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Is it safe for the kidney? Low-carb, high-protein versus low-fat diets

Lead author Allon N. Friedman, M.D., associate professor of medicine at Indiana University School of Medicine, said, “Low-carbohydrate, high-protein diets have been popular for decades, despite persistent concerns that they may lead to kidney damage or even failure. Our study results help allay some of these concerns.”

The study, from 2003 to 2007, enrolled 307 obese adults without serious medical illnesses at three academic medical centers in the United States. The study subjects, all between the ages of 18 and 65, were randomly assigned to a low-carbohydrate, high-protein diet or a standard low-fat weight-loss diet for 24 months. Weight loss between the two groups did not differ. The researchers looked at a number of indicators of kidney health and function, including kidney filtration, protein loss in the urine, and blood and urine electrolytes.

“The results indicate that healthy obese individuals on the low-carb, high-protein diet did not experience changes that could be perceived as harmful even after being on the diet for two years,” Dr. Friedman said. “The findings suggest that the diet does not harm the kidneys of obese patients who are otherwise healthy. However, we need more research to determine whether this finding holds true for patients with pre-existing diabetes, hypertension or kidney disease.”

The eJournalClub article is available to American Society of Nephrology members and nonmembers. The editor’s choice is based on several factors, including that the original research article must be of wide interest to nephrologists and the public.