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Omega-3 supplements offer little or no protection against heart disease, stroke or early death

When the fish oil is snake oil.

After analyzing the results of several dozen of the best studies on the topic, the Cochrane researchers found that omega-3 supplements have little or no effect on reducing the risk of heart attacks, stroke or early death.

Omega-3 supplements have been widely promoted as offering protection against a range of illnesses, including heart attacks, stroke and other types of cardiovascular disease.

Such claims have led almost 19 million American adults to take omega-3 supplements on a regular basis — and at an annual cost to their pocketbooks of more than $1 billion

A growing body of research suggests, however, that most of those people are just throwing away their money. The latest study to make this point was published last week by a team of independent experts working for the non-profit Cochrane organization.

After analyzing the results of several dozen of the best studies on the topic, the Cochrane researchers found that omega-3 supplements have little or no effect on reducing the risk of heart attacks, stroke or early death.

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“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,” said Lee Hopper, one of the study’s authors and an epidemiologist at the University of East Anglia, in a released statement. “This large systematic review included information from many thousands of people over long periods.”

“Despite all this information,” she added, “we don’t see protective effects.” 

Study details

As background information in the Cochrane study points out, all of us need small amounts of omega-3 fatty acids — alphalinolenic acid (ALA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) — to stay healthy. We get these fatty acids from our diet — from fatty fish (such as salmon, lake trout, mackerel, herring, sardines and tuna), as well as from certain plant foods (such as walnuts, flaxseed and soybeans).

In recent years, however, there has been a growing belief (promulgated in large part by the supplement industry) that taking omega-3 supplements helps reduce our risk of disease, particularly of various types of cardiovascular disease (ones involving the heart and blood vessels). 

The Cochrane researchers decided to conduct a meta-analysis to determine if the scientific evidence actually supports that belief. They examined data from 79 randomized controlled trials (considered the gold standard for medical studies) involving more than 112,000 people living in North America, Europe, Australia and Asia. These studies, which lasted from 12 to 14 months, assessed the effects of consuming additional omega-3 fatty acids — either by taking supplements or, in a few studies, by increasing the intake of omega-3-rich foods — on various aspects of cardiovascular disease. 

Twenty-five of the studies were considered at low risk of bias and thus highly trustworthy.

Key findings

The Cochrane reviewers looked specifically at whether the supplementation of omega-3 fatty acids had any effect on reducing the risk of irregular heart beat, coronary heart disease and death from heart attack, stroke or other cardiovascular-related causes.

They found that increasing omega-3 intake, either through capsules or diet, had little or no effect on most cardiovascular outcomes. Extra amounts of EPA and DHA did appear to slightly reduce blood levels of harmful triglycerides, but that was offset by a reduction of beneficial HDL cholesterol.

Nor did consuming more omega-3 significantly alter the risk of early death — from any cause. The data revealed, for example, that the risk of early death from any cause was 8.8 percent for the people in the studies who had increased their intake of omega-3 fatty acids. That compared with a 9 percent increase in risk for people who were in the studies’ control groups (who maintained their usual intake of omega-3 fatty acids during the duration of the studies). 

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The researchers did find moderate evidence that eating plant sources of fatty acids, particularly walnuts, reduced the risk of developing heart irregularities and cardiovascular-related deaths, but the observed effect was very small. 

Eat your veggies instead

Although it was a large meta-analysis (and, thus, a particularly rigorous look at the evidence), the Cochrane review comes with several limitations. For example, the studies all took place in high-income countries. Their findings may not be applicable, therefore, to people living in countries where access to omega-3-rich foods is more limited. 

Also, only a small number of the clinical trials had people increase their omega-3 intake by changing their diet rather than by taking supplements. So, although the meta-analysis found that eating more oily fish does not protect against cardiovascular disease, that finding is unclear. 

The meta-analysis’ message about omega-3 supplements, however, is not muddled. 

 “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,” states Hooper. “The most trustworthy studies consistently showed little or no effect of long-chain omega 3 fats on cardiovascular health.”

As Tim Chico, a professor of cardiovascular medicine at Sheffield University who was not involved in the Cochrane review, told the Guardian newspaper, we need to stop focusing on supplements to prevent heart disease.

“Previous experience has shown that although some types of diet are linked to lower risk of heart disease, when we try to identify the beneficial element of the diet and give it as a supplement it generally has little or no benefit,” he said. 

“Such supplements come with a significant cost,” he added, “so to anyone buying them in the hope that they reduce the risk of heart disease, I’d advise them to spend their money on vegetables instead.”

FMI: The meta-analysis was published in the Cochrane Database of Systematic Reviews.