DASH Diet May Prevent Kidney Stones

Diets may come and diets may go, but there is one eating plan that has stood the test of time—the DASH Diet. The plan, based on eating whole grains, fruits and vegetables, low-fat and nonfat dairy foods, lean meats, nuts and seeds and foods that are low in sodium, was created nearly two decades ago to help prevent or reduce high blood pressure (DASH stands for Dietary Approaches to Stop Hypertension), but its benefits extend much further. In fact, DASH has been touted the diet for all diseases because it may also reduce the risk of obesity, diabetes, heart disease, osteoporosis, certain cancers, and may help prevent memory loss and sharpen mental skills. And now scientists say the DASH Diet, or an eating plan modeled after it, can also significantly reduce the chances of developing kidney stones.

To determine what effects eating habits have on the formation of kidney stones, Dr. Eric Taylor of the Maine Medical Center, and colleagues at Brigham and Women’s Hospital analyzed the results of three large cohort studies involving more than 241,700 male and female U.S. health care workers who completed surveys about their diets every four years for up to 18 years; 45,821 men in the Health Professionals Follow-up Study, 94,108 older women in the Nurses’ Health Study I, and 101,837 younger women in the Nurses’ Health Study II. The participants were assigned scores based on how well they adhered to eight components of the DASH Diet; increased intake of fruits, vegetables, nuts, legumes, low-fat dairy products, and whole grains, and low intake of sodium, sweetened drinks, and red and processed meats.

Over a combined 50-year follow-up period, a total of 5,645 kidney stones developed in the participants. Those with the highest DASH scores were between 40 and 45 percent less likely to develop kidney stones than those with the lowest scores. The reductions in kidney stone risk were independent of age, gender, body size, fluid intake, and other factors. “Consumption of a DASH-style diet is associated with a marked decrease in kidney stone risk,” the authors said. “The impact was similar in men and women, in older and younger individuals, and in participants with both low and high body mass index.”

The team theorizes the decreased risk could be due to the fact that consumption of fruits and vegetables increases urinary citrate, which inhibits calcium stone formation. Also, a diet with normal or high calcium intake and low intake of animal protein and sodium decreases the risk of stone formation. They say the findings question the wisdom of recommending certain dietary restrictions to patients with kidney stones. “Although we think it reasonable for calcium oxalate stone formers with high levels of urinary oxalate to avoid intake of some individual foods very high in oxalate (such as spinach and almonds), our data do not support the common practice of dietary oxalate restriction in calcium stone formers, particularly if such advice results in lower intake of fruits, vegetables, and whole grains,” the authors said.

The authors also say the findings make a case for a randomized clinical trial of dietary intervention to prevent kidney stones, given the adverse side effects of many medical therapies for the condition.  

The study has just been published in the Journal of the American Society of Nephrology.