Kidney stones now affect about 1 in 11 Americans—a big increase over the 1 in 20 they affected just 20 years ago.
Who’s at highest risk? White males, according to data from the National Health and Nutrition Examination Survey. Among adults ages 60 and older, 20 percent of men and 10 percent of women have a history of the condition.
What’s the reason behind the uptick in kidney stones? Much of the blame should be placed on the rise of obesity, the survey suggests. Researchers also found an association between kidney stone risk and diabetes and gout. Traditional risk factors for kidney stones include inadequate fluid intake, which results in the production of too little urine; a personal or family history of stones; high blood pressure; and a history of certain types of bowel surgery, such as bariatric surgery or gastric bypass.
Calcium supplements are also associated with a slight risk of kidney stones. However, consuming too little calcium from food can promote kidney stone development.
Since the most common type of kidney stone is formed from calcium combined with oxalate or phosphate, it may seem counterintuitive to eat calcium-rich foods. However, when consumed, calcium binds with oxalate and leaves the body through the stool. When oxalate doesn’t have enough calcium to bind with, it builds up in the bloodstream and enters the urine, where it can cause stones.
In addition to consuming sufficient amounts of calcium (at least two servings a day), take these steps to avoid stones:
• Drink at least eight to 10 cups of fluid a day. Drink enough so your urine is light and clear. Citrus beverages like lemonade and orange juice, as well as citrus-based sodas such as lemon-lime and orange-flavored ones, may also help reduce stone risk.
• Eat a healthy, well-balanced diet. A diet high in animal protein is associated with kidney stone formation, so keep an eye on intake.
• Cut back on salt. Lose excess weight and get regular physical activity. If you’re taking calcium supplements, talk with your doctor about your risk for kidney stones. And take calcium supplements with meals so the mineral better binds with oxalate.
—Reviewed by Brian R. Matlaga, M.D. M.P.H., professor of urology, James Buchanan Brady Urological Institute, Johns Hopkins Medical Institutions, Baltimore.