Thursday July 24, 2014 (foodconsumer.org) -- Researchers at the University of Granada in Granada, Spain conducted a study and found some evidence suggesting that soy protein may be friendlier to the kidney than whey protein.

Dietary protein sources can influence the renal status.  In the study, rats were fed for more than 12 weeks a diet either with whey protein or soy protein both of which were purchased from the market. 

More calcium was excreted from rats fed on the whey protein diet, compared with rats fed on the soy protein diet.  And the urinary pH was found lower in the rats fed on the whey protein diet, compared with rats on the soy protein diet.

However, no differences were observed between the two groups in renal morphologic parameters or other plasma renal biomarkers like albumin or urea.

The researchers explained that the elevated level of acid and calcium in the urine and the lower urinary citrate level in the rats on the whey protein diet indicated that the whey protein eating rats were more likely to develop nephrolithiasis than those eating soy protein.

The study concluded “These results suggest that the use of SP (soy protein) instead of WP (whey protein) appears to promote a more alkaline plasma and urinary profile, with their consequent renal advantages."

Whey protein isolates and soy protein isolates as dietart supplements can be used to build muscle.  They are popular sports supplements.

Comment:  With a lower pH, a person can be at higher risk of developing kidney stones.  This low pH problem can be easily solved by taking potassium citrate.  Studies have shown that taking potassium  citrate for a few days get rid of kidney stones completely.  (David Liu)

Reference: Aparicio VA, Nebot E, Tassi M, Camiletti-Moirón D, Sanchez-Gonzalez C, Porres JM, Aranda P.  Whey Versus Soy Protein Diets and Renal Status in Rats.  J Med Food. 2014 Jul 23.