Many women think that if a certain amount of calcium is good for the bones than even more is better. A large longitudinal and prospective cohort study from Sweden recently showed that consuming more than 700 mg of calcium per day in women older than 63, did not further reduce the risk for fracture or osteoporosis and may, in fact, increase the risk for hip fracture.
This study involved more than 61,000 women between the ages of 63 and 97. During the 19 year period of follow-up on these women, almost 15,000 of them, or about one-quarter, had some type of fracture for the first time. Among those, 3,871, or 6% of them, experienced a hip fracture. Among another subcohort of 5,000 women, 20% of them met the criteria for osteoporosis.
While perhaps surprising to some, the researchers found that the rates of fracture risk were not related to dietary calcium in a linear fashion. It’s true that those women who were in the lowest calcium intake quintile (less than 751 mg/day), had the highest risk for a first time hip fracture, but the group at the next highest risk for hip fracture was the fifth quintile (greater than 1,137 mg per day). A low vitamin D intake made the rate of hip fracture in the lowest calcium quintile group even more pronounced.
Commentary: This is yet one more study that teaches us that more is not always better. In fact in this case, the most was worse. While these results are inconsistent with current U.S. guidelines, I still think it would be a good opportunity to review those guidelines. For women ages 51-70, the Recommended Dietary Allowance (RDA), the intake that meets the needs of 97.5% of the North American population is 1,200 mg per day; the Estimated Average Requirement (EAR)- a number based on the intake that meets the needs of 50% of the North American population, is 1,000 mg per day for women ages 51-70.
Warensjo E, Byberg L, Melhus H, et al. Dietary calcium intake and risk of fracture and osteoporosis: prospective longitudinal cohort study. BMJ. 2011;342:d1473.