• 25,871 healthy participants received either a daily 1g capsule of omega-3 fatty acids (840 mg of EPA+DHA) or a placebo.
  • This is the first study of the effects of long-chain omega-3s on cardiovascular risk ever conducted on a healthy population, and it provides the first insights on the effect of these nutrients in a low-risk population.
  • VITAL found that treatment reduced the risk of major coronary heart disease (CVD) events by about 8%, but this was not statistically significant. It also found that the risk of MI (myocardial infarction/heart attack) was reduced by 28%, which did reach statistical significance.

Note: Even though the results of VITAL were more positive than expected, there was a mixture of positive and negative media coverage, leaving some understandably confused. The negative headlines have been focusing on the fact that the study did not significantly reduce major CVD events (with only an 8% reduction), however the 28% reduction of MI was shown to be significant, which is what the positive coverage has been focusing on.


The VITamin D and OmegA-3 TriaL (VITAL) is an ongoing randomized clinical trial of vitamin D (in the form of vitamin D3 [cholecalciferol]) and marine omega-3 fatty acid (eicosapentaenoic acid [EPA] + docosahexaenoic acid [DHA]) supplements in the primary prevention of cancer and cardiovascular disease (CVD). Existing data from laboratory studies, epidemiologic research, small primary prevention trials, and/or large secondary prevention trials strongly suggest that these nutritional agents may reduce risk for cancer or CVD, but large primary prevention trials with adequate dosing in general populations are lacking.

VITAL will test the independent effects of vitamin D and omega-3 fatty acid supplementation on risk for developing cancer and CVD (primary, secondary, and other outcomes are specified in the Outcome Measures section). VITAL will also explore (a) whether vitamin D and omega-3 fatty acid supplements exhibit synergistic or additive effects on cancer and CVD risk and (b) whether the effect of each supplement on cancer and CVD risk varies by baseline blood levels of vitamin D and EPA+DHA, race/ethnicity (for vitamin D), and body mass index (for vitamin D), as well as age, sex, sunlight exposure, calcium and phosphorus intakes, and baseline risk factors for cancer and CVD.

Eligible participants were assigned by chance (like a coin toss) to one of four groups: (1) daily vitamin D and omega-3; (2) daily vitamin D and omega-3 placebo; (3) daily vitamin D placebo and omega-3; or (4) daily vitamin D placebo and omega-3 placebo. Participants had an equal chance of being assigned to any of these four groups and a 3 out of 4 chance of getting at least one active agent.

Participants in all groups take two pills each day — one softgel that contains either vitamin D or vitamin D placebo and one capsule that contains either omega-3 or omega-3 placebo. Participants receive their study pills in convenient calendar packages via U.S. mail.

Participants also fill out a short (15-20 minute) questionnaire each year. The questionnaire asks about health; lifestyle habits such as physical exercise, diet, and smoking; use of medications and dietary supplements; family history of illness, and new medical diagnoses. Occasionally, participants may receive a phone call from study staff to collect information or to clarify responses on the questionnaire.

At baseline, 16,954 VITAL participants provided an optional blood sample. Approximately 6,000 of these participants provided a follow-up blood sample during years 1-4 of the trial.

At baseline, year 2, and year 4 of the trial, a subcohort of 1,054 VITAL participants living within driving distance of Boston, Massachusetts received detailed in-clinic health assessments at the Clinical and Translational Science Center (CTSC) of Brigham and Women’s Hospital. During CTSC visits, participants have a clinical exam, including measurement of height, weight, other anthropometrics, blood pressure, and physical performance. They also provide fasting blood and urine samples, and undergo 2-hour oral glucose tolerance testing, lung function testing (spirometry), electrocardiograms, bone mineral density testing, 2D-echocardiography, and assessments of thinking and mood.