The beneficial effects of vitamin D on bone health are well described. However, vitamin D is also known to influence the renin−angiotensin pathway and cell cycling, and is inversely related to cardiovascular disease, cancer and all-cause mortality. Yet, despite these data, there have been no large population-based trials investigating the impact of vitamin D with mortality as the primary outcome.

Neale and colleagues therefore undertook a randomised, double-blinded, placebo-controlled trial of 21,310 Australian participants aged 60−84 years. Participants were randomised to receive either vitamin D3 (60,000IU per month for 5 years), or placebo.

Vitamin D supplementation was not associated with reduced cancer, cardiovascular disease or all-cause mortality. Whilst there appeared to be an increased hazard of all-cause and cancer mortality at 6 years’ follow-up, the interaction between study group and time was not significant.

This study is strengthened by high adherence and retention (≥80%) and provides caution to earlier reports that vitamin D supplementation might reduce cancer mortality and all-cause mortality. However, it should be noted that the population studied was likely to be vitamin D-replete and monthly high-dose vitamin D3 supplementation was adopted. Thus, the ability to generalise the findings to non-replete populations, using alternate supplementation regimes, remains to be determined.

Read the full article in Lancet Diabetes & Endocrinology 10 120−128