Men's Osteoporosis Support GroupVitamin D and mortality in older men Am J Clin Nutr. 2010 Oct;92(4):841-8. Epub 2010 Aug 18. Plasma vitamin D and mortality in older men: a community-based prospective cohort study. Michaëlsson K and others. PMID: 20720256. This is a 12-year longitudinal study of 1,194 older men (71 or older) to see how serum vitamin D levels correlate with mortality. The results showed a U-shaped association between vitamin D concentrations and total mortality. That is, low levels and high levels were associated with greater mortality, but not normal levels. The lowest 10% and the highest 5% of vitamin D concentrations showed about a 50% higher total mortality rate. Additionally, cancer mortality was higher at both low and high concentrations, while cardiovascular death was greater at only low vitamin D levels. The authors conclude, "Both high and low concentrations of plasma 25(OH)D are associated with elevated risks of overall and cancer mortality. Low concentrations are associated with cardiovascular mortality." Editor's comments. Vitamin D is an important vitamin/hormone regarding osteoporosis and bone mineralization, so it is prescribed to virtually everyone who begins treatment for osteoporosis. This study, and others I've seen, including a recent Update on pancreatic cancer risk and serum vitamin D levels, suggest that we should be careful not to assume that if a little vitamin D is good, a lot would be even better. A recent study in the J Natl Cancer Inst, Volume100, Issue11, Pp. 796-804, by Ahn J and others, concluded, "The findings of this large prospective study do not support the hypothesis that vitamin D is associated with decreased risk of prostate cancer; indeed, higher circulating 25(OH)D concentrations may be associated with increased risk of aggressive disease." Note there is some precedence for the U-shaped response to serum vitamin levels as demonstrated in this Update on excess vitamin A and fracture risk. Both high and low levels were correlated with increased fracture risk. So this is three recent studies that cast some doubt on the idea of mega-dosing vitamin D to gain super high serum levels. That would be either with supplements or increased solar UVB radiation, presumably. Until further studies can cast more light on this issue, it appears to be wise to maintain recommended serum vitamin D levels of around 30 ng/mL or 75 nmol/L. Discuss this issue with your care provider, and I suggest you have your serum vitamin D levels tested at least yearly to verify that you are in the proper range: neither too high nor too low.
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