An updated meta-analysis centered around the role marine omega-3 supplementation in CVD prevention suggests there may be a use for fish oil in cardiovascular medicine after all.
Conflicting findings from recent randomized controlled trials and observational studies have muddled our perception of the relationship between fish oil supplements and CVD prevention, JoAnn E. Manson, MD, DrPH, and colleagues said in the Journal of the American Heart Association—and that includes one of Manson’s own projects, the VITAL study. VITAL, presented at the American Heart Association’s 2018 Scientific Sessions, tested the utility of marine omega-3 fatty acids and vitamin D3 in preventing CVD and cancer in a cohort of 25,871 Americans.
Though the trial was large-scale, diverse and placebo-controlled, omega-3 supplementation was linked only to a statistically insignificant 8% reduction in the study’s primary endpoint of major CVD events. Manson’s team’s results stood in stark contrast to those of REDUCE-IT, another study presented at the conference that found a 25% reduced risk of major CV events with 4 grams per day of icosapent ethyl, a purified eicosapentaenoic acid product.
In the latest meta-analysis published Sept. 30, Manson, of Harvard Medical School, and her colleagues considered study-level data from 13 trials focused on omega-3 supplementation. Outcomes of interest included MI, coronary heart disease (CHD) death, total CHD, total stroke, CVD death, total CVD and major vascular events; REDUCE-IT data were excluded in a sub-analysis.
Over an average duration of five years, Manson et al. noted 3,838 MIs; 3,008 CHD deaths; 8,435 total CHD events; 2,683 strokes; 5,017 CVD deaths, 15,759 total CVD events and 16,478 major vascular events in the study population. Excluding REDUCE-IT data, marine omega-3 supplementation was linked to an 8% reduced risk of MI, 8% reduced risk of CHD death, 5% lower risk of CHD death, 7% lower risk of CVD death and 3% lower risk of total CVD.
Results from the analysis seemed to suggest daily marine omega-3 supplementation can be effective in lowering people’s risk of CVD, but they didn’t seem to have any benefit for stroke prevention. Greater cardiovascular benefits might be achieved at higher doses of omega-3s, Manson and co-authors said.
“In the current study, the linear dose-response relationship observed between marine omega-3 supplementation and several CVD endpoints is both clinically and biologically plausible,” the team wrote. “Because most included trials comprise patients at high risk of CVD and with advanced atherosclerosis, a high dose of marine omega-3 supplementation may be needed to achieve potential benefits in this setting.
“Nevertheless, our dose-response analysis was highly exploratory and should be interpreted cautiously.”
Large-scale trials that focus more exclusively on higher doses of marine omega-3s are warranted to confirm the findings of the present analysis, Manson and colleagues said, and to extend our current knowledge base.