That whey - protein shake you chug after a workout does more than build muscle. According to a new study from Ohio State, whey protein may help protect the body from prostate cancer. The reason? Whey is a good source of cystein, one of the major building blocks of a prostate - cancer - fighting antioxident called glutathione. By adding even small amount of whey to your diet, say researchers, you may be able to increase glutathione levels in your body by up to 60 percent - making it easier for prostate cells to fight off disease.