Is Vitamin D good for bone health?

The evidence points that way, though it's not yet conclusive. A large meta-analysis in the BMJ and an earlier meta-analysis both found vitamin D supplementation modestly reduces all-cause mortality, though effects are inconsistent across trial populations. That's reflected in an evidence score of 51/100 for its role in bone health, drawn from 11 studies, with an estimated impact on longevity rated moderate (36/100).