Weight loss. Bone health. Breast cancer prevention. Taking vitamin D and calcium may help with all of the above, according to several recent studies.

For instance, researchers found that postmenopausal women who took a daily combination of calcium and vitamin D weighed, on average, about a quarter-pound less than those who took a placebo (Archives of Internal Medicine, 2007, vol. 167, no. 9).

In another study published in the Journal of Clinical Endocrinology & Metabolism (2007, vol. 92, no. 4), Belgian researchers analyzed previous trials of postmenopausal women and men over 50. People who took both vitamin D and calcium reduced their risk of hip fracture by 18 percent (see Bone boost for more information on bone health).

Finally, Harvard Medical School scientists found that premenopausal women who took the most calcium and vitamin D had a 39 percent and 35 percent reduced risk, respectively, of breast cancer compared with women with the lowest intake (Archives of Internal Medicine, 2007, vol. 167, no. 10).

"Many people are vitamin D–deficient, particularly those with limited sun exposure," explains Susan Harris, DSc, a nutritional epidemiologist at the Friedman School of Nutrition at Tufts University. "Everyone should aim for 1,000 IU per day of vitamin D," she says. For calcium, three to four daily servings of dairy should get you the recommended 1,200 mg (1,000 mg for adults under 50). If you need additional calcium supplementation, Harris advises splitting the dose throughout the day (not more than 500 mg at a time) for best absorption.