Over the years, I have had a number of patients with painful kidney stones, and once they have passed (or been removed) I have felt at a loss to helping them prevent them. "Stay hydrated" somehow didn't seem adequate, although we know fluid intake can help stave off recurrent kidney stone attacks. Some textbooks said "avoid calcium," since most stones are made of calcium oxalate. High oxalate levels can be found in some fruits and vegetables, as well as in nuts and chocolate. Yet there was no real scientific evidence that these foods caused stones. The evidence for who got kidney stones was all over the ballpark, and, for a physician, that means no prevention advice is really proven.
A new study published in Clinical Journal of the American Society of Nephrology says that calcium-rich foods - such as low-fat milk and yogurt - can be protective. What? Eat more calcium to prevent calcium containing stones? It seems that higher intakes of calcium are actually associated with a reduction in kidney stone risk.
Dietary calcium binds with oxalate, which is a waste product in the digestive system. The two substances crystallize and leave the body long before there is a chance to form a kidney stone.
Dr. Eric Taylor, a renal specialist at Brigham and Women's Hospital in Boston, analyzed the diets of 3,426 people over a long period of time. He found people with higher intake of fruits, vegetables, nuts and legumes, low-fat dairy and whole grains were less likely to develop kidney stones by 40-45%. This is the DASH diet, which is similar to a Mediterranean-style diet, that is the most effective diet for people with high blood pressure.
Like so many things in the body, it is likely a number of factors that intertwine to cause a disorder. But it is always reassuring to find preventative recommendations that we know are healthy and that might prevent a number of problems. Since both hypertension and kidney stones are more prevalent in men over age 40, the DASH diet might be the answer.