VITAL (VITamin D and OmegA-3 TriaL)
The definitive test of whether vitamin D or fish-oil pills prevent cancer or heart disease in healthy adults. They did not.
25,871 participants (including 5,106 Black participants) followed for a median 5.3 years. Vitamin D did not reduce invasive cancer incidence (793 vs 824 events, HR 0.96, 95% CI 0.88-1.06) or major cardiovascular events (HR 0.97); omega-3 did not reduce cancer (HR 1.03) or major cardiovascular events (HR 0.92), though it reduced myocardial infarction in secondary analysis. Total cancer mortality with vitamin D was HR 0.83 (0.67-1.02) overall and HR 0.75 (0.59-0.96) after excluding the first two years, a pre-specified but secondary analysis. Later ancillary analyses reported fewer advanced (metastatic or fatal) cancers with vitamin D, concentrated in normal-weight participants. The trial ended the hope of broad cancer prevention with supplements while leaving a testable mortality hypothesis.
- Vitamin D3: 793 events; Placebo: 824 events.
- These are counts of events, not percentages, so compare them with the group sizes in mind.
- Put another way, the treated group had about 4 percent lower chance of the event at any given time (hazard ratio 0.96, likely range 0.88 to 1.06).
- Omega-3: 820 events; Placebo: 797 events.
- These are counts of events, not percentages, so compare them with the group sizes in mind.
- Put another way, the treated group had about 3 percent higher chance of the event at any given time (hazard ratio 1.03, likely range 0.93 to 1.13).
- The likely range for the hazard ratio crosses 1, so the difference could be due to chance.
- This endpoint is not one of the standard survival or response measures; read it alongside the trial's primary result.
- These results apply to the people the trial enrolled: Primary prevention in US adults (men 50+, women 55+) without prior cancer or cardiovascular disease: vitamin D3 2000 IU/day and/or marine omega-3 1 g/day vs placebo, 2x2 factorial. People in a different situation may not see the same effect.
Numbers are from the trial as recorded here; see the source links in the table below. This is orientation, not medical advice: ask your team how closely the trial population matches you.
25,871 participants enrolled.
| Endpoint | Arm | n | Value | HR (95% CI) | p | Source |
|---|---|---|---|---|---|---|
| Invasive cancer of any typeprimary | Vitamin D3 | 12,927 | 793 events | 0.96 (0.88–1.06) | 0.47 | link |
| Placebo | 12,944 | 824 events | ||||
| Invasive cancer of any typeprimary | Omega-3 | 12,933 | 820 events | 1.03 (0.93–1.13) | — | link |
| Placebo | 12,938 | 797 events |
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