Osteoporosis: Do Vitamin D & Calcium Supplements Really Prevent Fractures?

Healthy postmenopausal women may want to cross off the calcium and vitamin D supplements from their shopping list, according to research by the U.S. Preventive Services Task Force reported in the Huffington Post.  

Reviewing all the studies available, researchers found that healthy postmenopausal women should not take the low recommended doses of vitamin D and calcium supplements to protect against osteoporosis-related bone fractures.

Confused? You’re not alone. For decades, the standard recommendation from medical providers has been to take 400 IU of vitamin D and 1,000 mg of calcium to prevent osteoporosis. But according to Dr. Kirsten Bibbins-Domingo, an associate professor of medicine at the University of California in San Francisco, “It is clear that lower doses of calcium and vitamin D do not prevent fractures,” she told the New York Times, “and there is a small but measurable risk of kidney stones.”

The task force, which is comprised of an independent panel of medical professionals that have been appointed to the U.S. Department of Health and Human Services, analyzed data from 137 clinical studies that investigated vitamin D’s role in osteoporosis-related fractures in postmenopausal women, fractures in men and in premenopausal women, and in cancer prevention of the breast, prostate and colon.

The task force concluded that there is insufficient evidence that calcium and vitamin D prevent cancer or help prevent fractures in men and in premenopausal women.

And when it comes to preventing osteoporosis-related fractures in postmenopausal women, the task force found the strongest evidence of all: that not only is there insufficient proof that vitamin D and calcium are helpful, but that there is strong evidence that they do not help prevent osteoporosis-related fractures in healthy postmenopausal women.

The strongest evidence from the studies showed that not only is there is insufficient proof that vitamin D and calcium are helpful for postmenopausal women, but there was sufficient evidence that they do not help prevent osteoporosis-related fractures in postmenopausal women.

Dr. Ethel Siris, director of Columbia University’s osteoporosis center, said she and other osteoporosis experts were already aware that the supplements do not prevent fractures. Even so, some doctors believe that the research has only proven the ineffectiveness of these supplements at low doses, and that at higher doses, vitamin D and calcium may still help to prevent cancers and osteoporosis-related fractures.

According to the task force report, vitamin D regulates bone mineralization and influences other tissues. The two forms of vitamin D—cholecalciferol (D3) and ergocalciferol (D2)—are both activated in humans by sunlight—first in the liver and then in the kidneys, to form what doctors call blood 25-(OH)D, which affects hormones, insulin, immunity and cell activities. These effects are why researchers have been studying the use of vitamin D in cancer prevention. But in this case, the task force concluded that there was not enough evidence to support the claim that vitamin D and calcium have any correlation to cancer risk—either for or against.

The survey observed that studies in this area are hindered by incomplete nutrient databases for vitamin D-fortified foods and vitamin D supplements, while there are no methods to ascertain vitamin D synthesis from sunlight. Because we don’t have a way to figure out how much is naturally absorbed from diet and sunlight, it is difficult to know how much to supplement. The conclusion of the task force study reiterated that further study is needed to determine proper dosing recommendations.

Don’t just forget about your vitamin D and calcium needs altogether, however. Vitamin D and calcium are still important for health. According to Molly Lee, founder and director of holistic health and nutrition practice EnergizingNutrition.com, humans need 5 to 30 minutes of sunlight per week. But if that is not possible, vitamin D can be found in sardines, eggs and cod liver oil. Symptoms of a vitamin D deficiency can include muscle pain, bone fractures and depression.

Vitamin D also aids in the absorption of calcium. The best sources of bioavailable calcium include dark leafy greens, legumes, tofu, fish and dairy products. The survey concluded that people with a varied, healthy diet and moderate outdoor activity should be getting enough calcium and vitamin D.

But people that live in nursing homes, those undergoing drug treatments that drain mineral and vitamin resources, and those who do not have adequate diet and sunlight may still need to take vitamin D and calcium supplements, under the direction of their doctor.

Source: Vitamin D With or Without Calcium Supplementation for Prevention of Cancer and Fractures: An Updated Meta-analysis for the U.S. Preventive Services Task Force, Mei Chung, PhD, et.al.

Huffington Post Healthy Living, June 2012