According to researchers at Stanford University Medical Center, older women who regularly take calcium and Vitamin D marginally decrease their risk of hip fractures.
However this is not the case when it comes to other types of fractures or colorectal cancer, and in fact increases their risk of getting kidney stones.
The latest findings from the Women's Health Initiative study, a 15-year, broad-based look at the causes and prevention of diseases affecting older women, found such supplements slightly increased the incidence of kidney stones.
Previous WHI studies have involved hormone therapy, low-fat diets and heart disease.
Marcia Stefanick, PhD, professor of medicine at the Stanford Prevention Research Center, says current recommendations that women over age 50 should consume 1,200 milligrams of calcium and 400-600 international units of Vitamin D each day to maintain their bone health, are still relevant, but suggests that adequate levels of these nutrients should come through the food eaten.
The study of 36,282 postmenopausal women between the ages of 50 and 79, who were tracked over the course of seven years, concluded that the treatment did not prevent broken bones of any kind and is based on assessments of all the women who participated.
It seems that 20 percent of the volunteers did not take the tablets regularly, and the supplements appeared to reduce the risk of a broken hip by only 29 percent for those who stuck to the treatment over most of the seven-year study.
However according to the research, the supplements did not reduce the likelihood of spine, wrist or other types of fractures, and they increased the risk of kidney stones by 17 percent.
A greater benefit was expected as Americans spend an estimated $993 million a year on calcium supplements to ward off osteoporosis, a disease in which bones become fragile and more likely to break.
In the study, half of the volunteers received 1,000 milligrams of calcium carbonate along with 400 international units of vitamin D, while the others were given placebos.
Calcium and Vitamin D have long been staples in the effort to improve bone health among older women, who are four times more likely than men of the same age to suffer from osteoporosis - a disease in which bones become fragile and more likely to break.
The condition contributes to 1.5 million fractures each year in the United States, including more than 300,000 hip fractures.
Forty percent of women over age 50 experience a fracture of the hip, spine or wrist in their lifetime.
Additionally, some observational studies have suggested that a higher intake of calcium and Vitamin D could lower the risk for colorectal cancer, but results from past clinical trials have been mixed.
Colorectal cancer is the second-leading cause of cancer deaths in the United States for men and women combined.
Stefanick says the results show that women should continue to make sure they get enough calcium and Vitamin D for their bone health, but that they should not expect this to make a difference in preventing colorectal cancer.
Stefanick says that early detection through regular screenings for colorectal cancer should be emphasized for both women and men from age 50 onward.
The findings are published in the current issue of the New England Journal of Medicine.