Calcium has often been promoted for building strong bones and preventing fractures.  However, reports from the Women’s Health Initiatives, which studied 36,282 women aged 50 and older, indicate this may not be the case.

These women were studied for 7 years with half receiving 1,000 mg of calcium and 400 IU of vitamin D daily and the other half receiving a placebo.  Fracture rates were 12% lower among women receiving the calcium and vitamin D, but the difference was not statistically significant. 

Some researchers concluded that calcium was not helpful in preventing fractures.  In fact, this study also found a small increase in kidney stones (5 or more cases per 10,000 years of study) for people taking extra calcium than people taking the placebo.  However, it is important to keep in mind that, at the beginning of the study, people in the control group were already consuming 1,200 mg of calcium and 400 IU of vitamin daily.  Those taking the supplements were also already getting adequate calcium and took an additional 1,000 mg per day, which raised their intake to 2,200 mg of calcium and 800 IU of vitamin D per day; this is more than is needed.  Therefore, taking the recommended amounts of each should eliminate any increased risk. When people are already getting the recommended amount, taking more is not expected to make much of a difference.

However, certain subgroups had a significant drop in fractures. Among those women taking calcium and vitamin D at least 80% of the time, there was a 21% decrease in hip fractures; furthermore, women at the greatest risk (aged 60 and older) saw a 29% lower risk in hip fractures. 

In addition, a sample of the women also took bone density measurements regularly. These women who took calcium and vitamin D found a significant increase in hipbone density, suggesting stronger bones.

What it Means
Women aged 60 and older will likely have stronger bones by taking calcium and vitamin D daily.  However, taking extra amounts is not necessary for those already getting adequate amounts each day.

Building Bone Health
After interviewing the researchers in this study, the Nutrition Action Healthletter of the New England Journal of Medicine recommends the following for good bone health:

Sources:  Nutrition Acton Healthletter, Behind the Headlines: Calcium & Vitamin D (April 2006), New England Journal of Medicine, 354: 669-683.; National Institutes of Health [news release], Calcium and Vitamin D Supplements Offer Modest Bone Improvement (Feb. 15, 2006); Making Healthy Choices™, Issue 34 (May 2006), Wellsource.