Vitamin D Supplements Don’t Boost Bone Density in Healthy Women

Vitamin D supplements don’t help boost bone density in healthy adults, judging from a review of 23 studies that suggests the supplement should be limited to people with a documented deficiency to fight osteoporosis.

Almost half of adults older than 50 years take vitamin D, researchers led by Ian Reid of the University of Auckland’s Department of Medicine said in an article published in The Lancet medical journal today.

A review of studies encompassing as many as 4,082 patients, most of them women, taking the supplement for an average of two years found little difference in bone density measured at key points in the skeleton such as the hip, the forearm or the lumbar spine. The researchers did note a difference in one place, the femoral neck, but said the benefit didn’t translate elsewhere.

“The negative findings of our analysis contrast with the widely held perception that vitamin D works directly on bone cells to promote mineralization,” the scientists wrote. “This perception is probably incorrect.”

The review comes amid conflicting signals on the nutrient’s health benefits. Researchers last year found that people 65 and older who took 792 to 2,000 units of the vitamin daily had a 30 percent lower risk of hip fractures, supporting a recommendation by the U.S. Institute of Medicine that older people take at least 800 units of the nutrient a day. Doctors often use bone density as a surrogate measure of fracture risk.

A targeted approach to the use of the vitamin would save money that could be used in other areas of health-care, Reid and colleagues wrote in the paper, which belongs to a form of study of research known as a meta-analysis.

The Health Research Council of New Zealand funded the study.

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