The (Partial) Vindication Of Soy Protein

Once an industry or an individual has set a position on something, they would rather ignore new evidence to the contrary then change their position. As for me, if I find new information on something that alters my position, that's fine by me. I just change it to reflect the new information, which is exactly what I had to do with my view on soy proteins. The article did finally get published in MuscleMag International. MMI might have its faults, but they are one of the most open minded and flexible magazines and didn't have any problems with publishing this article with them. Hope you all find it useful.

Soy Protein (1)

Not more than a month ago, I was standing in a field of soy beans in Peoria Illinois doing a commercial for a Japanese film crew. The guy to the right of the camera was holding up my little cue card as I said "Soy products have been shown to reduce cholesterol and possibly prevent cancer, yada, yada, yada..." I found it hard to keep a straight face and say nice things about soy protein as I have always considered soy protein basically a waste of time for bodybuilders. However, this commercial was for "normal" people so I did not feel like a "sell-out" for saying positive things about soy protein. On the plane ride home, with a glass of red wine firmly in hand, I decided to take a closer look into the properties of soy proteins and see if there were not some useful applications of this protein for bodybuilders after all.

The bodybuilding community has been pretty hard on soy protein generally relegating it to "crap" status among most bodybuilders and bodybuilding nutritionists. I will be the first to admit I have helped the negative reputation of soy among bodybuilders along by telling them how inferior it is to such proteins as whey or egg in various articles and my book. I still think soy protein is inferior to such proteins as whey and egg, but I do believe that it has some potentially useful applications if used correctly and tweaked just right. More on that later.

The Downside of Soy Protein

So why does soy have such a bad reputation among bodybuilders? On the surface, it would appear that soy protein is pretty lousy stuff for most athletes. Soy protein has a low BV score of 74. What does that mean? There are several ways of assessing protein quality. You have the protein efficiency ratio (PER), the net protein utilization (NPU) and the biological value (BV).

The PER is an outdated measure of protein quality and is not used much anymore by most supplement manufacturers or nutritionists "in the know" about protein quality. The NPU is a little better than the PER, but fails to take several important factors into account involved with proteins, such as absorption and digestibility, so it too is not used much either. That brings us to the BV. The BV is the most accurate indicator of biological activity of a protein and measures the actual amount of protein deposited per gram of protein absorbed.

In addition to its low BV score, soy has several other nutritional drawbacks that make bodybuilders avoid the stuff like it was fake D-bol. One reason soy is so low on the BV scale is it is lacking in the sulfur containing amino acid methionine. The sulfur containing amino acids (cysteine being the other one) are particularly important for protein synthesis/growth, proper immune system function, and the body's production of glutathione (GSH). GSH is one of the most important anti-oxidants found in the body and protects cells and serves to detoxify a variety of harmful compounds such as hydrogen peroxide, carcinogens, reactive oxygen species, and many others.

In particular, GSH is also partly responsible for keeping low density lipoproteins (LDL) from oxidizing and clogging our arteries. Several studies have shown soy protein to be inferior to whey for the production of GSH and improvements in immunity. Though soy has a reputation for reducing cholesterol in man and animals, in one study rats fed soy protein that was not fortified with methionine as 13% of total calories, had an increase in cholesterol and an increase susceptibility of LDL cholesterol to peroxidation .

So not only did the rats cholesterol go up, the LDL fraction oxidized easier potentially leading to clogged arteries. It is well established that an increased susceptibility of LDL to peroxidation is an essential step for the development of atherogenesis. These rats were found to have low levels of GSH and did not grow as well as another groups of rats fed casein.

If that were not bad enough to convince you to avoid soy, it gets worse. Soy protein contains something known as "anti -nutrients" that block the digestion and absorption of many nutrients. Two of the more important anti-nutrients found in soy are Lectins and protease inhibitors. Lectins are nasty constituents of various plants and can cause all sorts of problems from interfering with the absorption of important nutrients to intestinal damage. Proteases are enzymes that assist in the digestion of proteins.

Soy has several protease inhibitors that interfere with the enzyme trypsin and chymotrypsin, both of which are important for the digestion and absorption of proteins in the gastrointestinal tract. Finally, soy is rich in estrogenic compounds such as genistein and diadzein. There are over 300 plant derived phytoestrogens found that vary substantially in their physiologic effect and potency in animals and man. As any bodybuilder worth his weight belt already knows, a change in the testosterone/estrogen ratio in favor of estrogen can lead to increased bodyfat and other ill effects as it relates to the strength athletes goals.

BV of common proteins

Whey=104
Whole egg=100
Egg white=88
Casein=77
Soy=74
The Upside of Soy

Continue to Part 2 >>

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