A large study examined if taking calcium supplements with vitamin D helped prevent bone fractures in healthy postmenopausal women. More than 36,000 women already enrolled in the Women’s Health Initiative project were recruited for this study.
Volunteers were randomly assigned to groups that received daily calcium and vitamin D supplements or placebo pills. Bone density and fracture rate were recorded for up to seven years for each volunteer.
The results indicated a small increase in bone density for the women who took calcium and vitamin D supplements, but no significant decrease in the frequency of hip fractures. In addition, taking the daily supplements did pose a slight increased risk for developing kidney stones.
Dr. Joel S. Finkelstein, an osteoporosis researcher at the Massachusetts General Hospital in Boston, commented in a New York Times article about the study that women have been falsely reassured that supplements would protect them.
"Women come to see me all the time saying, 'How can I possibly have osteoporosis? I exercise and I take calcium and vitamin D,' " he said. "The ads for calcium have given many women the impression that they are protected against osteoporosis," he added.
"The message of the study is that calcium and vitamin D by themselves are not enough," Dr. Finkelstein said. As a therapy to protect against osteoporosis, he said, supplements (alone) are "pretty weak," the New York Times article states. He believes osteoporosis drugs should be considered for patients that actually have osteoporosis.
Jackson, R. et al, 2006. “Calcium plus Vitamin D Supplementation and the Risk of Fractures” NEJM
Kolata, G., 2006. “Study Finds Calcium Supplements Don’t Prevent Broken Bones,” NYTimes. http://www.nytimes.com/2006/02/15/health/15cnd-bones.html?pagewanted=print
Am Dental Assn., 2005. “Vitamin D, Calcium Supplements Do Not Prevent Fractures in Elderly.”