Kidney Stones - Other Treatments

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Role of Calcium

Calcium from Foods. Dietary calcium recommendations for kidney stone prevention need to be determined on an individual basis. A doctor will suggest calcium guidelines based on a patient’s age, gender, body size, and type of stone. Most studies indicate that dietary calcium (found in milk, yogurt, and cheese) protects against many types of calcium oxalate stones. Large studies of both men and women found that those with the highest intake of calcium from foods had a much lower risk for stones than those who had little calcium in their diets. A diet containing a normal amount of calcium, but reduced amounts of animal protein and salt, may protect against stones better than a low-calcium regimen. However, calcium metabolism changes as people age. Some studies suggest that a high calcium intake protects against kidney stones in men younger than age 60, but not in older men.

Dietary calcium may actually bind the oxalate in foods, preventing it from being absorbed into the blood and excreted into the urine. In a normal healthy diet, dairy products supply almost 80% of the daily calcium requirement. For people have calcium stones associated with resorption (the breakdown of bone that releases calcium into the bloodstream), limiting calcium intake could cause further bone loss.

Calcium Supplements. Evidence on calcium supplements is mixed, although in general many studies suggest that they reduce oxalate levels and so help prevent calcium oxalate stones. One study suggested that taking 500 mg of calcium supplements a day regularly may "reprogram" the intestines to absorb less calcium and so be protective. Experts generally advise that calcium supplementation within dosage recommendations, approximately 1,200 mg per day, remains safe. In one study, however, women who took calcium supplements had a 20% higher risk for stones. Research indicates that dosages of calcium above 2,000 mg per day are clearly associated with the formation of stones. Some experts speculate that this higher risk may occur because supplements are often taken in the morning, either without food or with breakfast, which is typically low in oxalates. Taking supplements with later meals may not incur the same risk.