Calcium Lowers Prevalence of Kidney Stones

Kidney stones might be prevented if younger women increased their calcium intake. The use of calcium supplements, however, has no effect on risk, according to the results of a study reported in the April 26, 2004, issue of the Archives of Internal Medicine. Although an association between dietary calcium and kidney stone risk had been explored in older women and men, there had not been adequate research on this relationship in younger women.

Therefore, the researchers examined data from >96,000 young women who took part in the Nurses' Health Study II. The women had completed dietary questionnaires in the early 1990s and were tracked until a kidney stone was diagnosed, until death occurred, or until May 31, 1999, came. During the follow-up phase of the study, 1223 symptomatic kidney stones were diagnosed.Women with the highest levels of dietary calcium intake were 27% less likely to have developed stones, compared with women with the lowest levels, the researchers reported.

The results further indicated that dietary level of phytate, a salt that contains magnesium and calcium, also was linked with a decreased chance of stone formation. The difference in risk reduction between women with the highest and lowest levels of phytate intake was even greater than that observed with dietary calcium?37%.

The researchers stressed that the results reinforce the idea that "routine restriction of dietary calcium in patients who have had a kidney stone is no longer justified." Furthermore, they said, "dietary phytate may be a new, important, and safe addition to our options for stone prevention."