For most people, the evidence doesn’t support any bone benefit of the popular supplements.
The U.S. Preventive Services Task Force (USPSTF), an independent group of health experts, reviewed research on the role of vitamin D and calcium supplements in preventing fractures, and found that adding 400 IU of vitamin D and 1000 mg of calcium to a healthy diet does not lower risk of fractures in post-menopausal women, and that for younger women and for men, the studies are too inconclusive to support regular use of the supplements.
“It’s important to keep in mind that the presumption is that the people we are talking about here do not have known bone disease, they don’t have osteoporosis and they are not vitamin D deficient,” says the task force chair Dr. Virginia Moyer, a pediatrics professor at Baylor College of Medicine. “This is supplemental, so this is above and beyond getting what the expert consensus is for what you should be getting everyday.”
To come up with its recommendations, published in the the Annals of Internal Medicine, the Task Force commissioned two reviews of the available studies to date on the subject and a meta-analysis on vitamin D supplementation with or without calcium to investigate the association of vitamin D and calcium levels on bone health as well as the adverse effects of taking the pills.
The task force concluded there isn’t enough evidence to show that getting more vitamin D and calcium than what healthy people get from their diet, and from healthy exposure to sunlight, which prompts vitamin D formation, offers much of a benefit. “Unfortunately for the studies that are out there, they have the regretable problem of having a wide variety of patient populations and a variety of doses. At the beginning it looks like there’s a lot of information, but actually there is a little bit of information here, and a little bit there, which is very hard to combine,” says Moyer.
The task force is recommending against daily supplements of less than 400 IU of vitamin D and less than 1,000 mg of calcium for preventing fractures in postmenopausal women. “We are making it clear that using relative low doses is ineffective, but I think that is kind of known already,” says Moyer.
On the other hand, the panel concluded that there was not enough evidence to make a recommendation on daily supplements greater than 400 IU of vitamin D and 1,000 mg of calcium for preventing fractures in postmenopausal women. At higher doses, however, come potential risks. Some studies showed that too much vitamin D and calcium can increase the risk of kidney stones and other conditions.
The results are the latest in a string of recommendations from the USPSTF that appear to reverse medical advice; the task force previously recommended that men no longer get regular prostate specific antigen (PSA) testing to detect prostate cancer, and that women delay routine mammogram screening until they are 50 years old. The apparent about-faces are based on a more solid review of the risks and benefits involved, however, and represent the best evidence to date on the issue. As far as vitamin D and calcium are concerned, the panel members are not denouncing the potential benefit of these compounds in keeping bones healthy. They”re just advising people that adding extra supplements may not avoid additional fractures. “We are not saying, ‘don’t get your daily requirement.’ We are just looking at whether there is any benefit to adding a bunch of stuff on top of your daily requirement,” says Moyer.
The task force is recommending that more research be done to address the inadequate evidence. “Physicians and patients need to make decisions based on the best available evidence they can find. Keep in mind that vitamin D and calcium are over-the-counter medications, and quite frequently physicians don’t even know their patients are taking these things. It’s good for your physician to actually know what you are taking because there is always a possibility that it could interact with something else your taking. Even if what you’re taking to you seems like nothing more than a nutritional supplement,” says Moyer.
The task force remains behind its previous bone health recommendations that women age 65 and older and younger women at high risk for fractures be screened for osteoporosis. It also recommends vitamin D supplements to prevent falls in community-dwelling adults age 65 and older who are at an increased risk for falls, like those with a vitamin D deficiency or those who have fallen previously.