Vitamin D and the endocrinology of ageing

Vitamin D is an important prohormone largely derived from sunlight exposure on the skin. In many older people, vitamin D levels have been found to be insufficient or frankly deficient. Alterations in body composition associated with ageing, such as decreased muscle mass and increased adipose tissue, may also decrease vitamin D levels. Low vitamin D levels are associated with an increased risk of falls and fractures and the conditions of frailty and sarcopenia, but confounding with decreased outdoor exposure from a large range of concomitant diseases partly explains these findings. The benefits of vitamin D supplementation found in randomised trials have largely been confined to frail and disabled older people. There is some evidence that bolus vitamin D supplements that achieve supraphysiological levels may increase the risk of falls.