Does high calcium intake cause kidney stones?
About 80% of the time kidney stones are made of calcium, so on the surface it makes sense that calcium intake might cause stones. But studies going back to the 1990s have shown just the opposite: high calcium intake, if it comes from food, makes developing a kidney stone less likely. One possible explanation is that calcium retards the absorption of oxalate, a molecule that often mixes with calcium to cause kidney stones. Oxalate is found in many plant foods, including some varieties of berries, spinach, nuts, and some grains. Several studies have found that calcium supplements, in contrast to calcium from food, are associated with a slight increase in the risk for kidney stones. Researchers have speculated that if people take calcium pills separately from meals, or at just one meal a day (typically breakfast), then calcium may be absent from the gut much of the time and not available for oxalate-blocking duties. Will taking calcium supplements deposit calcium in my arteries? CT scans
