Soy vs Whey

Soy Vs. Whey, Carlon M. Colker, M.D.
Proteins Duke it Out for Prominence,
but Only One is a True Champion
Carlon M. Colker, M.D.
Although debated for years, it is now not merely a widely held belief, but an accepted fact, that athletes and people who exercise need more protein than sedentary non-exercising individuals.1-9 But as protein has gained in popularity and finally assumed its rightful place as king of the macronutrients, a new war has begun. The battlefield has been drawn, pitting all available sources of protein against each other in an all-out brawl to see which rules. In the words of Apollo Creed- when he was set to face the Italian Stallion- “Sounds like a damn monster movie!” Of course, if you’ve been paying attention to the media, you know that two top contenders have emerged.
Hold the fort down fight fans, and let’s get ready to rumble! In the blue corner, a lower quality protein weighing in without all the essential amino acids, a debatable cardio-protective effect, and a known and worrisome phytoestrogen content soy protein. In the red corner, the highest quality and biologics value protein, weighing in with all the essential amino acids, immune enhancing powers, and offering greater cancer protection than soy – whey protein!
Sounds like a mismatch to me. Of all the protein sources out there, you might wonder why these two have emerged as top dogs. The answer is that whey protein is in contention as a result of a wellspring of supporting research and scientific fact. Soy protein, on the other hand, has emerged for honors simply because of clever exaggerations of flimsy studies, as well as misleading propaganda driven by a powerful and profit oriented soy lobby.
Sorry soy enthusiasts, if I’ve touched a sore spot. But let’s examine this issue further and include the important basic differences, as well as some of the latest research on both these proteins.
The Big Lie
First of all, I’m tired of hearing all this garbage about soy being a complete protein (meaning it contains all the essential amino acids our bodies can’t synthesize from other sources and must instead directly consume). Don’t let anyone shove this lie down your throat. Soy protein is not a complete protein because it lacks the amino acid methionine. This is a non-debatable scientific fact.
Whey protein, on the other hand, lacks no essential amino acids. As a result, it has a much higher biological value in terms of similarity to our own human protein. Whey protein beats soy protein hands down in this category simply because whey protein needs no fortification or additive to make it complete. It is complete in its natural form.
Perhaps the greatest coup for soy fans of late was approval by the FDA for soy-containing products to be listed as able to reduce the risk of heart disease This government seal of approval was not only premature, but also potentially dangerous. There was, and still is, no solid scientific research to back such cavalier support by our government. I wonder how a government steeped in the practice of forcing products to be thoroughly researched and tested before claims can be made, would do something so reckless.
The fact is, soy has no more impressive research to support such broad-based government support than that which supports whey protein in the area of heart health. The research supporting soy as cardio-protective is almost completely epidemiological and observational across broad spectrums of the population. In fact, as far as whey protein is concerned, nearly a decade ago the Chinese demonstrated the cholesterol and plasma lipid lowering ability of whey protein.10 But this, along with piles of subsequent research, hasn’t motivated the government to give whey protein the same whorish kiss it gave soy.
Much Ado About Estrogen
I think what’s really going on starts with the soy lobbyists. Soy is big business. Nearly a million metric tons have come into this country this past year alone; nearly $500 million worth of soy products moved off supermarket shelves just last year.11 When big bucks are on the line, lobbyists find the motivation to aggressively seduce government.
A lot of support for soy being heart healthy stems from soy enthusiasts focusing on the estrogenic effect of soy. Soy contains genistein and other phytoestrogens that are hormonally akin to estrogen. Unfortunately, it now appears these folks have jumped the gun. A landmark study in the Journal of the American Medical Association looked at estrogen therapy and the prevention of heart disease.
The study showed that over four years, estrogen treatment did not reduce the rate of heart disease in postmenopausal women. In fact, it increased the rate of blood clots and gallbladder disease! The conclusion of this comprehensive study of nearly 3,000 subjects sent a clear message to physicians that, while it might help bone density and lessen the chance of hip fractures, estrogen therapy does not protect the heart. Thus, it should not be given for preventing heart disease. “Based on the finding of no overall cardiovascular benefit and a pattern of early increase in risk of CHD (coronary heart disease) events, we do not recommend starting this treatment for the purpose of secondary prevention of CHD.”12
Thus, those taking soy as an estrogen analog for protection against heart disease have been woefully misled by the propaganda. In fact, as the research clearly shows, the road of estrogenic substances is filled with perils., Why the soy supporters and the FDA have ignored this, is beyond, my comprehension. I should highlight here that, unlike soy protein, whey protein has no phytoestrogen content. And, while the exact mechanism remains unclear, the cardioprotective effect, if any, probably has more to do with a powerful antioxidant effect that benefits the entire body, not just the heart.
There are other problems with exposure to estrogens and estrogen-like substances, namely cancer. Somehow soy got labeled a cancer preventive! The absurdity of this flawed logic makes me laugh; the potential health ramifications of the misinformation make me cry.

Receptor Site Skirmish
The theory behind soy as a cancer preventive stems from the fact that the phytoestrogens in soy protein, although estrogen-like in function, are weaker receptor stimulators than the estrogens in our bodies. When this weaker estrogen is put in the body, it competes with the body’s own estrogens for receptor sites. A temporary “blocking” effect is exerted because these estrogen-like compounds don’t stimulate the receptor to the same degree as actual estrogens. This is the mechanism of action of tamoxifin, a chemotherapy agent many soy supporters say soy protein is akin to.
The problem with this theory: While an estrogen-like substance might have a weaker stimulatory property on one area of receptors in the body, it may be stimulatory to the same degree as true estrogen at other receptor sites. It’s for this reason drugs with more estrogen site specificity are currently being developed. New drugs like raloxifene appear to have estrogen site selectivity so that, for the postmenopausal female, the risk of osteoporosis is reduced without stimulating uterine or breast cancer.13
So, while phytoestrogens in soy might be weaker estrogens at some sites in the body and thus help prevent cancer spurred by the body’s own unopposed estrogens, it has no receptor site specificity, and thus may actually stimulate cancer, in other areas of the body.14
In fact, in recent discussions with prominent cancer specialists and colleagues at the world renowned Memorial Sloan Kettering Cancer Center in New York, the subject of soy protein came up. All three specialists I spoke with are telling successfully treated breast cancer survivors to avoid soy. Of even greater interest was that they maintained this recommendation even for those individuals whose cancer was deemed “non-estrogen dependent” (i.e., estrogen receptor negative). They said they did this “just to be on the safe side.”
Russian Roulette?
But, thankfully, the public is getting hip. In a recent New York Times article, prominent physician researchers called our attention to the potential perils of soy. Dr. Margo Woods at tufts University School of Medicine, Dr. Gregory Burke at Wake Forest University School of Medicine, Dr. William Helferich at the University of Illinois, and even the FDA’s own research biologist at the National Center for toxicological Research, have all voiced very serious concerns.”
My recommendation would be to examine your family history carefully. If you have a history of cancer (especially breast), consider soy a danger.
But if it’s cancer prevention you’re interested in, without playing Russian roulette with the phytoestrogens found in soy, take a good look at whey protein. More than a decade ago, whey protein demonstrated an ability to prevent cancer and tumor growth.15
The current thought is, in much the way whey protein may be cardio-protective, the key mechanism of action has to do with whey’s unique ability to bolster the immune system by increasing intracellular antioxidant power.
We have all heard of vitamins E and C and their antioxidant ability in the bloodstream. But, a far more powerful and target-specific antioxidant exists within each living cell called gamma-L-glutamyl-L-cysteinyl-glycine, more easily referred to as GSH (Glutathione). This powerful antioxidant exerts its action within the cell. In fact, it cannot only be synthesized inside the cell from smaller molecules since there is no efficient transport mechanism to get GSH from the blood stream into the cells.
The key building block for GSH is an amino acid called cysteine. When two molecules of cysteine are coupled and then linked by a disulfide bond, the result is a molecule called cystine. This cystine molecule is not only stable, but travels easily through the body and into each living cell. Once in the cell, it’s broken down into cysteine molecules; and used to form GSH.
Because of whey protein’s unmatched biological value, bioavailability, impressive solubility, level of absorption, and high percentage content of cystine residues and branch chain amino acids (23 percent), it’s the superior form of protein supplementation for athletes.16 Though moderate exercise has been shown to improve immunity, intense exercise has been shown to reduce GSH levels, which are associated with immunosuppression.17 This negative effect on immunity is directly related to the intensity and duration of the physical activity and immune status of the athlete. Over the past decade it has been shown that whey protein possesses immune enhancing properties that can help the athlete recover and avoid over training syndrome.18
Unlike soy protein, which is profoundly deficient in these and other sulfur-containing amino acids whey protein (in particular, the concentrate form) contains an abundance of highly biologically active cystine residues, thus making it a powerful immuno-modulator against cancer, toxins, infections, or any other bodily insult.19
Staggering News
In support of the notion of whey being protective, against cancer, a recent study published by the American Association for Cancer Research compared whey Protein to soy protein and casein (a low order milk protein). The article concluded that “Whey appears to be at least twice as effective as soy in reducing both tumor incidence and multiplicity.”20 This staggering news has profound ramifications with respect to choosing between soy protein and whey protein.
Furthermore, the same “cysteine donor” effect unique to whey and not found in soy, that seems to be at work in preventing cancer, has recently been shown to enhance muscular performance and decrease muscular fatigue. Another recent study concluded that prolonged supplementation with a product designed to augment antioxidant defenses resulted in improved volitional performance.”21 Remember, this characteristic is unique to whey and something soy simply cannot achieve because it is not a cysteine donor.
Going back to the issue of soy containing phytoestrogens, the problem may be worse for men than for women.
The research indicates that these phytoestrogens are not as weak and harmless as soy enthusiasts would lead you to believe. In fact, when genistein (the main phytoestrogen in soy) Was given to mice in doses similar to those contained in an average soy-based diet, in only nine days testosterone concentration was dramatically reduced. The reduction seemed to stem from a decrease in production of luteinizing hormone, secreted by the anterior pituitary gland.22 In fact, several other animal studies clearly indicate the rather frightening feminizing effect of unopposed estrogen stimulation in the form of dietary phytoestrogens.23,24
My own fight card says soy loses yet another round. Stick with whey, unless of course you want to get in touch with your feminine side.
Moreover, another recent, study by Dr. Stephen Liu of UCLA Medical Center, demonstrated the influence of estrogen on weakening ligaments and thus increasing the probability of injury. This would explain why women are up to six times as likely as men to suffer an anterior cruciate ligament tear.25 Although this research is somewhat controversial and preliminary, it warrants careful examination. As with the concerns over soy protein negatively influencing thyroid function in children, don’t discard these possible early indicators of what could become a serious health issue as the soy juggernaut rolls on unopposed.
As we near the end of the final round, know that the research continues to mount supporting whey as the protein of choice and, unless used carefully only in select cases as a medicinal food, soy is far inferior and dangerously problematic. In this head-to-head battle, soy protein is simply outclassed by whey. But since the Don Kings of the soy industry are showing no signs of letting up on the pro-soy hype, something tells me this mismatch is destined for a rematch.


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