The Scary Truth About Soy Protein and Bodybuilding

Copyright 2006 Marc David
Inevitably there’s a myth that soy protein is horrible for bodybuilding and that if you are any where near serious about working out or building muscle you will stay away from it. In fact, some sites show ‘studies’ that soy protein and soy products can be detrimental to your health. And while it’s true that early claims of soy wonders might not be entirely true, there’s also myth that soy protein is bad.
First off, there’s a concept called the Biological Value Scale that was developed to measure the quality of specific proteins. It basically rates how efficiently your body will use a given protein source. The higher the BV (biological value), the more amino acids and nitrogen your body is retaining from the foods you eat. In sum, it becomes a way to measure the potential for quality muscle growth and strength.
There was a time when egg whites were at the top of the BV with a score of around 100. Since then, whey proteins have toped out the scales around 106-159 BV. This means that whey protein is better used for quality muscle growth.
But first a warning!
This doesn't mean that all you would utilize is whey protein for all your needs. Many times bodybuilders will use a variety of proteins depending on the BV and the times of day and if they just finished a workout.
Let me explain… Your protein needs in the morning are different then the middle of the day and are different again AFTER a workout and again different before bed.
All this means is that no one protein is the best for any given time. But before I get lost... let me show you the biological value scale in a simple form.
Type of Protein :: Biological Value Rating
Whey: 106-159 Egg: 100 Cow’s Milk: 91 Fish: 83 Casein: 80 Beef: 80 Chicken: 79 Soy: 74 Wheat Gluten: 54 Kidney Beans: 49
For all these reasons, you can and should see that soy protein is listed lower. That just means it’s not the most anabolic of proteins for optimal muscle growth.
But don’t get me wrong...
This doesn't mean you shouldn't eat soy protein if you enjoy it. It simply means that barring any religious beliefs or personal preferences, soy would not be the ideal protein source for enhanced muscle gains. This doesn't mean you cannot have it or that it’s bad for you.
In fact, let’s continue on with a little example.
John Q. Public 13% body fat 184 lbs 160 lbs of LBM (lean body mass)
For simplification we'll just say that for every LB of LBM (pound of lean body mass) John wants to get 1 g of protein.
John should be consuming 160 g of protein a day.
Here’s where the myth and some problems come into play! Read carefully.
If you get a vast amount of your protein from less BV sources then optimal (beans, soy) you will not prime your muscles for optimal anabolic growth. John shouldn't be getting 150+ grams of soy protein a day IF he wants to create the most muscle mass and he has no personal reasons not to use better quality sources.
John also won’t be in jeopardy of losing muscle or wasting his efforts if he ingests small quantities of soy proteins because he likes them. Having soy in his cereal is not going to make a difference.
The myth that soy will cause men to produce estrogen is when VAST quantities are ingested. Far beyond what any rational person would want to do on a prolonged basis.
A bodybuilder that has soy will not feel any differences, be any less anabolic then another person who does not consume soy at all.
Fact: A long-term metabolic balance study in young men to assess the nutritional quality of an isolated soy protein and beef proteins (VR Young, A Wayler, C Garza, FH Steinke, E Murray, WM Rand, and NS Scrimshaw) was published in 1984 by the American Journal of Clinical Nutrition. Am. J. Clinical Nutrition, Jan 1984; 39: 8 - 15.
After 84 days of two groups, one totally isolated soy protein and the other on beef proteins, found a conclusion that:
"Body cell mass measurements did not reveal any deterioration in protein nutritional status. These observations confirm the prediction, derived from previous short-term nitrogen balance studies, that the nutritional quality of isolated soy protein is high and that this plant protein can serve as the sole source of essential amino acids and nitrogen for protein maintenance in adults."
So let me summarize and review...
Soy is not the most biological available source for optimal anabolic muscle growth. If you were to finish a workout, you would want to ingest some high quality whey protein vs. soy proteins. However, simply having soy doesn't mean it’s bad for bodybuilding unless you are getting a majority of your protein from soy products. Then it’s not optimal. You’d also need to ingest quite a bit on a daily basis for any negative effects of soy to manifest (specifically aimed at males in this sentence).