Heart attack: fish and seeds rich in omega-3 reduce the risk of death by 10%

Following a diet rich in omega 3 from plant and marine sources can reduce the risk of death from a heart attack. High blood concentrations of alpha-linolenic acid found in certain seeds, such as flaxseed or chia, and of EPA, DHA, and DPA abundant in fish oil, are associated with a 10% lower risk of fatal cardiac events.

This is the result of research published in JAMA Internal Medicine and conducted by researchers from several prestigious centers including the University School of Medicine at Stanford and Tufts University in Boston (USA).

Omega-3 of plant and marine origin

Alpha-linolenic acid (ALA) is an essential omega-3 fatty acid, meaning it must be consumed through the diet because the body cannot produce it. ALA is the precursor from which the more well-known omega-3 fatty acids originate: EPA and DHA, which are found in high concentrations in oils of cold-water fish such as salmon, cod, mackerel, tuna, etc. The ALA content in fish products is quite low (generally less than 1%), while it is found in appreciable amounts in some plant-based foods including chia seeds, flaxseeds and flaxseed oil, cranberry seeds, walnuts, walnut oil, and soybean oil. Although these foods are excellent sources of ALA, they are poor in its derivatives EPA and DHA. ALA has several beneficial functions for the body: it acts as an anti-aggregant, vasoprotective, and antithrombotic agent; in particular, it reduces platelet viscosity by altering their aggregating potential, thus counteracting the formation of atherosclerotic plaques, and also protects blood vessels from damage. Thanks to these actions, it contributes to reducing cardiovascular risk, along with omega-3 EPA and DHA, which are well known for their benefits on heart health such as reducing the risk of arrhythmias and mortality in patients with recent myocardial infarction or heart failure. Despite knowledge about the actions of plant-derived omega-3, most studies on cardioprotective activity of polyunsaturated fatty acids have been conducted on EPA and DHA.

Plant-based omega-3 also protect the heart

The study conducted by American researchers is a meta-analysis, meaning it compared the results of dozens of other studies on plant and marine omega-3 and cardiac events. Results showed that subjects with the highest blood omega-3 levels had a 25% lower risk of dying from a heart attack compared to those with the lowest levels. Overall, omega-3 from both plant sources and fish products were associated with a 10% lower risk of fatal cardiac events, while no link was found between high omega-3 levels from fish and non-fatal heart attacks. Specifically, results showed that ALA was associated with a 9% lower risk of fatal heart attack, while DPA and DHA were linked to a 10% lower risk. DPA was also related to a 6% lower risk of heart attack overall. According to Liana Del Gobbo, the research fellow who conducted the study, this suggests a mechanism by which omega-3 specifically reduce the risk of death. These new findings, along with those of other recent studies, provide a more complete and updated picture of how omega-3 can influence heart disease. Two other authors of the research, Dariush Mozaffarian and Victoria Taylor, emphasized how the study confirms the importance of consuming fatty fish as part of a healthy and balanced diet to protect heart health, and suggests a positive role for omega-3 from plant sources such as flaxseed, canola, and soybean oils. The study’s results came just days after another meta-analysis published in Clinical Nutrition showed that patients undergoing cardiac surgery who consumed omega-3 supplements before the operation had reduced postoperative arrhythmia and a hospital stay shorter by 2.4 days compared to those who received placebo.

Some details of the meta-analysis

The study included data from 45,637 participants from 16 different countries. For each, researchers collected information on blood concentrations of molecules derived from omega-3 in fish: DHA, EPA, DPA (docosapentaenoic acid), and those derived from ALA. Concentrations of other blood lipids such as phospholipids and cholesterol esters, as well as the amount of adipose tissue, were also measured and related to the presence of coronary disease. According to Dr. Mozaffarian, measuring omega-3 blood levels is important because most previous research estimated omega-3 intake from dietary questionnaires, a less accurate method prone to error.

An innovative study needing further exploration

According to the researchers who led the meta-analysis, concentrations of molecules derived from marine and plant omega-3 are associated with a lower incidence of fatal coronary disease, and this new approach offers an unprecedented opportunity to understand how molecules measured in the blood from omega-3 of different origins can influence health. Although the new research provides further evidence on omega-3 benefits, more analyses of this type are needed, especially focusing on consumer education and awareness. Recently it has been shown that most of the world population consumes too little omega-3 to enjoy any cardiovascular benefit. Few people follow healthy eating recommendations to eat at least one portion of oily fish per week. Statistics have shown that in some parts of the world only one-third of this amount is consumed. On this topic, Harry Rice, vice-president of the Global Organization for EPA and DHA (GOED), commented on the publication reminding that all omega-3 are necessary for health, but reductions in cardiovascular risk are greater when EPA and DHA reach levels comparable to those observed in the Japanese population, and that in Western populations ALA consumption is almost always adequate while EPA and DHA intake is still far from optimal.

Source: Del 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 Internal Medicine.