New health evidence challenges the belief that omega-3 supplements reduce the risk of heart disease, stroke, or death


New evidence released today shows that omega-3 supplements have little or no effect on our risk of suffering heart disease, stroke, or death.

Omega 3 is a type of fat. Small amounts of omega-3 fats are essential to good health and can be found in the food we eat. The main types of omega-3 fatty acids are; Alpha linolenic acid (ALA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). ALA is usually found in fats from plant foods such as nuts and seeds (walnuts and canola are rich sources). EPA and DHA, collectively known as long-chain omega-3 fats, are found naturally in oily fish such as salmon and fish oils including cod liver oil.

Increased consumption of omega-3 fats is widely promoted around the world as it is widely believed that they protect against heart disease. There is more than one possible mechanism by how they can help prevent heart disease, including lowering blood pressure or lowering cholesterol. Omega-3 fats are readily available as over-the-counter dietary supplements and are widely purchased and used.

A new systematic review by Cochrane, published today in the Cochrane Library, combines the results of seventy-nine randomized trials involving 112,059 people. These studies looked at the effects of consuming extra omega-3 fat compared to normal or lower omega-3 fat on cardiovascular disease. 25 studies were rated as very trustworthy because they were well designed and conducted.

The studies recruited men and women, some healthy and others with existing diseases, from North America, Europe, Australia and Asia. Participants were randomly assigned to increase their omega-3 fats or maintain their usual fat intake for at least a year. Most studies looked at the effects of a long-chain omega-3 supplement in capsule form and compared it to a dummy pill. Few rated whole fish intake. Most ALA studies added omega-3 fats to foods such as margarine and gave those fortified foods or naturally ALA-rich foods such as walnuts and other participants normal (non fortified) foods to intervention group participants.

The Cochrane researchers found that increasing long-chain omega-3s had little, if any, benefit in most of the results they studied. They found evidence with a high degree of certainty that long-chain omega-3 fats have little or no significant influence on the risk of death, regardless of the cause. The risk of death from any cause was 8.8% for those who had increased their omega-3 fat intake compared to 9% for those in the control groups.

They also found that ingesting more long-chain omega-3 fats (including EPA and DHA), primarily through dietary supplements, likely had little or no effect on the risk of cardiovascular events, coronary death, coronary artery disease, stroke, or heart irregularities . Long chain omega-3s have likely reduced some blood lipids, triglycerides, and HDL cholesterol. Reducing triglycerides will likely protect against heart disease, but reducing HDL has the opposite effect. The researchers gathered information about damage from the studies, but information about bleeding and blood clots was very limited.

The systematic review suggests that consuming more ALA through food or supplements is likely to have little or no effect on cardiovascular death or death from any cause. However, taking more ALA is likely to reduce the risk of heart irregularities from 3.3% to 2.6%. The review team found that the reduction in cardiovascular events with ALA was so small that about 1,000 people would have to increase their use of ALA for either of them to benefit. Similar results were found for cardiovascular death. They did not find enough data from the studies to measure the risk of bleeding or blood clots from using ALA.

Increasing long-chain omega 3 or ALA is unlikely to have any effect on body weight or fat.

Cochrane lead author Dr. Lee Hooper of the University of East Anglia, UK, said, “We can rely on the results of this review, which contradict the popular belief that long chain omega-3 supplements are heart protective. This large systematic review contained information from many thousands of people over long periods of time. Despite all this information, we do not see any protective effects.

“The review provides good evidence that taking long-chain omega-3 supplements (fish oil, EPA, or DHA) does not benefit heart health or reduce our risk of stroke or death from any cause. The most trusted studies consistently showed little or no effect of long-chain omega-3 fats on cardiovascular health. On the other hand, while oily fish is a healthy food, the small number of studies unclear whether consuming more oily fish affects our hearts protects.

“This systematic review found moderate evidence that ALA, found in vegetable oils (such as canola or canola oil) and nuts (especially walnuts), can easily protect some heart and circulatory diseases. However, the effect is very little. 143 people would need to increase their ALA intake to prevent one person from developing arrhythmias, a thousand people would need to increase their ALA intake to prevent one person from dying from coronary artery disease or having a cardiovascular event. ALA is an essential fatty acid, an important part of a balanced diet, and increased intake can be slightly beneficial in the prevention or treatment of cardiovascular disease. “