Supplementation with calcium and Vitamin D is routinely recommended to prevent osteoporosis and bone fractures in postmenopausal women. Taking calcium increases calcium in the blood, making more available for uptake into the bone. With normal aging, there is a decrease in calcium absorption by the stomach. Vitamin D is known to increase calcium absorption in the gut, as well as acting synergistically with calcium to promote bone density. This has led to the common practice of prescribing calcium and Vitamin D supplementation for the prevention of hip fractures. It sounds so good and all makes logical sense, and it can not hurt, so why not go ahead and do it?
However, just because you become deficient in something with aging, does not mean that supplementation will correct the problem. Studies have shown that calcium and vitamin D supplementation in people over age 65 increased total bone density, but not necessarily in areas that matter, like the femoral neck, which causes hip fracture. The only studies which showed that calcium and Vitamin D prevented hip fractures were done in French women who had osteoporosis and were living in nursing homes. However these women may have calcium and / or Vitamin D deficiency due to diet or lack of sunlight from being in a nursing home.
Other studies in individuals outside nursing homes found no beneficial effects from Vitamin D and calcium supplementation in terms of hip fracture prevention. One study of patients who had a fracture and became immobile did not find any benefit of Vitamin D and calcium in the prevention of secondary fractures. The Women's Health Initiative (WHI) study included 36,282 premenopausal women age 50 to 79 who were randomly assigned to receive 1000 mg of calcium with 400 IU of Vitamin D-3 or placebo with a follow-up of 7 years for assessment of bone fracture. Supplementation did not reduce the risk of hip fracture. Although there was an increase in hip bone density, there was also an increase in kidney stones. Since increasing hipbone density has no practical benefit and is not related to reducing the risk of hip fracture, while increasing kidney stones is definitely negative, there is no reason to take these supplements.
Bottom line? Take a walk in the sun, and eat a balanced diet with lots of greens and vegetables to get your calcium fix.