Both High, Low Levels of Vitamin D in Older Women May Be Problematic

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THURSDAY, Dec. 9 (HealthDay News) Both low and high levels of vitamin D are associated with increased risk of frailty in older women, a new study finds.

Researchers measured vitamin D levels and assessed frailty in thousands of women aged 69 and older. The risk of frailty was lowest among women with vitamin D levels between 20 nanograms and 29.9 nanograms per milliliter and highest among women with vitamin D levels less than 20 ng/ml and more than 30 ng/ml.

The study has been accepted for publication in the Journal of Clinical Endocrinology & Metabolism.

Vitamin D deficiency and frailty are common with aging. Many experts recommend monitoring vitamin D levels in older adults and prescribing vitamin D supplementation if levels are less than 30 ng/ml. But these study findings raise questions about that practice.

"Vitamin D supplementation has grown in popularity, yet the association between vitamin D status and risk of adverse health outcomes in older adults is uncertain," lead author Dr. Kristine Ensrud, a professor of medicine and epidemiology at Minneapolis VA Medical Center and the University of Minnesota, said in an Endocrine Society news release.

The industry-sponsored Vitamin D Council, in fact, recommends a "minimal acceptable" blood level of 50 ng/ml. But, Ensrud noted, "Our study did not find that higher vitamin D status [more than 30 ng/ml] was associated with lower subsequent risks of frailty or death. In fact, higher levels of vitamin D were associated with increased likelihood of frailty."

"Our results indicate that well-designed large randomized trials of sufficient duration are needed to accurately quantify health effects of vitamin D supplementation, including whether or not supplementation reduces the incidence or progression of frailty in older adults," Ensrud concluded.

-- Robert Preidt

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SOURCE: The Endocrine Society, news release, Dec 8, 2010