Indication: Bone Heath


Source: Am J Clin Nutr, May 2007; 85:1428-1433.

Research:
One hundred and eighty-three women participated in a study to determine whether those who get their calcium from dietary sources have healthier bones compared to those that take mainly supplemental forms of calcium. Researchers asked women to detail their diet and calcium intake for a week; they also tested their bone mineral density and urinary concentrations of estrogen metabolites.

Results:
Investigators found that women could be divided into three groups: the “supplement group” included women who got at least 70% of their calcium from supplement tablets or pills; the “diet group” got at least 70% of their calcium from dairy products and other foods; and those in the “diet plus supplement group” had calcium-source percentages that fell somewhere between the ranges in the first two groups. The “diet group” took in the least calcium, an average of 830 mg per day. Yet this group had higher bone density in their spines and hipbones than women in the “supplement group,” which consumed over 1000 mg per day. Women in the “diet plus supplement group” tended to have the highest bone mineral density, as well as the highest calcium intake at 1620 mg per day. The hormone estrogen is known to maintain bone mineral density. But the standard form of estrogen is broken down or metabolized in the liver to other forms—some active and some inactive. Urinalysis showed that women in the “diet group” and the “diet plus supplement group” had a higher ratio of active to inactive estrogen metabolites than women in the “supplement group.” Calcium supplements differ in how well their calcium can be absorbed, and this also could play a role in the study’s findings, according to its authors. For example, calcium carbonate tablets need to be taken with a meal so that stomach acid can facilitate absorption, but calcium citrate tablets don’t have this limitation. If the study participants taking calcium carbonate weren’t conscientious about the timing of their supplements, re-searchers believe they might not have received the highest benefit from them.