Vitamin D and multiple health outcomes: umbrella review of systematic reviews and meta-analyses of observational studies and randomised trials.

23 We specifically identified outcomes for which meta-analyses of observational studies showed nominally significant associations (at P≤0.05), did not have large between study heterogeneity, were based on evidence from more than 500 cases (or more than 5000 total participants if the type of metric was continuous), and showed no evidence of small study effects or excess significance.

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On the basis of the results of this umbrella review (table 6), highly convincing evidence of a clear role of vitamin D with highly significant results in both randomised and observational evidence does not exist for any outcome.

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