We have heard people say, “Watch out for
soy.” “Soy will cause this, that, and the other thing,” and “If you are eating
soy, you will have some very bad things happen to you.” There are some websites
that give information that sounds very good, causing people to wonder about soy
and soy products.
Most of the negative allegations ultimately
come from one or two sources, and are written by four people who are very
anti-soy. At least two of these people have PhD degrees, which lends
credibility to their claims. But let’s look at some of their allegations.
1. Accusation: Soy causes infertility.
Soy has been used for centuries in the East.
However, neither China nor Japan has a fertility problem and are very well
populated though they have used soy for centuries.
Experiments were performed on female
cheetahs. When they were fed high concentrations of genistein
and daidzein, they had problems conceiving. One must
note that cheetahs are cats that have different digestive systems than humans
and they are also sensitive to these substances. We need to be cautious of
studies that are based on high concentrations of a substance, which more than
likely exceeds the amount that a person would normally eat.
In another experiment, one to five-day-old
rats were injected with genistein. Later in life they
had fewer pregnancies and some became infertile. There is a danger of using
animal studies for determining what is good or bad for humans. Humans do not
inject their food but ingest it, making these experiments to show doubtful
similarities in outcome.
Let’s look at some examples of this,
particularly in drug testing, because animals are used extensively.
Many drugs which tested safe in animals, later had to be recalled because of the dangerous
results in humans.
Vioxx is a pain killer and
it was safely tested on animals—rats, mice, monkeys and dogs. It tested safe
and was even heart protective. But in humans it causes congestive heart
failure, strokes and heart attacks.
Rezulin is a diabetes drug,
which tested safe on animals but in humans it can cause liver failure.
Zomax is another pain
medicine that tested safe on animals but had a deadly effect on humans.
Fen-phen was a weight loss drug, and it tested safe on animals,
but in humans, caused thickening of the heart valves.
Thalidomide was widely tested on
animals with total safety but with horrendous birth defects in children whose
mothers took it for morning sickness.
Opren tested good on
monkeys but killed 61 people.
Cylert was fine for animals
but caused liver failure in hyperactive children.
Tobacco. For years animal
tests were inconclusive, so the tobacco companies used that to their advantage
and promoted their products. We now know, with very great clarity, that tobacco
is one of the most potent detractors from health and a great promoter of cancer
Other examples prove that animals are not
necessarily the best for determining what is good or bad for humans. Ninety
percent of the drugs that tested safe in animals failed human trial, and some
are exactly opposite. An example of the opposite is penicillin. When it was
first developed it was tried on rabbits and seen to be completely ineffective.
It was a full decade later before it was used as an antibiotic in humans,
because it failed the rabbit trials. Looking at animals to see what is good for
humans is not necessarily the best thing, unless it can be backed up with real
human trials and tests. Animal testing has proven to be quite unreliable and
according to the soy testing, we are seeing one thing for people in populations
using soy compared to cheetahs.
Eggs are considered the perfect source of
protein because of rat studies. Young rats grew faster, but we were not told by
the proponents of the egg industry that those were the rats that died sooner.
Baby rats failed to thrive on soy; however, they also failed to thrive on human
breast milk. Are we to say that baby rats are a good example for determining
what is good for humans? Are we to say that human breast milk is bad for
babies? Obviously not! Then we cannot take that same study and say soy should
not be used on humans.
Animal biology is physiologically and
anatomically different from humans; therefore animal studies can be very
misleading. Human trials are much more reliable looking at the different populations
that use soy versus those not using it. Those using soy typically have a better
health status than western society and the diet often includes greater amounts
of plant foods, especially leafy greens, and it has been found that the use of
soy products did not detract from their overall health.
In reality, since virtually all of the
accusations against soy are based upon animal studies and not humans, at best
they can be meaningless and at worst they can be totally misleading and take
you completely onto the wrong track and some wrong conclusions.
It is said that soy causes reproductive
problems. One study reported that the declining male fertility in the last 60
years was blamed on estrogens, chemicals, plastics and tofu. The one thing they
do not address is the estrogens that are fed to livestock for fattening. The phyto estrogens in tofu are very weak in estrogen activity,
especially as compared to the potent estrogens that are fed to the livestock.
Soy has only become popular in the western
world in the last twenty years or so. But here we have these studies going back
50 or 60 years before soy became popular.
We have also seen that when people, who have
not been able to conceive, switch to a plant based diet, including tofu and soy
products, they improve their chance of having children.
In one study men were administered doses of
up to 30 times more than normal. First of all, 30 times
more of what? It is not clear. Was it 30 times more of estrogen or tofu?
Instead of eating one slice of tofu, was it 30 slices of tofu every day? Was it
the isoflavones? The study is unclear. It would be
unrealistic for anyone to eat 30 slices of tofu in a day, but that anti-soy
conclusion was that the 30 times of whatever will lead to a drop in
testosterone and then also it will cause some men to become demasculinized.
Then the question is asked in a very calm, serious tone, “Do you want to become
demasculinized”? No male would want that, but by the
emotionally charged words they fail to realize that this is not a realistic
situation and there is not a lot of real solid evidence behind the claim.
Another study seemed to indicate that there
was an increased risk of infant male development. This was a small study in
which they also failed to mention that mothers who had iron supplements during
their pregnancies, or had the flu during their trimester, also had a heightened
risk of that same abnormal male infant development. There is a lot of muddied
water, and blame cannot be pinned only on soy.
Another claim is made that soy causes
significant biological effects in women, and it is put in such a way that the
significant biological effects are on the negative side. However, there are
some that show that lengthening the cycle, which is what happens, actually ends
up being protective against breast cancer—it correlates with a reduced risk of
We do not see the accusations of the anti-soy
people playing out in real life. We do not see the infertility problems being a
problem for humans. Whether or not it is in China, or people who are now
switching to vegetarian from a meat diet, these things are based upon bad
analysis and ridiculous dosages such as 30 times more than “what”; unreliable
studies that are very small and isolated, as well as creating a negative slant
on something that is positive. These are some of the problems with the
2. Accusation: Soy raises the risk of
cancer and other diseases.
There are isoflavones
in the soy that are called genistein and daidzein. These are phyto
estrogens. This is pretty much what this whole concept is based upon and that
high estrogen levels will promote cancer. It is true that estrogen tells the
cells to hurry up and multiply, and they fail to develop properly many times;
that translates very easily into cancer. We looked at the fact that the meat
industry feeds the animals estrogens to make them develop and to get fat
quickly. The phyto estrogens in this are very weak in
this action. In fact, some researchers believe that instead of their being a
problem, they actually bind to the estrogen receptor sights and lock the
receptor sites from the more potent estrogen. Therefore, they are actually
being protected against breast cancer. They find this to be the case especially
when the soy consumption has begun early in life as a young girl.
The anti-soy people use this as the basis for
many accusations against soy and breast cancer when other studies do not
indicate that soy increases breast cancer risk. Again, the focus is not on the
fact that we get estrogens from the meat and dairy industry as well. Obviously,
we do need some estrogen but we do not need a high or potent source physically.
We do not want to stop eating tofu because it
is uncertain whether or not isolated substances may cause a harmful effect. We
do not recommend mega doses of isoflavones. We want
the full package as opposed to pulling out the isoflavones
and giving that in concentrated or very large amounts.
It is claimed that protease inhibitors from
soy increases risk of pancreatic cancer in rats and chicks. It is interesting
that they look at rats and chicks and don’t seem to pay much attention to the
fact that this does not happen in mice, dogs, pigs, monkeys or humans. So,
apparently rats and chicks are extraordinarily sensitive to these inhibitors.
When rats and chicks are fed nothing but soy, they do have an increased risk of
pancreatic cancer. That is not the same with the other groups we have mentioned
It is also interesting that these protease
inhibitors and other enzyme inhibitors are rendered basically irrelevant when
the soy is made into tofu or soy milk, tempeh and so
forth. Protease inhibitors inhibit the absorption of protein. They use that
point also. But protein is so high in tofu and related products that it is
really a non-issue.
The populations that use soy have a reduced
risk of pancreatic cancer and other cancers.
The anti-soy people unfortunately have a
difficult time accepting the fact that different species of creatures,
including humans, act differently and process soy differently. It is also
interesting that they ignore the fact the protease inhibitors have been shown
in some studies to inhibit colon, prostate and breast cancer in humans. Some
are constantly looking at a negative slant and not looking at the whole
3. Accusation: Soy shrinks brains and
causes Alzheimer’s—Soy reduces cognitive function.
This accusation was based on one isolated
study in Hawaii in which Japanese American men who ate tofu in their middle age
had the greatest mental deterioration and dementia as seniors. This was based
upon one study, and it is not a good idea to base our theories on one study. A
physician found that the tofu these individuals were eating contained an
extra-ordinary ordinary amount of aluminum. That gives us an idea of the real
culprit as opposed to tofu. Again, we do not see this happening in the East or
in other countries with men becoming demented or deteriorating mentally as they
Other studies put children on a vegetarian
diet with tofu and it boosted their grades and their energy. These were
children who were having low grades and not performing well academically. After
a vegan diet for a month that included tofu, they reported that the children
showed improvement in both the classroom and on the basketball court. Some
grade point averages (GPA) rose from 1.6 to 3.4. Others ranged from a 3.1 to a
3.9; that is from a B average to an A average. All scored at least an 85
percent on their final exam.
Does soy decrease cognizant
function? Apparently not. Does soy cause cancer? Not
that we can see. Does soy cause infertility? None of these symptoms have been
proven in the practicalities of life.
4. Accusation: Soy interferes with thyroid
and causes goiter.
Soy contains goitrogens,
which is considered another anti-nutrient that suppresses thyroid function.
This only happens when iodine intake is low. It is very interesting that other
foods that contain goitrogens are cruciferous
vegetables. Cruciferous vegetables are noted for cancer prevention. These
include cabbage, cauliflower, broccoli and Brussels sprouts; also sweet
potatoes, lima beans and millet.
If we say that it is necessary to eliminate
the foods that contain goitrogens, it will also be
necessary to eliminate the cruciferous vegetables along with sweet potatoes,
lima beans and millet. Of course, this is not recommended; the focus is only on
The focus should not be on one particular
substance in a food. In most common vegetables, you could find a potentially
toxic or harmful nutrient that if isolated and concentrated and fed to humans,
it would have some undesirable side effects.
5. Accusation: Soy causes osteoporosis.
This is also totally unfounded. There is a
strong correlation between the amount of animal foods in a diet and the
strength of the bones. Studies show that the countries that use the animal
products actually have a higher incidence of osteoporosis compared to cultures
that use the plant food. This also includes the Chinese, Japanese and other
Eastern people. The more plant food consumed, the stronger the bones.
Anti-soy people say that soy causes vitamin D
deficiency and the high rate of osteoporosis is because of vitamin D depletion
or because of it not being in the diet because of substituting soy oil instead
of butter. So the butter people are using soy oil and they say that is a
problem because they put vitamin D in butter. Actually sunshine is a better
source of vitamin D than getting it through butter that has been supplemented.
Our skin makes vitamin D from sunlight. Sunlight is one of the eight natural
Calcium from soy is nearly as bio-available
as calcium from cow’s milk. Often the issue is how bio-available is a
particular plant food when compared to meat—whether it is calcium, iron, or
other nutrients. It is quite often not as straightforward as it is purported to
be. It is actually good that the iron in the plant food is not as absorbable as
it is in animal food, because it has been noted that high levels of iron for
some people can increase their risk of heart disease. It is good to have checks
and balances. Just because something is inhibited does not mean that the
inhibition is bad; it may just put the brakes on something.
Calcium is usually a point of concern or
controversy. Magnesium is just as important for body health and bones as
calcium. Greens are an important source of calcium and magnesium. Other good
sources of calcium are almonds, sesame seeds and tofu.
6. Accusation: Soy causes zinc deficiency
because of the phytates.
In large quantities phytates
can block absorption, and they particularly focus on zinc. Phytates
can block the absorption of several different minerals, and again the brakes
are not necessarily a bad thing. The anti-soy people say that the safety
feeling that vegetarians get is because of zinc deficiency, and they interpret
that as being a high spiritual development. This is wrong. There is absolutely
no proof that because of a zinc deficiency you enjoy spiritual things.
Soaking, roasting, sprouting, baking and
leavening increased the bio-availability of minerals. Virtually any time you
use soy, one of these things would have happened to it. Even if you are using
just plain soybeans as a legume, you will have had to soak and boil them. If
you are going to make tofu, you certainly would have soaked them at some point
in time. Any time you use soybeans it will have included one of these
processes. This applies to all of the phytates in the
different vegetarian foods, including wheat. Wheat has been known to have phytates as well. We hear people say that vegetarians have
to be careful that they do not have mineral deficiencies because of the phytates. Well, when you make bread, you are certainly
baking, to make these minerals more bio-available. A healthy vegetarian diet is
rich in nutrients by getting a good representation in of fruits, nuts, legumes,
vegetables and whole grains.
Zinc deficiency is no more common in
vegetarians compared to non-vegetarians and should not be singled out.
Some phytates act
as potent antioxidants and favorably regulate cell growth. It is interesting
that even though phytates have been promoted as being
a problem, other studies show that they actually act as antioxidants. They are
not necessarily a bad thing and they regulate cell growth. This could possibly
put the brakes on the quick development of cancer cells and cells that are
developing too quickly, slowing them down so they have time to mature and do
what they need to do. Instead of being bad, phytates
in the end could be very positive for us, particularly when we get them from
the whole plant.
7. Accusation: Soy contains toxins and
We have already talked about phytates being antioxidants and actually helping to keep
things in balance as far as cell development. We can also reference that to
mineral absorption as well.
Many plant foods contain substances in
concentration and isolation that would produce unwanted effects. All of the
plant foods have some potential toxins in them. The following are some
Broccoli, lentils and grapefruit contain
naturally occurring pesticides, which could cause mutation. If we took certain
substances in these plant foods, isolated them, concentrated them, made a very
potent dosage out of them, we would have problems.
Peanuts and peanut butter contain aflotoxins that could cause cancer.
Celery contains toxins that could damage the
immune system and cause photosensitivities. Are we
telling people not to eat celery? No. Celery is very good and also contains
organic sodium, which can be very good, especially in the hot summertime.
Spinach and chard contain oxalic acid that
binds with calcium and diminishes absorption. Again, we are not telling people
to stop eating spinach because of this.
In eating normal quantities of these foods,
these things are not a problem. But the anti-soy people ignore that the isolated,
compounded high levels of some of these things may cause problems.
summary of what the anti-soy people do:
rely upon animal studies that are not applicable to humans.
use small or isolated studies that are not supported by the bulk of the
use examples of extreme intakes of soy.
look at just certain components of soy that you would have to use in very high
quantities isolated for it to be called a problem. This is not, in reality, how
we use our soy.
focus on naturally occurring substances that, in isolation, would cause
undesirable side effects.
benefits of soy are as follows:
studies have shown that soy, in conjunction with a healthy diet, lowers risk of
has nine times less saturated fat as compared to cow’s milk.
is cholesterol free, lowers total and LDL cholesterol. Interestingly, some
anti-soy people say that lowering your cholesterol results in a greater number
of deaths. Their proof is an article
that they wrote themselves. This is totally unsupported by the scientific
show that soy contributes to the reduction of cancer.
contains many phyto chemicals, which protect against
may reduce insulin resistance, renal damage and fatty liver in diabetics. For
people who are on insulin, switching from animal protein to plant protein can
be very helpful. Part of that protein can be soy. Also, people who have renal
failure need to bring down their protein, so switching them from animal protein
to plant protein, including soy, can be very healthful.
guidelines for eating soy:
Eat a plant-based diet, not a soy based diet. Eating soy at every meal is too
much and goes against the principle of temperance. Some people believe they do
not get enough protein; however, a plant-based diet will provide all of the
protein needed from the different whole grains and legumes with some tofu or
soy, and you will be just fine. You would virtually have to live on sweet
potatoes and apples for the rest of your life in order to have a protein
deficiency on a vegetarian diet. Eating a varied diet with enough calories to
maintain proper body weight will give you enough protein. It is not essential
to have soy in your diet, but the versatility of soy and the extra protein that
it does provide are actually a benefit to the plant-based diet.
the intake of soy to two to three servings a day. Asians typically eat from one
to three servings of soy per day. From looking at their population, they are
doing quite well on that. Most vegetarian nutritionists will say to limit your
consumption of soy to two to three servings a day.
Serving size. A serving is approximately three to four
ounces of tofu, which is about one-fourth of a block of tofu, or one cup of
soymilk. There are some days you might have a little extra, and some days you
may not have any, but the average is no more than two or three servings per
whole soy foods such as tofu, soymilk, soy nuts rather than protein isolates. This goes back to
the concept that whole foods are better than refined foods, just like we choose
whole wheat bread instead of white bread. The whole food is better than the
isolated part of it. You can look at the ingredient of the product and it will
show whether it is a protein isolate or otherwise.
Do not seek out soy supplements such as soy protein powders or isoflavones. At this point, these are not really supportive
or necessary. Add some tofu to your diet and you will be just fine. Many of
those anti-soy studies were based upon isolated components as opposed to the
a healthy diet and lifestyle. You
need to follow a healthy lifestyle that includes the eight health laws.
Infants. Mother’s milk is still the best. As much as
possible the infant should get the mother’s milk. Cow’s milk is not a better
option. Soy infant formula has been used for over 50 years, and there is no
evidence of it causing developmental problems or reproductive problems. Cow’s
milk is highly allergenic, even though some people can be allergic to soy,
which does not mean we write it off for everybody. Also, cow’s milk can be a
factor in juvenile onset diabetes. Cow’s milk is not the better of the options;
it is better to choose soy.
Selecting soy. Select non-GMO (genetically modified
organism) tofu and soy products. There has been some preliminary exploration
that the GMO can alter the protein component in the blood. It is the principle
that the non-GMO is better.
All of the allegations or accusations are
very shaky. A couple of the anti-soy people consider cholesterol to be their
very best friend. That is also what the meat and dairy association said about
30 years ago. At that time they were advocating the necessity of dietary
cholesterol. They did this to promote their product. They actually want you to
eat saturated fat and not the plant oils. This,
combined with the unreliable accusations made, sugguests
that there is a particular agenda being promoted.
It is believed that the original humans were
hunters, who ate meat, and that is the diet we need to go back to. We do not
believe that. We believe that the original human beings were vegetarians. That
is what we were created to be, and that is the diet to which we should return.
Be very careful about advocating anything
with limited research on a few isolated studies or something that is not backed
up by epidemiology studies—population studies—seeing what they are eating and
not eating and seeing the results of the health status of that population. Stay
balanced, temperate and in the middle of the road and do not get sidetracked on
these various tangents.
Diane Herbert is a
naturopath and lifestyle consultant. She received training from the NAD
Lifestyle Consultant program, Thomas Edison State College, Clayton College of
Natural Healing, and Bastyr University. Diane teaches
health classes at the Gilead Institute located in Norcross, Georgia, gives
health presentations, and contributes to the Institute’s literature and health
flyer series. If you would like more information on water or other health
topics, you may contact her at: The Gilead Institute of America, 6000 Live
Oak Parkway, Suite 114, Norcross, Georgia 30093; telephone: 770-270-1087;