Marine n-3 (omega-3) fatty acids do not prevent cancer or cardiovascular disease events (VITAL)

Référence

Manson JE, Cook NR, Lee IM, et al, for the VITAL Research Group. Marine n-3 fatty acids and prevention of cardiovascular disease and cancer. N Engl J Med 2019;380(1):23-32.

Sommaire

A recent POEM reported that a UK trial of n-3 fatty acids in 15,000 patients with diabetes found no evidence of benefit as primary prevention. The current study is the first adequately powered US trial of n-3 (omega-3) fatty acids for primary prevention. The researchers recruited a total of 25,781 men 50 years and older and women 55 years and older who had no history of cardiovascular disease or cancer. The groups were balanced at the start of the study, with a mean age of 67 years, 51% women, and 14% with diabetes. The investigators used a 3-month placebo run-in period to exclude patients who were noncompliant, which was approximately one-third of those initially recruited. This could overestimate the potential benefit seen in clinical practice. In this arm of the trial, participants were randomly assigned to 1 g n-3 fatty acids or placebo once daily. The median follow-up was 5.3 years. There was no reduction in the likelihood of cancer diagnosis or of the primary composite cardiovascular outcome (cardiovascular death, nonfatal myocardial infarction [MI], or ischemic stroke). There was no difference between groups regarding cardiovascular or all-cause mortality. There was a reduction in total MIs (hazard ratio 0.72; 95% CI 0.59 - 0.90), although the absolute reduction was small (145 vs 200 total MIs with >12,000 patients in each group). It is important not to make too much of this finding, as there were 24 comparisons made in the primary analysis, so this one could be caused by chance alone. There was no difference between groups with regard to adverse events. A subgroup analysis found a modest but statistically significant reduction in the primary composite outcome for persons who ate fewer than 1.5 servings of fish per week, but not in those who ate more.