Soy is a legume commonly used in meatless food products, and is an ingredient in some protein supplements commonly used by bodybuilders and other athletes. Soy comes from soybeans and is used as a meat substitute. Since soy is a complete protein some athletes use it to help meet their increased dietary protein needs. Soy provides non-animal protein and supports a high-protein, low-carb diet that is well tolerated by lactose-intolerant individuals.
Types
Two types of proteins exist -- complete and incomplete. Complete proteins contain all of the essential amino acids the human body needs to make and utilize proteins. Amino acids, the building blocks of protein, are considered essential if the body cannot make them. Complete proteins are mainly found in animal-based food products such as meat, chicken, fish, seafood, eggs, dairy products and certain protein powders derived from casein or whey; however, soy is the only plant-based source of complete protein.
Benefits
Choosing soy over other types of proteins such as casein or whey, may convey certain health benefits. According to the National Center for Complementary and Alternative Medicine, consuming soy on a daily basis may lower low-density lipoproteins -- the "bad" cholesterol that contributes to heart disease. The National Center for Complementary and Alternative Medicine also notes that soy consumption from foods or supplements is safe for most people when taken for short periods of time.
Concerns
Soy products and supplements contain isoflavones, which are compounds that resemble estrogen, a female hormone. Since estrogen inhibits muscle growth, some bodybuilders avoid soy protein even though soy isoflavone compounds are only "estrogen-like." The safety of long-term soy isoflavones use has not yet been established.
Expert Insight
The American Dietetic Association reports that research shows high-quality proteins such as soy, whey or casein are effective for skeletal muscle repair, maintenance and synthesis after strength-training. The American Dietetic Association also notes that protein consumed by athletes in close proximity to a strength-training workout can enhance net skeletal muscle gains.
References
- US Department of Health and Human Services Office if Minority Health: Key to Nutrition: A Diversified Portfolio
- National Center for Complementary and Alternative Medicine: Soy
- American Dietetic Association: Position of the American Dietetic Association, Dietitians of Canada, and the American College of Sports Medicine: Nutrition and Athletic Performance
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