Dietary Calcium and Kidney Stones

Traditional advice to people who have already had one kidney stone has been to cut back on calcium to reduce the risk of another painful episode. New research shows that this common recommendation is misplaced.
Analysis of three large groups of people who have been carefully followed up for decades demonstrates that those who consume more calcium in their diets are about 20 percent less likely to suffer a recurrent kidney stone. The three large cohorts include the Health Professionals Follow-Up Study, the Nurses Health Study and the Nurses Health Study 2, with one million participants among them.
The benefits of dietary calcium are not limited to dairy products. Calcium from sources such as kale or sardines was also protective. Calcium supplements do not appear to provide any similar benefit.
[Journal of Urology, online March 26, 2013]