A new meta-analysis1 sponsored by the Global Organization for EPA and EHA Omega-3s (GOED; Salt Lake City) appears to offer some of the most compelling data yet linking omega-3 consumption with a reduced risk of coronary heart disease (CHD). The study, published in Mayo Clinic Proceedings earlier this week, is “the most comprehensive meta-analysis to date on CHD and omega-3s,” according to GOED.
The meta-analysis included 18 randomized controlled trials (RCTs) and 16 prospective cohort studies, with total study populations of 93,000 and 732,000, respectively. Studies were found through a systematic literature search covering the period from January 1, 1947 to November 2, 2015.
Researchers found that consumption of EPA and DHA from supplements and/or foods resulted in statistically significant reductions to CHD risk in high-risk populations, including participants with high triglycerides (16% reduction in CHD risk) and participants with high LDL cholesterol (14% reduction in CHD risk). Across all populations, there was a non-statistically significant 6% reduction of CHD risk in the RCTs, and a significant 18% reduction of CHD risk in the prospective cohort studies.
“There are important public health implications related to reducing the risk of coronary heart disease, and therefore we are encouraged by the results of this comprehensive analysis,” said Harry Rice, PhD, vice president of regulatory and scientific affairs for GOED, in the study announcement. “It’s also important that the observed risk reductions were even stronger in patient populations with elevated triglycerides and LDL cholesterol levels, two risk factors that affect more than one quarter of the American population.”
GOED also noted that the observed differences in CHD risk reduction between the RCTs and the prospective cohort studies (6% versus 18%) may be due to the fact that prospective cohort studies generally track larger populations across longer periods of time.
“What makes this paper unique is that it looked at the effects of EPA and DHA on coronary heart disease specifically, which is an important nuance considering coronary heart disease accounts for half of all cardiovascular deaths in the U.S.,” said Dominik Alexander, PhD, lead author of the study. “The 6% reduced risk among RCTs, coupled with an 18% risk reduction in prospective cohort studies—which tend to include more real-life dietary scenarios over longer periods—tell a compelling story about the importance of EPA and DHA omega-3s for cardiovascular health.”
Omega-3s During Pregnancy to Reduce Asthma Risk
Just before the publication of the aforementioned meta-analysis, another positive study2 on omega-3 supplementation was released. This study, published in The New England Journal of Medicine, found that pregnant women who took omega-3s during their third trimester of pregnancy had offspring with reduced levels of asthma.
The study included 736 pregnant women who were randomized to consume 2.4 g of omega-3 fish oil or a placebo every day from 24 weeks after gestation until the end of their pregnancy. Researchers then followed up with 695 of the children for the first five years of their lives for incidence of persistent wheeze or asthma, as well as lower respiratory tract infections, asthma exacerbations, eczema, and allergic sensitization.
Researchers found that the treatment group offspring presented with a 16.9% risk of persistent wheeze or asthma, compared to a 23.7% risk in the control group—a difference of nearly 7%, or a relative reduction of 30.7%. The reduction in asthma risk was especially pronounced in offspring of mothers in the lowest third for EPA and DHA blood levels at baseline—a 17.5% risk for the treatment group compared to a 34.1% risk for the control group.
Meanwhile, the treatment group also had a reduced risk of infections of the lower respiratory tract, but there were no statistically signification associations for the other measured end points.
“Supplementation with [omega-3s] in the third trimester of pregnancy reduced the absolute risk of persistent wheeze or asthma and infections of the lower respiratory tract in offspring by approximately 7 percentage points, or one third,” researchers concluded.
Nutritional Outlook Magazine
1. Alexander D et al., “A meta-analysis of randomized controlled trials and prospective cohort studies of eicosapentaenoic and docosahexaenoic long-chain omega-3 fatty acids and coronary heart disease risk,” Mayo Clinic Proceedings, vol. 92, no. 1 (January 2017): 15–29
2. Bisgaard H et al., “Fish oil-derived fatty acids in pregnancy and wheeze and asthma in offspring,” The New England Journal of Medicine, vol. 375, no. 26 (December 2016): 2530—2539