Cardiovascular disease is an umbrella term that encompasses coronary artery disease, heart attack, stroke, hypertension, and other conditions. Together, they are the primary cause of death worldwide, claiming the lives of nearly 18 million people every year. Findings from a recent meta-analysis suggest that omega-3 fatty acids reduce the risk of developing cardiovascular disease.

Omega-3 fatty acids are essential nutrients that play critical roles in cardiovascular function, due to their participation in pathways involved in blood clotting, inflammation, and the contraction and relaxation of arteries. Omega-3s with the greatest relevance for humans include alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). ALA is found mainly in plant oils such as flaxseed, soybean, and canola oils. EPA and DHA are found in the meat and oils of fatty cold-water fishes and seafood. The human body can convert some dietary ALA into EPA and then to DHA, but the process is inefficient.

The findings from studies investigating the health effects of omega-3s have been inconsistent, likely due to differences in study design, many of which rely on data from food frequency questionnaires, which are subject to recall bias, and nutrient databases, which can be inaccurate. Measuring omega-3 blood levels provides a more accurate assessment of exposure.

The authors of the meta-analysis reviewed data from 17 studies that investigated links between blood levels of omega-3s and the risk for all causes of premature death. The studies included more than 42,000 adults (average age, 65 years) living in 10 countries. The authors classified the participants according to five categories of omega-3 intake, ranging from high to low.

They found that participants with the highest blood levels of EPA and DHA combined were 18 percent less likely to die from all causes of premature death, compared to those with the lowest levels. When they analyzed death rates by specific causes, they found that those with the highest blood levels of EPA and DHA combined were 20 percent less likely to die from cardiovascular disease and 13 percent less likely to die from cancer.

These findings suggest that omega-3s reduce the risk of premature death from all causes and from cardiovascular disease. The authors noted that their findings did not establish causality and may in fact be indicators of healthy lifestyles among the participants. Further study is warranted.

• Link to full study.