Beef, tuna, eggs and chicken, along with dairy-based protein powders, are often seen as the go-to muscle-building foods and supplements, those on a veg or plant-based diet may need to look to other ways to get protein, such as with soy protein in food and supplement form.
The Soy and Estrogen Myth: One of the reasons why many wannabe muscle-builders avoid soy protein is because of a belief that soy will increase estrogen and reduce testosterone levels, slowing down muscle growth. A Meta analysis published in a 2010 edition of the journal of "Fertility and Sterility," however, concluded that neither soy-based foods nor supplements have a negative impact on testosterone levels.
Soybeans are the only vegetable food that contains all eight essential amino acids and also eleven non- essential amino acids. Individual amino acids play a role in post exercise muscle recovery. Glutamine and arginine are essential amino acids that help regulate muscle protein balance. Glutamine plays a role in the immune system and is a precursor of glutathione, an antioxidant that protects cells from free radical damage. Arginine, by increasing muscle blood flow, helps bring available nutrients to muscles to speed recovery and may play a role in immune response. Soy protein has about 30% more glutamine and three times more arginine, as compared to whey.
Soy protein is highly digestible as compared to beef, milk, fish, and egg protein in terms of protein quality. In a study the effect of beef versus soy-based textured vegetable protein during resistance training in older men found similar improvements in strength in both the beef and soy groups. By consuming soy-based foods as a source of protein, athletes can keep intake of cholesterol and saturated fat to a minimum, because soy protein is a complete protein that is also low in fat, has no cholesterol and high in fiber.
__Dr. Randhir Hastir