping on the TV screen... I have walked through many
medical meetings and health expos and seen this
demonstration set up and performed many times. A subject's finger is
punctured and a drop of their blood is placed under the
microscope slide with the image projected on a large screen or television
monitor. The results can appear quite dramatic as a
person often sees on the TV screen their red blood cells, platelets, and
other cellular elements apparently misshapen and
clumped together. It can then be an opportune time to convince the startled
person that their blood is laden with toxins or
deficient in vital minerals or some other nutrient - and then sell them the
"necessary" supplements that the "live cell analyst"
happens to be purveying.
Though the images may be graphically convincing, the unsuspecting subject is
probably unaware that they may have just
witnessed a biological parlor trick. The "live cell analyst" has probably
failed to inform them that the "agglutinating" effect seen
on the screen can be produced by a number of factors, most having nothing to
do with lectins, blood type, or any other forces
beyond the physics and chemistry of a drop of blood on a slide. Remember,
that a drop of blood on the microscope slide is
very different than a drop of blood flowing through your bloodstream.
While flowing naturally through the bloodstream within the arteries and
veins, the blood is shielded from light, is held at a
constant temperature of 98.6 F., is under much higher pressure than room
air, and is physically moving very rapidly through the
"piping" system of blood vessels. These are all factors which profoundly
affect the surface characteristics of the red blood cells,
making them less likely to stick together. The red cells’ rapid motion
through the bloodstream also prevents antibody fixation,
blood clotting factor activation, and other pro-agglutinating forces from
exerting much effect. When the drop of blood
is squeezed out onto the microscope slide, all these factors are changed or
eliminated. At that point, physical forces - cooler
temperatures, lower pressure, exposure to light, physical stagnation,
activation of enzyme systems, etc. - begin to affect the
blood on the slide in ways that may make it much more likely that the cells
may begin to clump together - independent of blood
type or presence of lectins.
In addition to the above purely physical influences, other chemical factors
may be at work on the slide to create the appearance
of clumping - independent of the person's blood group. These chemical agents
include:
1. The person's last meal. In particular, the fats from the egg yolk at
breakfast or the olive oil in the salad dressing at lunch may
be invisibly coating the red blood cells, making them stickier and more
likely to adhere together. Fats will make red blood cells
of all blood types sticky and more likely to clump together. In my
experience, "live cell analysts" seldom ask the subject about
their last meal nor analyze it for the fat content.
2. Antibodies (immune proteins that can bind to cells) left over from a
recent viral infection or allergic reaction - but not
associated with food lectins - can coat red blood cells and make them prone
to clump together.
3. Molecules with unknown chemical properties, introduced into our blood
from living in the “civilized world” - such as food
colorings, food preservatives like BHT (butylated hydroxytoluene),
hydrogenated oils eaten in fast foods, snacks, and
restaurant meals, as well as birth control pills, aspirin, cold medications,
and over-the-counter remedies, etc. - may affect
the tendency of blood cells to clump, independent of lectins or blood type.
4. The acidity (pH) of the blood, the levels of calcium, sodium, and other
circulating minerals - even the concentration of salt in
the “saline solution” that the “live cell analyst” mixes with the drop of
blood - can all dramatically affect its behavior and
appearance on the slide. Add to this the effects of exercise, medications,
even a prolonged time since the last drink of water –
it’s no wonder the blood on the slide might look strange. There are
hundreds of unseen forces acting upon the red blood cells,
platelets, and suspended plasma proteins.
Under some conditions, the blood cells of some individuals might even tend
to clump together when viewed on the television
screen. However, this does not mean that individual is ill, suffering from a
nutritional deficiency, or is being agglutinated
internally from the lectins in their diet. Unfortunately, this is often not
the message they receive from the “live cell analyst”about
to make a recommendation as to which one of their proprietary supplements to
buy in order to remedy the “condition.”
(This is not to imply that all people performing “live cell analysis” are
unscrupulous, but only that the technology creates a
powerful imagery and it is easy to abuse. There seems to be quite a number
of people demonstrating the televised technique for
the public who are unaware of the subtleties of the blood stream and the
body - and thus not qualified to make clinical
diagnoses based upon what they are seeing on the TV monitor. Yet, it is very
easy for “a live cell analyst “ - for reasons
altruistic, capitalistic, or otherwise – to issue an ominous-sounding term
or diagnosis to an unsuspecting member of the public. I
have had several people consult me, worried that their blood was
agglutinating inside their arteries, or that their “immune
system was shot,” based upon comments made at a health expo by a “live cell
analyst” - who had received little more than a
weekend training course. The public should be made aware of the limitations
of the “live cell analysis” technique, so they are
not unduly frightened by what they may see on the screen or hear from the
analyst.)
What of the people who say they feel better when they resumed flesh eating
after intervals of consuming vegetarian or vegan
diets? Unquestionably, their experiences have some important messages for
us. But what are they? Here are some
possibilities...
It is known that, in some people, merely adjusting the proportions of
proteins, fats and sugars in any manner significantly new to
their body can produce noticeable improvements in the way they feel.
Changing the proportion of raw vs. cooked foods can
similarly have beneficial effects. Some people who feel that their health
has improved after adopting a "zone" or "blood type"
diet may actually be benefiting from just eating less carbohydrates, more
protein, etc. We plan to investigate whether some of
the individuals who re-introduced animal products into their diet could have
achieved similar effects by altering their selection
and quantities of plant-based foods.
We recognize that there are significant metabolic differences between
people. It may well be that some of these differences may
propel certain individuals towards flesh consumption. It may be, however,
that the cause is not so much genetic, as acquired
after birth. Remember, virtually every person who reports adding meat back
into a previously vegetarian diet is an individual
who was raised on a meat-based diet.
Why is this important? The kind of foods one eats in their early years may
set biochemical patterns that last for a lifetime. For
example, the human body can synthesize from simpler molecules some essential
substances like carnitine (required for energy
production) and some long-chain fatty acids (EPA, DHA, etc., needed for
hormone function, membrane synthesis, etc.).
People who eat meat ingest these substances, pre-formed, in the muscles and
other animal tissues they consume. It may be that
the body of a person raised as a life-long omnivore becomes functionally
dependent upon a diet that contains these pre-formed
nutrients. As adults, if they suddenly change to a completely plant-based
style of eating, where the foods are essentially devoid
of pre-formed carnitine, EPA, DHA, etc., they may find themselves in a body
with enzyme systems unable to synthesize all the
energy-generating compounds, fatty acids, and other molecules they may
require.
After months or years on a flesh-free diet, these individuals might
experience deterioration of their health or energy - only to feel
better upon resumption of meat ingestion. To the person, this may seem like
confirmation that they are "natural meat eaters."
Rather, it may be evidence of an acquired dependency on flesh-borne
nutrients formed through early eating patterns. If this is
the case, it may be possible to prevent, repair, or at least compensate for
these imbalances through provision of additional
nutrients, removal of inhibiting substances in the diet, varying
combinations of food, etc., utilizing foods of plant-based origin.
There is much to learn about the subject and much research needs to be done.
In my experience, these problems are not encountered in people raised on
vegetarian diets from infancy. This effect might be
especially pronounced in long-term omnivores who make an abrupt change to a
vegan diet, as opposed to those who taper
flesh foods out of their diet more gradually. It may be that some
“omnivore-from-birth” people who desire to sustain themselves
on a vegan diet may have to make a more graded transition to completely
plant-based foods, sometimes over several weeks or
months, to give the body time to "gear up" its metabolic machinery. In other
words, what appears to be a “natural need for
meat” may really be the need for an attenuated weaning process from animal
products in order to overcome
metabolic patterns begun early in life, created largely by cultural
practices.
Through the Institute of Education and Research, we plan to study these
phenomena in detail and will attempt to identify any
nutrients that may be required in larger amounts when consuming vegetarian
diets. A goal of our research is to develop
science-based guidelines to aid anyone who chooses to nourish their body on
exclusively plant-based foods to do so with
optimal benefits to their health and well being.
An additional thought: Less than optimal function on a plant-based diet (or
any diet) may not stem from a “lack of meat” or a
nutrient deficiency at all, but rather from an individual’s other health
conditions, like digestive dysfunction, malabsorption by the
intestine, parasite problems, adverse immune reactions, etc. To me, these
are far more likely mechanisms that could explain the
“failure-to-thrive” syndrome occasionally seen in vegetarians and vegans -
rather than a genetic mandate to consume flesh
determined by their blood type. Much more research is needed to obtain the
answers to so many questions in this essential but
subtle science.
Beyond the “blood type issue,” perhaps a deeper question about any book
which advocates a meat-based diet for the majority
of the population is, "In today's world, is eating meat, in any form, safe?"
It appears that to base one's diet around animal foods
is becoming a high-risk activity, similar to unsafe sex or driving without
wearing a seat belt. Consider the smorgasbord of health
hazards available at today's meat counters… It’s a safe bet that virtually
every cut of "fresh" meat produced commercially in
North America today contains:
Residues of hydrocarbon pesticides and herbicides, linked to cancers and
birth defects,
Residues of antibiotics and growth-augmenting sex hormones fed to the
animals and stored in their tissues,
Fecal microbes, like the potentially lethal E. coli 0:157 and Salmonella
bacteria. (Hamburger roulette, anyone?)
The nightmare specter of the brain-destroying prion protein, the cause of
spongioform encephalopathies - "mad cow disease" in
bovines - Creutzfeldt-Jacob disease, or CJD in humans. (I feel sadly certain
that what occurred in England with mad cow
disease will probably occur here in North America and other parts of the
world within in the next two years. I sincerely hope
I'm wrong.)
Given these ever-increasing risks connected to meat consumption, I fear that
the theories and books that attempt to justify and
promote the eating of flesh - for whatever reason - could be opening the
floodgates of ghastly epidemics five or ten years from
now. These plagues likely will have a magnitude that will dwarf everybody's
concerns about "being in the zone" or eating "right
for your type."
Finally, no matter what advocates of animal-based diets might say about the
merits of being in the "zone" or "eating right for
your blood type," from an ecological standpoint, a meat-based diet for the
world's population is non-achievable and, for even a
sizeable minority, is non-sustainable. The world’s soils, waters, and
forests are being decimated to produce meat-based diets.
We are destroying the life support systems of our planet - of our
children's planet - for a mouthful of flesh. To me, the
promotion of diets centered around meat increases the chances of ecological
catastrophes and thus jeopardizes each of our
futures.
I wish for everyone optimal health, happiness, and longevity. We owe it to
ourselves, to our children, and to all who come after
them, to see how optimal function and life span can be achieved on diets
that are truly sustainable - for individuals, for societies,
and for the planet. It is, after all, the food of all our futures.
EJ
by John Weisberger, PhD
Over the past 50 years we have learned much about how diet affects cancer risk.
If Americans adopted the current dietary
guidelines issued by the National Cancer Institute, cancer rates would decrease
by as much as 25 to 50%. Plant foods are
protective for several reasons.
Fiber Reduces Cancer Risk
Early interest in fiber and cancer came from intriguing observations of the
Finnish population (1). The people in Finland have
one of the highest rates of heart attacks, but they have relatively low rates of
both colon and breast cancer. Dietary studies
showed that the Finns are high consumers of dairy products including milk, which
may contribute to their high rate of heart
disease. However, they also consume a type of rye bread high in bran fiber. When
investigators studied stool samples of Finns
and compared them to those of people living in New York (the researchers
collected and studied stool specimens from 40
individuals from each country) they found that stools of Finns weighed two to
three times more than those of New Yorkers.
Also, the concentration of bile acids in Finnish stools was much lower than that
in the American stools. Bile acids are
compounds produced by the liver to aid in the digestion of fats but they also
appear to promote the growth of cancer cells in
the colon.
The larger stool also increases the excretion of estrogen and therefore could
result in lower blood estrogen levels in Finnish
women. This may protect against breast cancer, since lower estrogen levels are
associated with reduced risk for breast cancer.
About the same time that the Finns were being studied, Dr. Denis Burkitt, a
distinguished British surgeon stationed in Uganda,
noted that colon cancer rates were high among British living in Africa but rare
among native Africans (2). In fact, the Africans
rarely had any intestinal diseases such as appendicitis, diverticulosis, and
irritable bowel syndrome. Dr. Burkitt found that,
compared to the British, the Africans ate more high-fiber cereals and lots of
fruits and vegetables--a fiber intake as high as 70
grams a day compared to 15 grams per day which is common intake among
westerners. They generated multiple stools every
day, weighing as much as 10 to 15 ounces.
Fiber helps to reduce colon cancer in two ways. Bran cereals and high fiber
breads contain mostly insoluble fiber, which
absorbs fluid and swells up to provide for increased stool bulk. This helps to
decrease the concentration of harmful bile acids
and other potential carcinogens in the stool. Oat bran and many vegetables
contain mostly soluble fiber. This doesn't add much
to stool bulk but forms a gel-like matrix that aids in the elimination of bile
acids and other potentially harmful components in the
colon.
Fiber is extremely important in reducing risk for colon cancer. In 1978, when
the Food and Drug Administration (FDA)
initiated a ban on the artificial sweetener saccharin, I noted that the American
people would be better off if the FDA banned
white bread (3).
In view of what we know about fiber and cancer risk, it is indeed important to
consume a diet high in cereals, whole grain
breads, fruits and vegetables.
Phytochemicals and Antioxidants: The Power of a Fruit and Vegetable Diet
International comparisons and comparisons within countries show that people who
eat green and yellow vegetables and fruits
have a lower incidence of major chronic disease, including many types of cancer.
More than 200 studies show the benefits of
fruits and vegetables. The immediate thought that comes to mind is that
vegetables and fruits are good sources of vitamins and
minerals (4).
However, vegetables and fruits contribute much more to good health than just
vitamins. They are sources of phytochemicals-or
plant chemicals-which are not nutrients, but are biologically active compounds.
Just as humans produce antibodies to ward off
infection, phytochemicals offer protection to plants. They may also be
protective for us (5,6).
There are many different types of phytochemicals in plant foods. These include
indoles in vegetables of the cabbage family,
sulfur compounds in garlic and leeks, isoflavones (plant estrogens) in soybeans,
lignans in flax seed, and carotenoids in
many vegetables. Phytochemicals appear to exert physiological effects in many
different ways (7). They may stimulate the
immune system, help to detoxify harmful chemicals, affect hormone levels, and
control cell growth. But of particular importance
is the action of some phytochemicals as antioxidants.
Why is this significant? Living cells require oxygen because the enzymes that
generate the energy essential to cell functioning
require oxygen. But during the process of oxygen use, cells can also generate
abnormal reactive chemicals. Some of these
reactive oxygen components are potentially dangerous and may lead to heart
disease or initiate cancer. Nature has provided
for neutralization of these potentially harmful components by supplying
antioxidants in food and drink.
Some Fats Raise Cancer Risk
As long ago as the 1940s, a few early pioneers suggested that dietary fat played
a role in enhancing cancer risk. However, their
research was not considered "fashionable" by mainstream cancer researchers and
was largely ignored until the mid-1960s. At
that time, Canadian researcher Kenneth Carroll showed that laboratory animals
fed a 40% fat diet (similar to what westerners
eat) had a much higher rate of breast cancer compared to those fed a 10% fat
diet (8). Later research at the American Health
Foundation (AHF) in New York confirmed these findings.
The studies at the AHF were inspired by the dramatic differences in breast
cancer rates between women in the United States,
whose fat intake averaged about 40%, and those in Japan, whose fat intake was
closer to 10%. But women in Italy also had
relatively lower cancer rates despite a fairly high fat intake. This gave rise
to questions about type of fat as well as amount of fat
in the diet (9).
Further studies showed that high intakes of animal fat and of polyunsaturated
oils like corn or safflower oil increased the
number of breast and colon tumors, compared to low-fat intake. A high dose of
corn oil, for example, led to increased
synthesis of bile acids, the compounds that raise risk for colon cancer.
Other types of fat had different effects, however. The omega-3 fatty acids found
in fish oils and some plant foods actually
reduced the incidence of breast and colon tumors, while monounsaturated oils
such as olive oil were neutral. Although it hasn't
been tested, canola oil, which is high in monounsaturated oil and contains some
omega-3s, is likely a lower risk oil than other
vegetable oils. The same may be true of flax seed oil, which is high in omega-3
fats. Both monounsaturated and omega-3 fats
may also protect against heart disease. This would help to explain the lower
rates of both cancer and heart disease in southern
Italy and Greece (10). Even though these diets are relatively high in total fat,
much of the fat in the cuisines of these countries is
monounsaturated or rich in omega-3 fatty acids.
Other Food Components May Raise Cancer Risk
Cooking meat to the well-done stage involves the generation of reactive
chemicals called heterocyclic amines. These chemicals,
formed during browning of meat, may increase the risk of cancer of the colon,
breast, prostate, and pancreas. Red meat
appears to be particularly harmful (11).
The use of salt and pickled foods, common in many types of Asian cuisine, raises
risk for stomach and esophageal cancer (12).
Conclusion
Early humans consumed foods that were freely available from nature-wild fruits,
berries, greens, seeds, and roots. They may
have used some milk from lactating animals but ate little meat. In modern times,
many cultures have adopted a
meat-and-potatoes diet with excessive amounts of salt.
Scientific research has produced a sound basis of knowledge for producing
guidelines for a healthy lifestyle in order to reduce
risk for cancer (13, 14). Western eating habits are based on the wrong foods-too
much of the wrong kinds of fat, too much
meat with dangerous heterocyclic amines, too many salted foods, too little
dietary fiber, and too few fruits and vegetables.
Healthier eating habits should include generous use of fruits and vegetables-5
to 10 servings a day should be a goal, and foods
such as cooked tomatoes and soy products should be used frequently. Foods high
in fiber such as cereals, whole grain breads,
and legumes should also be a regular part of the diet. And, choosing sources of
monounsaturated fat and omega-3 fatty acids
over animal fats and other plant fats should be a goal. Here at the American
Health Foundation, our research goal is to "allow
us to die young as late as possible."
1.Cancer, 42:2832, 1978.
2.J Nutrition, 124:1551, 1994.
3.IARC Scientific Publications, 139:61, 1996.
4.Nutrition Cancer, 26:123, 1996.
5.Environmental Health Perspectives, 7:103, 1995.
6.J Nutrition, 125:567, 1995.
7.Cancer Research, 35:3231, 1975.
8.J Am Diet Assoc, 97:5, 1996.
9.J Nat Cancer Inst, 87:110, 1995.
10.Europ J Cancer Prevention, 5 (Suppl 2):1, 1996.
11.Chem Res Toxicol, 9:58, 1996.
12.Cancer Letters, 114:1, 1997.
13.Clinical Oncology, 10, 1995.
Dr. John Weisburger has conducted research on prevention and cancer and has
published over 500 papers. He is a past
Director of the Research Institute of the American Health Foundation in
Valhalla, New York.
Pete Beyer
EJ wrote:
Good post-- but a message about food and not supplements, toxins or
conspiracies???
my, my what's sci med nutr coming to? Pete B. :-)>
Just a question-- I've followed Weisburger's writings for many years-- Is the
conclusion also his? also there are 14 references shown in the text but 13 in the
list-- is that one missing in the list?
David Lloyd-Jones
EJ wrote in message <362247EC...@puc.edu>...
>
>The “blood type diet” theory has gained widespread attention from the
public
>since the release of “Eat Right For Your Type”
>by Peter J. D’Adamo, N. D. (G. P. Putnam’s Sons, New York, 1996). The
book's
>basic premise - that Type O's are the
>dominant, hunter-caveman type that require meat in the diet, that Type A's
>are docile vegetarians, while Type B's are
>dairy-eating omnivores - has become a manifesto for many people to
>rationalize including regular portions of meat and other
>animal products in their diet. ("After all, my ancestors did it.")
>However, the "blood type diet" theory, and the book that
>promotes it, presents many problems that prevent me from seriously basing
>any of my dietary choices upon them.
>
You're right about the problems: who's going to take seriously a simple
three-way division of everybody that doesn't even take birth date and sun
sign into account? What America is clearly waiting for is an astrological
blood-type diet.
-dlj.