For years it’s been claimed and widely accepted that taking ‘omega-3’ fish oil supplements can help protect you against heart disease, strokes or early death from cardiovascular events.
At one time they were even prescribed on the NHS to people who had suffered a heart attack. But new research challenges that belief, claiming there is little or no evidence that such supplements do any good.
It comes from Cochrane, an internationally-recognised organisation dedicated to providing accurate and up-to-date evidence to support decision making on healthcare policy. It has just published a systematic review of results from 79 trials involving more than 112,000 people in Europe, North America, Australia and Asia. Most of these trials investigated the impact on health outcomes of giving omega-3 supplements in capsule form compared to a placebo (a dummy pill).
Omega-3 is a type of fat. Small amounts of omega-3 fats are essential for good health and can be found in the food we eat. The main types of omega-3 fatty acids are alphalinolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA). ALA is normally found in fats from plant foods, such as nuts and seeds (walnuts and rapeseed are rich sources). EPA and DHA, collectively called ‘long chain omega-3 fats’, are naturally found in fatty fish, such as salmon, fresh tuna and mackerel, and fish oils, including cod liver oil.
Increased consumption of omega-3 fats is widely promoted globally because of a common belief that that it will protect against heart disease, for example, by reducing blood pressure or cholesterol. But having systematically reviewed results from 79 studies, the Cochrane researchers found that:
- Increasing intake of long chain omega-3 fats had little or no meaningful effect on the risk of death from any cause.
- The risk of death from any cause was 8.8% in people who had increased their intake of omega-3 fats, compared with 9% in people who hadn’t.
- Taking more long chain omega-3 fats primarily through supplements probably makes little or no difference to risk of cardiovascular events, coronary heart deaths, coronary heart disease events, stroke or heart irregularities.
- Only one in a thousand people might benefit from a reduced risk of cardiovascular events or cardiovascular death through increased consumption of ALA in omega-3 supplements.
Cochrane lead author Dr Lee Hooper, from the University of East Anglia, said: “We can be confident in the findings of this review, which go against the popular belief that long chain omega-3 supplements protect the heart. This large systematic review included information from many thousands of people over long periods. Despite all this information, we don’t see protective effects.
“The review provides good evidence that taking long chain omega-3 supplements does not benefit heart health or reduce our risk of stroke or death from any cause. On the other hand, while oily fish is a healthy food, it is unclear from the small number of trials whether eating more oily fish is protective of our hearts.
“This systematic review did find moderate evidence that ALA, found in plant oils (such as rapeseed or canola oil) and nuts (particularly walnuts) may be slightly protective of some diseases of the heart and circulation. However, the effect is very small.”
Despite casting doubt on the effectiveness of omega-3 supplements, the researchers stress that eating foods high in Omega-3 fats, such as oily fish, nuts and seeds can still be recommended as part of a healthy balanced diet which is good for general health.