Omega 3 supplementation has “little to no effect” on risk of heart disease, stroke or death: study
18 Jul 2018 --- Debunking the commonly held belief that omega 3 supplementation can protect against heart disease, a new study has found that consuming additional omega 3 fatty acids, compared to usual or lower omega 3, has little to no effect on the risk for cardiovascular events, coronary heart deaths, coronary heart disease events, stroke or heart irregularities.
Increased consumption of omega 3 fats is widely promoted globally because of a common belief that it will protect against heart disease. There is more than one possible mechanism for how they might help prevent heart disease, including reducing blood pressure or reducing cholesterol. Omega 3 fats are readily available as over-the-counter supplements and they are widely bought and used.
The Cochrane systematic review, published in the Cochrane Library, combines the results of seventy-nine randomized trials involving 112,059 people. These studies assessed effects of consuming additional omega 3 fat, compared to usual or lower omega 3, on diseases of the heart and circulation. Twenty-five studies were assessed as highly trustworthy because they were well designed and conducted.
The studies recruited men and women, some healthy and others with existing illnesses from North America, Europe, Australia and Asia. Participants were randomly assigned to increase their omega 3 fats or to maintain their usual intake of fat for at least a year. Most studies investigated the impact of giving a long-chain omega 3 supplements in a capsule form and compared it to a dummy pill. Only a few assessed whole fish intake. Most ALA trials added omega 3 fats to foods such as margarine and gave these enriched foods, or naturally ALA-rich foods such as walnuts, to people in the intervention groups, and usual (non-enriched) foods to other participants.
The Cochrane researchers found that increasing long-chain omega 3 provides little if any benefit on most outcomes that they looked at. They found high certainty evidence that 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 percent in people who had increased their intake of omega 3 fats, compared with 9 percent in people in the control groups.
“If omega 3 supplements are prescribed by a doctor then they should be taken. In others, there is no reason to take omega 3 supplements in order to protect our heart or vascular health. The evidence from our large and comprehensive systematic review is very clear – the 79 trials included over 112,000 participants all randomized for at least a year and up to 8 years. Within the trials over 8,000 people died, over 4500 people died from cardiovascular causes, almost 1,600 people died from coronary causes and over 14,000 people experienced at least one cardiovascular event – there is enormous power here to see any effects that omega 3 may be having on these important outcomes. Despite that we see little or no effect of long-chain omega 3 supplements on any of these outcomes,” Lee Hooper, PhD, Reader in Research Synthesis, Nutrition & Hydration tells NutritionInsight.
They also found that taking more long-chain omega 3 fats (including EPA and DHA), 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. Long-chain omega 3 fats probably did reduce some blood fats, triglycerides and HDL cholesterol. Reducing triglycerides is likely to be protective of heart diseases, but reducing HDL has the opposite effect. The researchers collected information on harms from the studies, but information on bleeding and blood clots was very limited.
The systematic review suggests that eating more ALA through food or supplements probably has little or no effect on cardiovascular deaths or deaths from any cause. However, eating more ALA probably reduces the risk of heart irregularities from 3.3 to 2.6 percent. The review team found that reductions in cardiovascular events with ALA were so small that about 1000 people would need to increase consumption of ALA for one of them to benefit. Similar results were found for cardiovascular death. They did not find enough data from the studies to be able to measure the risk of bleeding or blood clots from using ALA.
Increasing long-chain omega 3 or ALA probably does not affect body weight or fatness.
Cochrane lead author, Dr. Lee Hooper from the University of East Anglia, UK says: “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 (fish oil, EPA or DHA) supplements does not benefit heart health or reduce our risk of stroke or death from any cause. The most trustworthy 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, it is unclear from the small number of trials whether eating more oily fish is protective of our hearts,” Hopper says
“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, 143 people would need to increase their ALA intake to prevent one person developing arrhythmia. One thousand people would need to increase their ALA intake to prevent one person dying of coronary heart disease or experiencing a cardiovascular event. ALA is an essential fatty acid, an important part of a balanced diet, and increasing intakes may be slightly beneficial for prevention or treatment of cardiovascular disease,” Hopper states.
