Omega-3s, found in Walnuts and Some Fish, May Lower the Risk of Fatal Heart Attacks

New research published in JAMA Internal Medicine found that blood biomarkers of plant and seafood-based omega-3s are associated with a modestly lower risk (up to 10 percent) of dying from heart attacks1. Researchers conducted a meta-analysis of 19 studies to better understand how consumption of plant and seafood-based omega-3s are associated with risk of death from a heart attack, coronary heart disease (CHD), and sudden cardiac death. The 19 studies represented more than 45,000 individuals from 16 countries and looked at biomarkers of omega-3s, which, according to the researchers, are a more reliable way to measure the amount of omega-3s consumed than questionnaires that ask about eating habits. The median age of participants was 59 years, but the ages ranged from 18-97 years, with approximately 63% of the participants being male. 

Walnuts are the only nut to contain an excellent source of plant-based omega-3s (alpha-linolenic acid or ALA), offering 2.5 grams of ALA per ounce (approximately one-quarter cup). According to the American Heart Association, there is a death from heart disease every 84 seconds in the United States. The results of this globally-represented paper highlight the importance of food choices not only on overall wellness, but also on specific illnesses such as heart disease.

As with any research, limitations should be considered. Since this was an observational study, residual confounding cannot be ruled out (i.e., other lifestyle habits that are common in adults who eat foods with omega-3s could contribute to the study findings) and direct cause and effect cannot be established. It is also possible that subjects may have misreported their dietary intake since this information was collected by questionnaires. Some biomarkers were not largely represented in the studies, which limited the references for these specific components. Relatively few studies were available for some lipid compartments (e.g., adipose, cholesterol esters), limiting inference for these specific compartments. All cohorts assessed omega-3 polyunsaturated fatty acid exposure once at baseline, and changes over time would attenuate findings toward the null, causing underestimation of associations. Reduced statistical power in quintile analyses and spline analyses made it difficult to ascertain the specific shape of dose responses.

1Del Gobbo LC, Imamura F, Aslibekyan S, et al. ω-3 Polyunsaturated Fatty Acid Biomarkers and Coronary Heart Disease: Pooling Project of 19 Cohort Studies. JAMA Intern Med. 2016;176(8):1155-1166. doi:10.1001/jamainternmed.2016.2925.