Pietro Manuel Ferraro, MD, physician, department of internal medicine and medical specialties, Catholic University of the Sacred Heart, Rome, Italy. His study was published in Clinical Journal of the American Society of Nephrology.
Mention kidney stones and everyone within earshot winces—because we’ve all heard how painful these stones can be. So if you want to be stone-free, you’re probably following the common advice to drink lots of liquids. But instead of focusing on how much you drink, the crucial question is what you drink, a new study reveals. Certain beverages—including some very surprising ones, such as beer!—are particularly helpful in protecting against stones, while other drinks do more harm than good.
Unfortunately, kidney stones are common, plaguing 19% of men and 9% of women in the US at least once in their lifetimes—and recurrences are quite common. Drinking plenty of water helps prevent stones from forming…but actually, there are other fluids that can be even more effective.
Using data from three large studies, researchers followed 194,095 people, none of whom had a history of kidney stones, for more than eight years. Participants periodically completed questionnaires about their diet and overall health. During the course of the study, there were 4,462 cases of kidney stones.
Researchers adjusted for health factors (age, body mass index, diabetes, medications, blood pressure) as well as various dietary factors (including intake of meat, calcium and potassium) known to affect kidney stone risk. Then they calculated the stone risk associated with various types of beverages.
How the comparison was done: For each analysis, the effects of drinking an average of one or more servings per day were compared with drinking less than one serving per week. Because data from three different studies were used, serving sizes were not necessarily alike across the board. But in general, a serving was considered to be 12 ounces of soda or beer…eight ounces of coffee, tea, milk or fruit punch…five ounces of wine…and four to six ounces of juice. The researchers’ findings were eye-opening.
Kidney stone risk boosters…
Kidney stone risk reducers…
Consumption of milk and juices other than orange juice did not significantly affect the likelihood of developing kidney stones.
Theories behind the findings: Because sugar-sweetened sodas and fruit punch are associated with higher risk, researchers suspect that their high fructose concentration may increase the amount of calcium, oxalate and uric acid in the urine—and those substances contribute to kidney stone formation. So how to explain the beneficial effects of orange juice, which is also high in fructose? Perhaps orange juice’s high concentration of potassium citrate offsets the fructose and favorably changes the composition of urine.
Regarding the beneficial effects of coffee and tea, it could be that their caffeine acts as a diuretic that promotes urine production and thus helps prevent stones. Tea and coffee, including decaf, also contain antioxidants that may help combat stone formation. Alcohol, too, is a diuretic, and wine and beer contain antioxidants as well—though of course, with any type of alcoholic beverage, moderation is important.