Why Vitamin D Pills Might Not Work for Some People

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Woman taking supplements vitamins
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Americans are badly in need of more vitamin D. Studies have found that nearly 42% of the U.S. population is deficient in the vitamin.

Many people turn to supplements to get their fix of this nutrient. But a new study suggests that taking these pills is not equally effective for everyone.

Those with a higher body mass index may not metabolize vitamin D supplements in a way that gives them the same health benefit as those who have a lower BMI and take the supplements, according to researchers from Brigham and Women’s Hospital in Boston.

The findings stem from an analysis of the VITAL clinical trial, a Brigham-led effort that looked at whether taking vitamin D or marine omega-3 supplements lowers the risk of developing cancer, heart disease or stroke.

In a press release, first author Deirdre K. Tobias, an associate epidemiologist in Brigham’s Division of Preventive Medicine, says:

“The analysis of the original VITAL data found that vitamin D supplementation correlated with positive effects on several health outcomes, but only among people with a BMI under 25. There seems to be something different happening with vitamin D metabolism at higher body weights, and this study may help explain diminished outcomes of supplementation for individuals with an elevated BMI.”

Vitamin D helps the human body absorb minerals such as calcium and magnesium. People get vitamin D from exposure to sunlight, but that still leaves many people deficient in the vitamin.

It is also believed that vitamin D may influence the incidence and progression of cancer and cardiovascular disease.

In the study, the researchers found that taking vitamin D supplements had a positive impact in people regardless of weight. However, those with elevated BMIs saw less of a benefit.

Commenting in the summary of the study findings, senior author Dr. JoAnn E. Manson, chief of the Division of Preventive Medicine at Brigham and principal investigator of VITAL, says:

“This study sheds light on why we’re seeing 30-40 percent reductions in cancer deaths, autoimmune diseases, and other outcomes with vitamin D supplementation among those with lower BMIs but minimal benefit in those with higher BMIs, suggesting it may be possible to achieve benefits across the population with more personalized dosing of vitamin D. These nuances make it clear that there’s more to the vitamin D story.”

For more on vitamin D and other vitamins, check out:

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