Calcium and vitamin D supplements in healthy postmenopausal women provide a modest benefit in preserving bone mass and prevent hip fractures in certain groups including older women but do not prevent other types of fractures or colorectal cancer, according to the results of a major clinical trial, part of the Women's Health Initiative (WHI).
The study results are published in the current issue of The New England Journal of Medicine.
"This important study provides guidance for women on the risks and benefits of supplementing their diets with calcium and vitamin D. The overall results suggest that women, particularly those over 60, should consider taking calcium and vitamin D for bone health but they should not expect these supplements to help prevent colorectal cancer," said Elizabeth G. Nabel, M.D., NHLBI director and director of the Women's Health Initiative.
The WHI Calcium with Vitamin D (CaD) trial of 36,282 postmenopausal women ages 50 to 79 found a small but significant 1 percent higher hip bone density for those taking calcium combined with vitamin D compared to those taking placebo.
During the trial, 374 women had hip fractures with a fracture rate of 14 per 10,000 cases per year in the supplemented group compared to 16 per 10,000 per year in the placebo group.
This 12 percent reduction in hip fracture in those taking the calcium plus vitamin D supplement was not statistically significant; however, women who consistently took the full supplement dose experienced a significant 29 percent decrease in hip fracture.
Women older than 60 had a significant 21 percent reduction in hip fracture. The supplements had no significant effect on spine or total fractures.
Calcium/vitamin D supplements provided no detectable effect on the incidence of colorectal cancer. There were similar rates of cancer in both the calcium/vitamin D and placebo groups (13 cases per 10,000/year compared to 12 cases per 10,000/year respectively).
