Whey Versus Soy Protein Diets and Renal Status in Rats

The authors would like to thank Jonatan Ruiz for his constructive comments on the manuscript. This study was supported by the project DEP2008-04376 from the Ministry of Science and Innovation and grants from the Spanish Ministry of Education (AP2009-5033, AP2009-3173).Different dietary protein sources can promote different renal statuses. We examined the effects of whey protein (WP) and soy protein (SP) intake on plasma, urinary, and morphological renal parameters in rats. One hundred and twenty Wistar rats were randomly distributed into 2 experimental groups fed with either WP or SP diets over 12 weeks. These diets were based on commercial WP or SP isolates. The urinary calcium content was higher in the WP diet compared to the SP diet group (P < .001) whereas the urinary citrate level was lower (P < .001). The urinary pH was more acidic in the WP diet group compared to the SP diet group (P < .001); however, no differences were observed between the groups for any of the renal morphological parameters analyzed (all, P > .05) or other plasma renal markers such as albumin or urea concentrations. The increase of acid and urinary calcium and the lower urinary citrate level observed in the WP diet group could increase the incidence of nephrolithiasis compared to the SP diet group. Despite the WP showed poorer acid-base profile, no significant morphological renal changes were observed. These results suggest that the use of SP instead of WP appears to promote a more alkaline plasma and urinary pro le, with their consequent renal advantages.Ministry of Science and Innovation DEP2008-04376Spanish Ministry of Education AP2009-5033, AP2009-317