Which is best? Soy protein or whey?

When it comes to building muscles, which is best, soy protein or whey? Body builders both use soy and whey protein to aid in the development of muscle mass. Though the proteins have a similar effect on the body, there are subtle differences. To determine which protein works best for your fitness program, consider the benefits and side effects of each substance.

Whey Protein

Whey protein comes from cow's milk. This high quality protein is considered complete because it contains all the essential amino acids. Whey is also the best source of the branched chain amino acids: leucine, isoleucine and valine. The branched chain acids are invaluable to athletes because the body takes these acids from the muscles during exercise. Whey protein is also known to help weight loss by increasing muscle mass, accelerating the metabolism and creating a sensation of fullness. In addition to these benefits, whey has a high absorption rate which means that it begins rebuilding muscles very quickly after its ingested.

Whey does have a few disadvantages. Because it is milk protein, people with diary allergies should avoid it. Whey's quick absoprtion rate means you don't have to wait as long between workouts. This also means that your muscles have lest time to rest. Therefore, while whey is highly effective in rebuilding muscle, it's less effective in building new muscle.

Soy Protein

Soy is a plant based protein that comes from soy beans. Like whey, it is considered a complete protein and contains all the essential amino acids. While whey is rich in the branch chained amino acids, soy is rich in both arginine and glutamine. Arginine helps muscle formation. Soy has a slower absorption rate than whey which means it takes the body longer to digest the protein. Therefore, soy is less helpful in rebuilding muscle, but extremely helpful in forming new muscle tissue. Because soy is plant based, it is a great alternative to whey protein for those dealing with diary allergies.

There are some concerns about the isoflavones found in soy. Studies suggest that isoflavones can disrupt the body's hormonal balance. As a result soy intake is sometimes implicated in thyriod problems and changes in testosterone and estrogen levels. Also, some of the inhibitors found in soy have been known to obstruct digestion.

Which is Best?

Both whey and soy proteins can help aid in muscle development and growth. Many health scientists now recommend that athlete add a mixture of soy and whey protein to enhance muscle building. Studies show that the combination of both proteins can help release amino acids essential to constructing certain muscle groups. Using both substances can allow you reap the benefits of both proteins.