Calcium/Vitamin D Supplementation Study Fact Sheet

WHAT IS THE PURPOSE OF THE CALCIUM/VITAMIN D (CAD) SUPPLEMENTATION STUDY?

Previous research on calcium/vitamin D and its effect on bone fractures is limited. Past research in this area is observational and focused more on bone mass than the frequency of bone fractures. Observational studies also suggest that increased calcium and vitamin D intake may decrease the risk of colorectal cancer.

The calcium/vitamin D study will test whether these supplements reduce the risk of colorectal cancer and the frequency of hip and other bone fractures in postmenopausal women.

HOW WILL THE CAD STUDY BE CONDUCTED?

Women in the hormone replacement therapy and/or the dietary modification clinical trials will be encouraged to also join the CaD study at their first and second annual visits.

About 45,000 postmenopausal women aged 50-79 will be randomized into one of two study groups. One group takes 1,000 mg of calcium carbonate and 400 International Units of vitamin D daily. The second group takes a placebo. Women who already take calcium supplements can continue to take them. Participants will be followed for 7 to 11 years for this part of the study and contacted by their clinical center every six months to assure their safety and assess their health.