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Low vitamin D levels linked with increased risk of death

Individuals with low levels of vitamin D appear to have a higher risk of death from all causes, according to a report in the August issue of Archives of Internal Medicine.

Several studies have suggested that vitamin D deficiency contributes to cardiovascular disease, cancer and death, according to background information in the article. The optimum blood level of 25-hydroxyvitamin D has been suggested to be 30 nanograms per milliliter or higher.

The researchers analysed vitamin D levels in 13,331 individuals. Over a median (midpoint) of 8.7 years of follow-up, 1,806 of the participants died. When they were divided into four groups based on their vitamin D levels, those in the group with the lowest level (less than 17.8 nanograms per milliliter) had a 26% increased rate of death from any cause compared with those in the group with the highest vitamin D levels. No significant associations were found when the researchers assessed vitamin D levels and risk of death from cardiovascular disease or cancer alone.

Low vitamin D levels may be associated with death through their effect on blood pressure, the body's ability to respond to insulin, obesity and diabetes risk, the authors note. Several lines of evidence support vitamin D's role in death risk, including the fact that cardiovascular events are more common in the winter, when vitamin D levels are lower, and that cancer survival is better if the disease is diagnosed in the summer when levels are higher.

Archives of Internal Medicine