Is Soy or Whey Protein Better for Muscle Building and Recovery?

Researchers from Indiana University's School of Medicine conclude that soy protein and whey protein are equally beneficial in promoting muscle growth, dispelling a popular but not proven myth that athletes should avoid soy.

The purpose of this study was to compare the response of skeletal muscle protein synthesis (muscle rebuilding) following the ingestion of different protein sources after endurance exercise in rats. Each of the animals was subjected to 120 minutes of treadmill exercise and then fed a carbohydrate-only, carbohydrate and whey protein, or carbohydrate and soy protein meal. The researchers found that soy and whey proteins were equally effective at promoting general muscle rebuilding in the rat's skeletal muscle. Muscle rebuilding was significantly inferior after ingestion of the carbohydrate-only meal.

These findings support a growing body of evidence suggesting soy protein is as effective, and sometimes more effective, than dairy protein in terms of it's ability to promote gaines in lean muscle mass and facilitate muscle recovery after exercise.

Anthony T, McDaniel B, Knoll P, Bunpo P, Paul G, McNurlan M. (2007). Feeding meals containing soy or whey protein after exercise stimulates protein synthesis and translation initiation in skeletal muscle of male rats. Journal of Nutrition, 137: 357-362.