Vitamin D and risk of cause specific death: systematic review and meta-analysis of observational cohort and randomised intervention studies

Study answer

What this study found

Overall vitamin D supplementation did not significantly reduce all-cause mortality across all trials, with a pooled risk ratio of 0.98 (0.94 to 1.02). In subgroup analyses, vitamin D3 was associated with lower all-cause mortality, RR 0.89 (0.80 to 0.99), whereas vitamin D2 showed no benefit, RR 1.04 (0.97 to 1.11). The intervention arm recorded 2527 all-cause deaths versus 2587 in control across the pooled trials. The review concluded that vitamin D3 may reduce mortality in older adults, but the overall evidence does not support a clear mortality benefit for vitamin D supplementation as a…

Study & population

Systematic review and meta-analysis of observational cohort studies and randomized intervention trials assessing mortality outcomes related to circulating 25-hydroxyvitamin D and vitamin D supplementation.

Intervention

In the randomized trials, vitamin D was given orally as tablets, mainly as daily vitamin D3 (cholecalciferol) at 10 to 6000 IU/day or daily vitamin D2 (ergocalciferol) at 208 to 4500 IU/day.

Key limitation

The randomized evidence was heterogeneous in vitamin D form, dose, duration, and trial quality, which limits direct comparison and makes the pooled estimate less definitive.

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Original abstract