Every day, millions of people from around the world take fish oil supplements in hopes of protecting them from heart disease. But do these golden capsules really work? A large systematic review is being investigated.
Omega-3 is a type of fat found in fish, seafood, certain nuts, and vegetable oils.
In particular, there are three main types of omega-3 fatty acids: alpha linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA).
ALA is an essential fatty acid, which means that the human body cannot produce it on its own and has to get it from food.
Flaxseed, soybean and rapeseed oils, as well as chia seeds and walnuts, contain ALA.
DHA and EPA – also known as long-chain omega-3 fatty acids – are found in fatty fish such as salmon, mackerel, tuna, herring, and sardine, as well as in other types of seafood.
Studies have shown that those who regularly consume fish as part of a healthy, balanced diet are at lower risk of heart problems. However, the National Institutes of Health (NIH) state that it is unclear whether these benefits come from fish or omega-3s in particular.
While the judges are not informed yet, millions of people in the US have turned to omega-3 fatty acids or fish oil supplements for their alleged heart health benefits.
According to a survey by the NIH, “In 2012, fish oil was the most popular natural product used by adults in the United States”. About 18.8 million Americans took part.
But are the supplements actually worth the hype? A new review by researchers from Cochrane, an independent organization that evaluates existing medical research, evaluates the benefits of the supplements based on the evidence available.
Lee Hooper, lead author of the meta-analysis, is a systematic reviewer and reader on research synthesis, nutrition and hydration at Norwich Medical School, University of East Anglia in the UK
The results are now published in the Cochrane Library.
Hooper and colleagues reviewed 79 randomized trials involving a total of 112,059 participants. The studies evaluated the cardiovascular effects of taking omega-3 supplements and compared them to those of normal or lower intake of omega-3.
In most of the studies, some participants received fish oil supplements while others took placebos.
Other studies prompted participants to increase their omega-3 intake over a period of one year, while other participants were asked to leave them unchanged.
The majority of studies evaluating the effects of ALA intake found that participants in the intervention group included foods fortified with omega-3s, such as margarine or foods naturally rich in ALA, including walnuts. The control group had a normal, non-fortified diet.
The review found that taking long-chain omega-3 supplements had “little or no effect” on the risk of death from causes, the risk of death from cardiovascular problems, or the risk of death from coronary artery disease.
The supplements are also reported to have “little or no effect” on the risk of cardiovascular events, stroke, or irregular heartbeat.
As for ALA, increasing consumption of walnuts or fortified products such as margarine “is unlikely to make any or little difference to all cause deaths or cardiovascular disease or coronary events, but is likely to decrease slightly[s] cardiovascular events, coronary mortality, and heart irregularities, ”conclude the authors.
However, that reduction is so small that 1,000 people would have to increase their ALA intake for either of them to benefit, the researchers say.
This is based on “moderate and good quality evidence”. Conversely, “earlier suggestions on the benefits of EPA and DHA supplements seem to come from studies with a higher risk of bias,” the authors write.
Finally, the effects of ALA on stroke risk remain unclear as the evidence has been classified as “very poor quality”.
Commenting on the results, Hooper said, “We can rely on the results of this review, which violate the popular belief that long-chain omega-3 supplements protect the heart.”
“The review provides good evidence,” she adds, “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 for any reason.”
“The most trustworthy studies have consistently shown that long-chain omega-3 fats have little or no effect on cardiovascular health,” says Hooper. “On the other hand, oily fish is a healthy food, but the small number of trials does not show whether eating oily fish protects our hearts.”
In an expert reaction to the review, Tim Chico, professor of cardiovascular medicine and volunteer cardiologist at the University of Sheffield in the UK, says: “While diet is important in preventing heart disease, it is complex and unlikely to that something relates to a single element of nutrition. “
“Previous experience has shown that while some types of diets are associated with a lower risk of heart disease, when we try to identify the beneficial element of the diet and add it as a supplement, it generally has little or no benefit. “
Prof. Tim Chico