Flogging fish oil supplements is a lucrative business. In the United States only, 19 million people take the pills, spend $1.2 billion per year on them. Early studies suggested it was money well spent. Omega-3 fatty acids have been shown to help maintain a healthy heart. However, a few recent studies seem to contradict this. Does that mean omega-3 fish oil supplements are a waste of money? Let’s take a closer look at the evidence.
Omega-3 fatty acids are a group of essential polyunsaturated fatty acids. They are called “essential” because we need them to function but our bodies cannot manufacture them. We rely on sources such as fish and shellfish, or supplements, to get enough. Supplements typically contain two important types of omega-3s: eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA).
Evidence from early clinical trials has shown that omega-3 fatty acid supplements can reduce the risk of cardiovascular disease. In 2002, an analysis of data from the GISSI Prevention Trial showed that omega-3 fatty acids reduce the risk of further damage in people who have suffered a heart attack.
The researchers randomly assigned about 11,000 people who had had a heart attack to 1 g daily of omega-3 fatty acids or a placebo for three and a half years. Compared to those assigned to take a placebo, people who took the omega-3 supplement had a 20% reduced risk of death during the follow-up period, a 15% reduced risk of non-fatal heart attack, a 30% reduced risk of cardiovascular death and a 45% reduction in the risk of sudden cardiac death.
And, in 2007, a large Japanese studyinvolving nearly 19,000 participants, showed that omega-3 fatty acids lead to 19% risk reductions in major cardiovascular events, such as heart attacks and strokes.
More recently (2016), researchers at Stanford University analyzed the data from 19 studies including nearly 46,000 people from 16 countries. Over time, 7,973 participants suffered their first heart attack, of which 2,781 died. The researchers found that people who had higher levels of omega-3s in their blood were about 10% less likely to die of a heart attack than people who had lower levels of omega-3s.
Another recent study (2016) showed that omega-3 fatty acids help heart muscles recover after a heart attack. Researchers at Harvard Medical School found that, compared to those taking a placebo, participants taking a high dose of prescription-grade omega-3 fatty acids (4 g per day), for six months, had less scarring on their heart muscle and an increased ability to pump blood. The study also found that the more omega-3s the body absorbed, the better the heart pumped.
Recent trials seem less certain
However, not all trials investigating the benefits of fish oil supplements on heart health have shown positive results. Several reasons for these negative results has been proposedincluding short treatment periods, relatively low doses of omega-3 fatty acids, small sample sizes (“underpowered” studies as they are called), and concurrent use of drugs to prevent cardiovascular disease, like statins.
olive oil, which helps prevent cardiovascular diseasehas been used as a placebo in some of the clinical trials that showed no additional beneficial effects of omega-3s on heart health. In all trials that showed no benefit from omega-3 fatty acids, only a small amount of omega-3 fish oils (380-840 mg) was used, while the current recommendation (which is used in major ongoing clinical trials) is 2-4g per day.
Thus, negative results from these trials do not necessarily prove that omega-3 fatty acids are ineffective in preventing cardiovascular disease – they only demonstrate that they were not effective in the context in which they were tested.
Two large ongoing clinical trials using high-dose prescription omega-3 fatty acids are examining the cardiac benefits of omega-3 supplementation in generally healthy low-risk groups, as well as in high-risk groups in the whole world. The results of the REDUCE-IT trial will be available in 2018 and the FORCE test will be completed around 2020. I am confident that they will provide further evidence that omega-3s are good for the heart in both sick and healthy people.
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Even if future trials fail to show a benefit for fish oil supplements, no harm has been done, right? After all, they are a natural supplement. Well, not quite.
The EPA and DHA used in clinical trials were of a prescribed purity and strength. But with the lack of regulation of dietary supplements, many omega-3 capsules not include all nutrients they claim and are sometimes charged with additional saturated fat. Some are even contaminated with levels of carcinogens that exceed US Environmental Protection Agency standards. EPA and DHA levels can also vary widely within and between brands, with many containing only half the amounts of EPA and DHA indicated on the label.
Omega-3s are very vulnerable to degradation during manufacturing and become oxide (rancid) during transport and storage. Once they are broken down, they no longer have their favorable benefits and, in fact, are poisonous. Earlier this year, a study from Harvard Medical School found that three popular American brands of omega-3 fish oil supplements contained highly oxidized products that exceeded maximum levels set by international quality standards.
Unlike buying a piece of salmon from a store where you can smell and examine the product for freshness, you can’t do that with a bottle of fish oil supplements. Anyone wanting to get their fill of this healthy fatty acid is advised to get their daily dose from fishmongers, not pharmacies.
