Estimates are that 600,000 Americans have polycystic kidney disease (PKD) which is characterized by the growth of numerous cysts in the kidneys that can eventually lead to kidney failure and the need for dialysis.
In general, eating less protein can help your kidneys, but there's one protein you may want to get a little more of. The results of a study published in the Journal of the American Society of Nephrology in 1999 showed that dietary soy protein can slow the progression of PKD in rats. Rats fed soy as their main protein source had lower kidney weights and fewer cysts compared to those fed casein. (Aukema, Harold M. et al. "Dietary Soy Protein Effects on Inherited Polycystic Kidney Disease Are Influenced by Gender and Protein Level." J Am Soc Nephrol. 10:300-308, 1999). Keep in mind, though, that you'll be better off with traditional fermented soy products like tofu, miso, and tempeh. Non-fermented soy products like soy milk and soy-based protein bars have been shown to cause health problems of their own.
