RCT2019 · NEJM · Manson JE et al.
VITAL: vitamin D and omega-3 — no blanket protection, but subgroups benefit
Who, how long
25,871 US adults over 50/55, 5.3 years
What they found
2,000 IU D3 and 1 g fish oil did not reduce overall cancer or cardiovascular events; fish oil gave –19% events in low fish eaters, D3 signalled –17% cancer mortality and –22% autoimmune disease.
⚠ Caveat
Most participants weren't vitamin D deficient — the trial doesn't answer for deficient people.
Related in the knowledge base
Last reviewed: 6 September 2026
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