Lee Swanson Research Update

Study Suggests Optimal Levels of Vitamin D to Avoid Frailty

December 2010

Maintaining adequate levels of vitamin D in the elderly may be clinically important for reducing the risk of frailty.

A study with 4,551 women of at least 69 years of age indicated that blood levels of vitamin D between 20.0 and 29.9 ng/ml are at the lowest risk of frailty, while levels above or below this range are associated with an increased likelihood of frailty in older women, according to findings published in the Journal of Clinical Endocrinology & Metabolism (JCEM).

In an accompanying editorial in the same journal, Clifford Rosen, MD (Maine Medical Center Research Institute) and JoAnn Manson, MD, DrPH (Brigham and Women's Hospital and Harvard Medical School) said the findings are consistent with other observational studies that "imply that optimal serum 25-OH D concentrations for preventing frailty range between 20 and 30 ng/ml."

Importantly, Rosen and Manson note the number of individuals with blood vitamin D levels over 30 ng/ml was relatively small, with the mean level of vitamin D measured as 23.2 ng/ml.

"The dose-response relationship, presence or absence of a threshold, and the possibility of harm at both lower and higher levels of vitamin D intake, require further study, particularly with randomized controlled trials," wrote the Boston-based scientists.

"In the meantime, the [new] paper reminds us that maintenance of adequate serum 25-OH D levels in our elderly population is clinically important and that, based on existing evidence, vitamin D supplementation should be targeted to reach levels (i.e. 20-29 ng/ml) that are safe as well as efficacious," they added.

Science supports maintaining adequate levels of vitamin D, with deficiency in adults reported to precipitate or exacerbate osteopenia, osteoporosis, muscle weakness, fractures, autoimmune diseases, infectious diseases and cardiovascular diseases.

The new study, led by the University of Minnesota’s Kristine Ensrud, MD, supports the need for adequate levels. Over 4,500 women participated in the study, none of whom were considered frail at the start of the study. The researchers report that women with lower vitamin D levels at the start of the study were associated with an increased risk of frailty or death after 4.5 years of study.

"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 said.

Journal of Clinical Endocrinology & Metabolism 95(12):5266-5273, 2010

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