The Jury is Still Out on the Health Benefits of Vitamin D

Low blood levels of vitamin D are linked to several diseases and may increase risk of death from cardiovascular disease and cancer, but firm universal conclusions about its benefits cannot be drawn. Unfortunately, taking supplements to raise vitamin D levels, may not necessarily be the answer, two new studies conclude, according to the British Medical Journal.

For the past few years, vitamin D has been gaining a reputation as a wonder vitamin that offers protection against some cancers, bone-weakening osteoporosis, heart attack, Alzheimer’s disease, and other chronic conditions.

Not so fast, caution the new studies. In one study, researchers at the University of Edinburgh found that “universal conclusions about the benefits of vitamin D supplementation cannot be drawn” and say further studies and better-designed trials are needed. They evaluated the results of 268 previous studies of vitamin D.

Their results also cast doubt on the effectiveness of vitamin D-only supplementation for osteoporosis and / or prevention of falls. This suggests that vitamin D “might not be as essential as previously thought in maintaining bone mineral density,” they wrote.

Of a remarkable positive 137 different health outcomes reportedly linked to vitamin D, they found that only 10 had been thoroughly tested in trials, and only one (birth weight – linked to a mother’s vitamin D levels in late pregnancy) had evidence of “benefit.” 

Bottom line: the researchers failed to find any convincing evidence of a clear role of vitamin D supplements for improving health outcomes.

“For now, the vitamin D story is intriguing,” said Naveed Sattar, a professor of metabolic medicine at the University of Glasgow in Scotland, said in an editorial accompanying the studies. But more research is required before any definitive recommendations should be made, he said, since “there may yet be unexpected risks to supplementation.”

Vitamin D3 Supplementation Confers Possible Benefit

Another study offers a different perspective, suggesting that the type of vitamin D included in the supplements may make a difference. Researchers at the University of Cambridge and the Erasmus Medical Center showed that low blood levels of vitamin D are linked to increased risks of dying prematurely from cardiovascular disease, cancer, and other causes.

Significantly, they found that vitamin D3 supplementation reduced overall mortality by 11 percent, whereas D2 supplementation did not. 

The studies underscore the need for further research and better designed trials before further conclusions are drawn. In the meantime, if you are unable to keep blood levels of vitamin D high enough via sun exposure alone, you may be better off taking D3 versus a generic vitamin D supplement.

“I think most people would benefit from vitamin D3 supplements unless you’re getting a lot of sunshine,” says Dean Ornish, MD, founder and president of the non-profit Preventive Medicine Research Institute and Clinical Professor of Medicine at the University of California, San Francisco following the release of the two reports.