The (Partial) Vindication Of Soy Protein

The problem of the anti- nutrients found in soy protein has been taken care of as the manufacturers of high quality soy protein isolates remove them or dramatically reduce their activity during processing, so this is not a big point of concern anymore. Also, the addition of methionine to soy isolates greatly improves its BV and nutritional value, though it still does not reach the BV of whole egg or a good whey protein for that matter. Rats fed soy protein enriched with methionine grew at a similar rate as those fed casein.

As for the estrogenic compounds found in soy, that's a bit more complicated. For years, soy protein has been found to reduce cholesterol in a wide range of animals species and man. One recent study found that when they separated the estrogenic compounds from soy, it failed to have the usual cholesterol lowering effects. This does not come as a big surprise as the cholesterol lowering protective effects of estrogen are well known.

However, soy protein appears to have several mechanisms by which it lowers cholesterol (i.e. isoflavones, endocrine effects, fiber, saponins, etc.) and its mechanism on cholesterol probably depends on the animal species being studied. In addition to soy proteins ability to reduce cholesterol, epidemiological research also suggests soy can reduce certain forms of cancer and longevity companies such as the Life Extension Foundation are now recommending soy protein isolate for the treatment of certain cancers.

Soy Protein and Bodybuilders

Ok, now here is where things start to get interesting as it applies the bodybuilders. Though soy proteins contain these estrogenic compounds, it appears that they are "tissue specific." One study that used Rhesus monkeys found that soy proteins had no effects on the reproductive hormones of these animals. Testosterone, DHEAS, sex hormone binding globulin (SHBG), testicular weight, prostatic weight, and other measurements were taken.

They found no difference between male animals who ate soy protein that contained the plant estrogens and those who ate soy with the estrogens removed, leading researchers to conclude: "thus, the isoflavones (genistein and diadzein) in soy protein improve cardiovascular risk factors without apparent deleterious effects on the reproductive system..., " and "Genistein's effects appear to be tissue specific, with estrogen agonist effects on plasma lipid concentrations, plasma lipoprotein distributions and preservation of bone mass that are similar in magnitude to mammalian estrogens, but without estrogenic effects..." They finally conclude "Our data support an interpretation that soy beans estrogens have tissue specificity in part because of their mixed estrogen agonist and antagonist properties."

From this and other data, it seems the phyto estrogens in soy can lower cholesterol and improve heart disease risk without systemic estrogenic effects (i.e. gyno, bodyfat increases, etc.) that would normally be seen if say a bodybuilder took estrogen pills or from the conversion of certain steroids to estrogen. This study is a little more relevant to us humans being it was done with male monkeys which are far more similar animals to people than rats.

However, I think that an upper level of soy protein that contains phyto estrogens could cause systemic estrogenic effects if enough were taken, but that's only speculation on my part. Also, the use of soy isolates by men might be better cycled rather than taken all the time being we are not 100% sure at this time about the long term estrogenic potential of soy proteins in athletes. The ability of soy protein to lower cholesterol without other estrogenic effects could be useful to bodybuilders using anabolic steroids who tend to see a rise in cholesterol and/or LDL.

Now I have saved the best part for last regarding the upside of soy proteins. Soy protein has been found to raise thyroid output in a wide range of animals from rats to rabbits and pigs. Studies done with human subjects have been harder to quantify (what else is new?), but several studies suggest an effect on thyroid hormones in people eating soy protein isolate.

So what does the above information mean to the bodybuilder? There are two points I think are the most relevant to strength athletes.

(1) Though thyroid hormones are considered catabolic hormones, they are actually more catabolic to fat and carbohydrates, but stimulate protein synthesis if adequate calories are eaten and the amounts of thyroid hormones are not to high. This could be useful for increasing protein synthesis and reducing bodyfat. More research needs to be done in this area of course.

(2) When a person diets the success of that diet is quickly brought to a screeching halt when the body figures out what you are up to and reduces the output of thyroid hormones. This is a reaction by the body brought on by a reduced caloric intake which reduces metabolic rate and a new caloric set point is established and the dieter is now screwed! The use of soy protein isolate to boost thyroid output could be exactly what the doctor ordered to keep thyroid levels raised during reduced calorie intake when dieting if the above evidence with soy proteins and thyroid function holds true in humans on reduced calories diets. Lets hope it does!

Solving The Soy Dilemma

Taking all of the above information on soy protein that we have looked at in this article I think we come up with something of a dilemma for the bodybuilder. For the average person, there is no real dilemma here as they don't care much about protein quality. Unfortunately, if a bodybuilder starts to replace too much of the other high quality proteins in their diet in favor of soy to reap some of the potential benefits of soy, than he (or she) runs the risk of losing muscle due to this lower quality protein.

This would be particularly noticeable during a reduction in calories (i.e.dieting). The lower the calorie intake the higher the quality of protein needs to be to maintain lean body mass. Make no mistake about it, soy protein does not have the nitrogen retaining, anti catabolic, muscle building abilities of proteins such as whey, whole egg, red meat, etc. However, soy does appear to have some other real benefits to the bodybuilder. So what do we do? So far, it appears that a person does not need to eat a great deal of soy protein isolate to get the benefits. Estimates of ten - thirty grams a day of a high quality soy protein isolate should do the trick for most people.

This is how I solve the dilemma and I have found this strategy works well for people. By mixing a high quality whey protein powder with a high quality soy isolate in a 2:1 ratio and eating that two - three times a day, the bodybuilder can have the best of all possible worlds (as it relates to the high BV, immune enhancing, nitrogen retaining abilities of the whey and the cholesterol lowering/thyroid stimulating abilities of the soy). To date, I have no reason to believe that mixing these two proteins will negate or interfere with the benefits or properties of either protein, but there is scant research in this area with healthy athletes. Anecdotally, the people I have told to do this mixture have given me mostly positive feedback so far.

Plain and simple, mix in a blender two scoops of whey protein to one scoop of high quality soy protein isolate and take the mixture two-three times per day. In fact, I think with a few other key ingredients, this could make a real nice pre mixed meal replacement product for use when dieting. For now however, you can make it yourself and you might be surprised at the results...

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