Help your kidneys: Pass on salt and diet soda

Study shows diets high in sodium and artificially sweetened soda linked to kidney function decline.

Individuals who consume a diet high in sodium or artificially sweetened drinks are more likely to experience a decline in kidney function, according to two papers being presented at the American Society of Nephrology's annual meeting in San Diego, California.

Julie Lin MD, MPH, FASN and Gary Curhan, MD, ScD, FASN of Brigham and Women's Hospital studied more than 3,000 women participating in the Nurses' Health Study to identify the impact of sodium and sweetened drinks on kidney function.

"There are currently limited data on the role of diet in kidney disease," said Dr. Lin. "While more study is needed, our research suggests that higher sodium and artificially sweetened soda intake are associated with greater rate of decline in kidney function."

The first study, "Associations of Diet with Kidney Function Decline," examined the influence of individual dietary nutrients on kidney function decline over 11 years in more than 3,000 women participants of the Nurses' Health Study. The authors found that "in women with well-preserved kidney function, higher dietary sodium intake was associated with greater kidney function decline, which is consistent with experimental animal data that high sodium intake promotes progressive kidney decline."

The second study, also conducted by Dr. Lin and Dr. Curhan, "Associations of Sweetened Beverages with Kidney Function Decline," examined the influence of sugar-sweetened and artificially sweetened beverages on kidney function decline in the same group of Nurses' Health Study participants. An analysis of the nationally representative NHANES III participants had previously reported an association between sugar-sweetened soda and urinary protein, but data on kidney function change was not available. This investigation reported "a significant two-fold increased odds, between two or more servings per day of artificially sweetened soda and faster kidney function decline; no relation between sugar-sweetened beverages and kidney function decline was noted" said Dr. Lin. This association persisted even after the study authors accounted for age, caloric intake, obesity, high blood pressure, diabetes, cigarette smoking, physical activity, and cardiovascular disease. The mechanisms for kidney decline in the setting of high intake of artificial sweetenters have not been previously studied and deserve further investigation.