“Vitamin D supplementation reduces mortality”

## The VITAL Trial Evidence VITAL (Manson et al., *NEJM*, 2019) randomised 25,871 US adults to 2,000 IU/day vitamin D3 plus 1g omega-3 or placebo. After 5.3 years, there was no significant reduction in all-cause mortality, cardiovascular disease, or total cancer incidence in the primary analysis. A post-hoc finding suggested a 17% reduction in cancer mortality after 2+ years — potentially meaningful but requires replication. ## Who Does Benefit People with vitamin D deficiency (levels <20 ng/mL) clearly benefit from supplementation — their elevated mortality and disease risk drops toward normal with treatment. The question is whether *supplementing already-sufficient* people extends benefits further. Current evidence says no. ## Practical Guidance Test your 25-OH-D level. If deficient, supplement to reach 40–60 ng/mL. If already sufficient, spending money on high-dose vitamin D has limited evidence of benefit. Sunlight exposure (with appropriate UV index) remains the most physiological source.