Soy Protein Review
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Are Soy Products And Supplements Good For Athletes
By Ivan Nikolov
copyright © 2008 Ivan Nikolov
Is soy suitable for use in athletes and ordinary people?
This was the question that has been bothering me for quite some time. I will
give you a little bit of my background. It is something that I don’t include in
I started training with weights when I was 15. Back in these days the democracy
was a new thing in my country, and the prices were going up just because as a
new democracy we had to level our currency with the courtiers from the West.
The salaries however weren’t going up as fast as the prices were. So, at that
time the most an athlete could afford to set aside for a protein supplement was
only enough for some cheep grade soy protein concentrates.
Needless to say I must have eaten a truckload of soy protein back then. In
those days I didn’t have the knowledge and I didn’t have the easy access to
educational resources I have nowadays. Moreover, there wasn’t too much of a
literature on this issue either (I now realize).
So, keeping in mind my early history in the sport of natural bodybuilding, my
hunger for better understanding of the possible advantages and disadvantages of
soy and soy proteins increased exponentially. I recently decided to do my usual
digging and find the information I needed to help me put the pieces together.
When I started my search I didn’t even realize how hard of a task this is going
to turn out to be. Being determined to once and forever find the truth I made the
decision to continue no matter how much time this is going to cost me.
To keep this short here is what I did. I found quite a few
articles and other published material but there were a few that stood out. Of
course they all came from the two main camps: the pro-soy and the anti-soy. I
thought I’d put these against each other in an imaginable, virtual dispute.
The main articles were: “Tragedy and Hype” by
Sally Fallon and Mary G. Enig, “What
About Soy?” by John Robbins, and “Think Soy is Healthy?
Here’s Why it’s Not as Good as You Think” by Dr. Joseph Mercola.
Sit back and watch the dispute.
Argument: Cholesterol Lowering Abilities of Soy
Accusation: From the anti-soy camp: “…The
published report suggested that individuals with cholesterol levels over 250
mg/dl would experience a "significant" reduction of 7 to 20 percent
in levels of serum cholesterol if they substituted soy protein for animal
protein. Cholesterol reduction was insignificant for individuals whose
cholesterol was lower than 250 mg/dl.”(i) Note: Total cholesterol levels of
over 200 mg/dl are considered high.
Defense: The argument of the pro-soy
camp: “…The kernel of truth in Fallon and Enig's statement is that soy
consumption tends to bring down total cholesterol levels most in people whose
cholesterol levels are high. But even people with normal levels benefit from
eating more soy, according to dozens of studies, because it improves the ratio
between HDL (good) and LDL (bad) cholesterol. This ratio is now recognized by
the American Heart Association to be an even more important factor than total
cholesterol levels in heart disease risk…”(ii)
Arbitration: In his article Dr. Mercola comments on the
Robbins’s (pro-soy) argument about the cholesterol lowering properties of soy:
“Robbins ascribes soy’s potential to lower cholesterol as beneficial. However,
while this may be helpful in some, it can certainly cause disease in others.
Low cholesterol does not necessarily imply good health. This is because we all
need cholesterol and levels below optimal can cause serious problems. Much of
the hype about cholesterol has been generated by self-serving research used to
support the massive profit structure of pharmaceutical companies supplying
Argument: Phytic acid (phytates)
Accusation: “Soy and soy products are
high in phyitic acid (phytates) – an anti-nutritive compound, which in large
amounts blocks the uptake of some essential elements such as calcium,
magnesium, copper, iron and zinc. The soybean has one of the highest phytate
levels of any grain or legume that has been studied, says the anti– camp, and
the phytates in soy are highly resistant to normal phytate-reducing techniques,
such as long, slow cooking.”(i) Phytic acid decreases more readily the
absorption of zinc that that of the rest of the minerals.
Fallon and Enig admit however that phytate levels can be
significantly reduced through a long period of fermentation. Through a process
called precipitation (as in tofu) the phytates are decreased as well but not as
much as through a process like the fermentation.
Defense: J. Robins in his article: “…The
phytic acid levels found in a plant-based diet including a serving or two of
soy a day is not high enough to cause mineral absorption problems for most
people eating varied diets (ii). Furthermore, Robbins says, when soy products
are fermented - as they are in tempeh, miso, and many other soy foods - phytate
levels are reduced to about a third their initial level. Other methods of soy
preparation such as soaking, roasting and sprouting also significantly reduce
Arbitration: Here is what Dr. Mercola
says on the comments of J. Robbins on the phytic acid content: “…This is one
area where I disagree with Enig and Fallon partially in that the phytic acid in
soy (and other plant products like beans, nuts and seeds) may be beneficial or
detrimental, it just depends.
For men phytic acid is probably very helpful as nearly all adult males have
excess iron as we never had menstrual periods. I personally take a phytic acid
supplement to lower my iron levels. However, in menstruating women and children
the phytic acid in soy can be a serious negative.
In his arguments Robbins correctly points out that fermented soy products have
lower phytic acid than commercial soy products. However, he does so as to
contradict Fallon and Enig, but this is exactly what they also state. They have
no problems with fermented soy products and encourage their consumption.”(iii)
It should be kept in mind that phytates interfere mainly with the zinc
absorption. Zinc is a major mineral in the athletes diet as it is involved in
the steroid hormone production. It is also needed for the proper functioning of
the brain and nervous system, protein synthesis, collagen formation, and blood
Argument: Enzyme inhibitors (trypsin inhibitors)
Accusation: Among the anti-nutrient
substances in soy and soy products there are the so-called enzyme inhibitors.
What they do is they block the action of trypsin and other enzymes, needed for
protein digestion. The anti-soy camp says: “these substances retain their
configuration even when heated for long periods of time and can produce serious
gastric distress, reduced protein digestion and chronic deficiencies in amino
Defense: Robbins acknowledges that
“…there is a kernel of truth behind these charges,” but according to him these
charges are “greatly overstated”. He continues “It is true that the protein in
cooked soybeans is slightly less digestible than that found in most animal foods.
However, when soybeans are made into soymilk, tofu, tempeh, and the other
common forms of soy foods, their protein digestibility is enhanced and becomes
similar to animal foods. Any negative impact on protein digestibility due to
the presence of the enzyme inhibitors found in soybeans is rendered nearly
irrelevant in such foods.”(ii)
Argument: Hemagglutinin and Goitrogens
Accusation: The anti-soy camp pulls the
argument about the hemagglutinin content in soybeans. Hemagglutinin is a
clot-promoting substance, which causes red blood cells to clump together. They
admit however that hemagglutinin and the trypsin inhibitors (which they call
‘growth depressants’) become deactivated during the process of fermentation
(miso, tempeh, natto). However, they warn: “In precipitated products (tofu),
enzyme inhibitors concentrate in the soaking liquid rather than in the curd.
Thus in tofu and bean curd, growth depressants are reduced in quantity, but not
“Soy also contains goitrogens, they say -- substances that
depress thyroid function, a fact that has been known for at least 50 years.”
Goitrogens lead to decreased Thyroid Hormone (TH) production, which in turn
leads to increase in the Thyrotropin-Stimulating Hormone (TSH or Thyrotropin).
High levels of TSH cause hyperplasia (increase in size) of the thyroid gland in
an attempt to normalize thyroid hormone levels. This condition is known as
Defense: In the pro-soy camp: “It is true that soybeans
contain these substances. But there is little evidence that as a result
soybeans represent a health danger to humans. Moderate amounts of soy foods
have been eaten happily by entire civilizations for thousands of years.”(ii)
Argument: Genetically Modified Soy (GMO)
Accusation: Surprisingly it comes from
the pro-soy side. Here is what J. Robbins says in his article “What About Soy?”
“There are legitimate questions about soy. One of the most
recent, and most disturbing, stems from the fact that two-thirds of the U.S.
soybean crop today is genetically engineered. These are beans that have been
genetically altered to enable the growing plants to withstand being sprayed
with weed killers, particularly Monsanto's Roundup. For the technology to be
commercially viable, the FDA had to triple the residues of Roundup's active
ingredients that can remain on the crop…
…According to Monsanto's own tests, Roundup Ready soybeans
contain 29 percent less of the brain nutrient choline, and 27 percent more
trypsin inhibitor, the potential allergen that interferes with protein
digestion, than normal soybeans. Soy products are often prescribed and consumed
for their phytoestrogen content, but according to the company's tests, the
genetically altered soybeans have lower levels of phenylalanine, an essential
amino acid that affects levels of phytoestrogens. And levels of lectins, which
are most likely the culprit in soy allergies, are nearly double in the
I find it fascinating that compared to regular soybeans, the genetically
engineered beans have more of the very things that are problematic, and less of
the very things that are beneficial. To my eyes, this is certainly another
reason to eat organic foods whenever possible. The best way to insure that any
soy foods you eat are not genetically engineered is if they are organically
Defense: No defense here!
Accusation: “…(Soy Protein Isolate) production takes place in
industrial factories where a slurry of soy beans is first mixed with an
alkaline solution to remove fiber, then precipitated and separated using an
acid wash and finally neutralized in an alkaline solution. Acid washing in
aluminum tanks leaches high levels of aluminum into the final product” (higher
amounts of aluminum have been found in the brains of people with Alzheimer's
“The resultant curds are spray dried at high temperatures to produce a high
protein powder... Much of the trypsin inhibitor content can be removed through
high-temperature processing, but not all. …High-temperature processing has the
unfortunate side effect of so denaturing the other proteins in soy that they
are rendered largely ineffective.
Nitrites, which are potent carcinogens, are formed during
spray drying, and a toxin called lysinoalanine is formed during alkaline
processing. Numerous artificial flavorings, particularly MSG (Monosodium
Glutamate), are added to soy protein isolate and textured vegetable protein
products to mask their strong "beany" taste, and impart the flavor of
and Cancer Link
Isoflavones are the estrogen-like compounds, found in soy
and soy products. They are often recommended for use from menopausal women for
providing relief from hot flashes. 45 gr. of isoflavones (contained in just
over 20 gr. of soy protein isolate) have shown to exert significant biological
effect in women.
Accusation: “One hundred grams of soy
protein, the maximum suggested cholesterol-lowering dose (and the amount
recommended by Protein Technologies International), can contain almost 600 mg
of is flavones (genistein and diadzein), an amount that is undeniably toxic. In
1992, the Swiss health service estimated that 100 grams of soy protein provided
the estrogenic equivalent of the pill (birth control pill)…
…The logic that links low rates of reproductive cancers to
soy consumption requires attribution of high rates of thyroid and digestive
cancers to the same foods, particularly as soy causes these types of cancers in
The following paragraph comes from the pro-soy article of
J. Robbins: “…Although soy consumption on the whole reduces
cancer incidence, there are questions about its effect on women who have
estrogen-positive (ER+) breast tumors. These tumors are stimulated by estrogen.
Might they therefore be stimulated by the weak estrogenic activity of the
isoflavones found in soy? There is some evidence this may be the case, though
there is also evidence that soy consumption favorably alters the metabolism of
estrogen so that it is less likely to stimulate tumor growth. At this point,
given the uncertainty, women with ER+ breast cancer should probably avoid
eating more than three or four servings of soy a week.”(ii)
And again from the same article: “Although there is no
firm evidence to demonstrate that ingestion of isoflavones has adverse effects
on human beings, there is also no clear evidence that large doses are safe.
When manufacturers of soy protein isolates and supplements recommend that
people consume 100 grams of soy protein a day (the equivalent of 7 or 8 soy
burgers), they are ignoring the unknown effects of overdosing on isoflavones. I
believe it's probably safer, until more is learned, to avoid concentrated soy
Defense: Nobody on this side again.
So, is Soy Protein Isolate (SPI) suitable for consumption
Let’s summarize what we learned about SPI so far:
SPI, being non-fermented soy product, contains phytic acid
(phytates). This can be okay for some men with significantly higher levels of
iron. On the other hand we should keep in mind the fact that phytates reduce
the absorption of other essential minerals such as calcium, magnesium, zinc and
copper. Women, being chronically iron deficient are better off staying away
from SPI supplements.
The defense failed to convince us that the presence of enzyme inhibitors in soy
products and SPI is “irrelevant”. The enzyme inhibitors in SPI block the action
of the protein digestive enzymes thus decreasing the rate and the amount of
protein absorption. But isn’t this the main reason why bodybuilders would take
SPI contains hemagglutinin, a substance that causes erythrocytes (red blood
cells) to clump together.
Goitrogens, also in SPI, cause thyroid gland enlargement.
Two thirds of the soy production is GMO (genetically modified), which means
that the chances for a particular SPI supplement to be made of GMO soy are 66%.
This is a quite disturbing number given the fact that GMO soy products contain
less of some of the amino acids that make for the not even that good amino acid
profile, and more of the anti-nutrients, already discussed above.
Nitrites, aluminum, lysinoalanine, and MSG (Monosodium Glutamate) can be found
in the already processed SPI.
The amount of naturally occurring isoflavones in soy is about 50 mg per 25 gr
of SPI. An athlete on a high protein diet, who provides some of the protein in
his/her diet from SPI will easily consume at least two times that amount a day.
This, according to the Swiss health service equals to a half (!) of an estrogen
Going back to where I started I think I already had enough
of all that for the rest of my life. However, I ought to mention that although
the large amounts of SPI and SPC (Soy Protein Concentrate) I’ve consumed during
my early years in this sport I personally haven’t experienced any noticeable
side effects nor have I witnessed anybody to have experienced such.
I think I will stay away from SPI and all other commercial
soy products including fresh green soybeans, whole soybeans, sprouts, flour,
soy milk and tofu at least till the moment when they will be able to produce a
SPI supplement, which won’t exhibit all (or at least many) of the negative
effects, mentioned in the list above. The only soy products I will eat in
moderation are the fermented like miso, tempeh, natto, fermented tofu, and
fermented soy sauce, and only if they are organic.
Finally, as always I will leave it up to you to decide for
yourself whether you will continue to eat soy products and supplement with soy
proteins. I hope my efforts in gathering the necessary information will be
sufficient for you to make an informed decision on your own.
Sally Fallon, Mary G. Enig; Tragedy and Hype
John Robbins; What About Soy?
Joseph Mercola; Think Soy is Healthy? Here’s Why it’s
Not as Good as You Think
James R. Mulinda; Goiter
Mercola; Soy Bad, Soy Good: The Pluses of Fermented Soy
ABOUT THE AUTOR
Ivan Nikolov, an accomplished natural bodybuilder shares a
wealth of information on Natural
Bodybuilding and Sports
Nutrition on his website www.IvanNikolov.com.
Start using his comprehensive Free Nutrition
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