Calcium and Vitamin D: Big Tablets, Little Yield?

Many view calcium and vitamin D supplementation as a holistic strategy, but data on the effects of longterm supplement use are lacking. Now, in postintervention follow-up of almost 30,000 participants in the Women's Health Initiative (WHI) calcium plus vitamin D trial, researchers evaluated the effects of these supplements on risk for hip and vertebral fracture, as well as for colon and breast cancer (mean postintervention follow up, 4.9 years). Personal use of either supplement at baseline was allowed. During the 7-year intervention phase, women were randomized to daily placebo or 1000 mg calcium carbonate plus 400 IU vitamin D₃.

Although postintervention rates of hip fracture and colorectal cancer were generally similar between groups, a 2…