Levels of Vitamin D and women

Both low and high levels of vitamin D are associated with higher risk of frailty in older women.

Vitamin D deficiency and frailty (including weakness and slowness) are common with ageing. Many experts recommend monitoring vitamin D levels in older adults and prescribing vitamin D supplementation if levels are less than 30 ng/ml. Despite the popularity of Vitamin D supplementation, the association between vitamin D status and risk of adverse health outcomes in older adults is uncertain.

To study this, researchers in America measured vitamin D levels and assessed frailty in 6307 women aged 69 years and older. To determine whether lower vitamin D levels were associated with an increased risk of greater frailty status at a later date, 4,551 women classified as non-frail at baseline had frailty status reassessed an average of 4.5 years later.

This new study found a U-shaped relationship between vitamin D levels and frailty; older women with vitamin D levels higher than 30 ng/ml and those with levels lower than 20 ng/ml were more likely to be frail. 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 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.

Further studies 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.

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