Long-term effects of hyperproteic diet on functional renal reserve and natriuresis

Introduction: A hyperproteic diet normally results in acute changes in renal function evidenced by increases of natriuresis and glomerular filtration rate (renal functional reserve). Objectives: To assess the changes in natriuresis and creatinine clearance during 12 weeks on hyperproteic and hypersodic diet. Materials and Methods: Eighteen adults male Holtzman rats were included and the follow-up period was 12 weeks. The rats were initially distributed into three groups; hyperproteic diet (30%) from an animal source (n=6), hyperproteic diet (30%) from a plant source (n=6) and normoproteic diet (18%) from an animal source (n=6). The diets were isocaloric, normosodic (0.25%). From week 8, each group was divided into three rats each and received a high-sodium (1.5%) and normosodic diet (0.25%) respectively. Results: The hyperproteic diet group (animal or plant vegetal source) had higher creatinine clearance than normoproteic diet (P<0.05). The hyperproteic vegetal diet group had a peak with an increased renal functional reserve in 21% (P=0.04). The natriuresis increased in the group on the animal-source diet during the first 2 weeks (P=0.03). The group plant-source diet did not have significant change at the first week (P=0.50); however, there was a subsequent decrease in the level of natriuresis between weeks 3 to 8. When the groups were exposed to a hypersodic diet, there was not difference in the natriuretic response between the groups (P>0.05). Conclusion: A hyperproteic vegetal diet increased renal functional reserve but not natriuresis during an acute or long-term period; however, the natriuretic response was not impaired when a hypersodic diet was added, though hyperfiltration was present.