Omega 3 fatty acids for prevention and treatment of cardiovascular disease.

Systematic review of randomized controlled trials and cohort studies in adults aged 18 years and older at varying cardiovascular risk, including people with established cardiovascular disease. The review included both dietary advice and supplemental omega-3 interventions, and excluded pregnant and acutely ill individuals.

The intervention was omega-3 fatty acid exposure delivered in multiple ways across studies, including fish oil capsules, concentrated EPA plus DHA capsules, alpha-linolenic acid from linseed oil, and dietary fish advice. Doses and duration varied widely, ranging from 0.5 g EPA/day or 0.9 g EPA plus DHA/day to higher capsule regimens such as 3.3 g/day, 5.4 g/day, or 7.0 g/day of omega-3-related fatty acids, as well as 2 weekly portions of fatty fish in dietary arms.

Overall, there was no clear evidence that dietary or supplemental omega-3 fats altered total mortality, combined cardiovascular events, or cancers in people with, or at high risk of, cardiovascular disease or in the general population. The authors concluded that there is no evidence to advise people to stop taking rich sources of omega-3 fats, but further high quality trials are needed to confirm any protective cardiovascular effect. No clear differences in effectiveness were seen by fish versus plant source, dietary versus supplemental source, dose, or presence of placebo.

The evidence base was heterogeneous, combining different populations, study designs, omega-3 sources, doses, and comparators, which makes pooled interpretation difficult. Many interventions were small or short term, and the review’s overall conclusions depend on trials with variable outcome definitions and incomplete consistency across endpoints.