Wonder drug or waste of money? The truth about fish oil supplements

Fish oil is a perennial wellness topic, partly because there’s so much conflicting information.

“People perceive fish oil to be a wonder supplement,” says Amelia Sherry, clinical nutrition coordinator at the Mount Sinai hospital.

Fish oil supplements are high in omega-3s, essential fatty acids that our body does not produce on its own. These play an important role in cardiovascular health, brain function, eyesight and immune systems. As a result, fish oil supplements have been touted as a way of reducing the risk of heart attacks and inflammation, and improving cognitive function and skin health.

This has made fish oil supplements a booming business. Omega-3 supplements are some of the most popular nutritional supplements in the US and UK, and estimates put the value of the global fish oil market around $3.1bn.

But the scientific data isn’t as emphatic. A 2018 meta analysis found that taking fish oil supplements “does not benefit heart health or reduce our risk of stroke or death by any cause”. Last year, a study found that fish oil may increase risk of heart conditions and stroke for those without cardiovascular disease. Also, a lot of fish oil supplements seem to be rancid.

We asked experts what to know about fish oil supplements.

What are fish oil supplements?

Fish oil for supplements is extracted from fatty fish such as mackerel, salmon, herring, sardines and anchovies.

This oil is rich in two types of omega-3 fatty acids: eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA).

“Aside from fish, seaweed and algae are the only other sources of these two types of omega-3s,” Sherry says.

In supplement form, fish oil is often sold as soft gel capsules. However, what each supplement contains – say, how much EPA and DHA are in each pill – is not consistent. In the US, dietary supplements are not regulated by the Food and Drug Administration, explains Dr Stephen Kopecky, a cardiologist at the Mayo Clinic. (Supplements are regulated in the UK.)

“You’ve got to turn the bottle around to look at the ingredient label,” Kopecky says. Companies, he warns, “can change their labels week to week”.

What are the benefits of fish oil supplements?

Experts say it is important to differentiate between the benefits of eating fish and the benefits of consuming fish oil supplements. Omega-3s in fish have been shown to help reduce inflammation and plaque formation, lower blood pressure and triglycerides – a type of fat in the blood – and stabilize and protect cell members in the heart and brain, says Sherry.

But nutrition is complicated. Kopecky says it is unclear whether these benefits come from the omega-3s alone, or a combination of the fatty acids and the way the fish was caught, prepared and served. “There’s all these other factors,” he says.

The current fish oil boom is partly attributable to a 1985 paper in the New England Journal of Medicine, says Dr Steven Nissen, a cardiologist at the Cleveland Clinic.

The paper found that “mortality from coronary heart disease was more than 50 percent lower among those who consumed at least 30g of fish per day than among those who do not eat fish”.

Indeed, says Nissen, people who eat more fish tend to have better health outcomes. But it’s probably not just because they consume more omega-3s.

“If you eat more fish, you probably eat less meat,” he says, adding that populations that eat more fish tend to be more health conscious overall.

When it comes to fish oil supplements, Sherry notes that there is “some strong evidence” that fish oil can help people with pre-existing heart disease and high triglycerides. At the same time, she adds, “there has also been some research that shows no benefits and even some harm”. More study is needed on specific dosages and formulations, she says.

If you do have high triglycerides or cardiovascular concerns, experts suggest you talk to a doctor before taking fish oil supplements. Prescription fish oil is available, says Sherry, and tends to be more regulated than over-the-counter supplements.

What are the risks of fish oil supplements?

Some studies have found that potent fish oil supplements can put people at higher risk of atrial fibrillation – an irregular heartbeat that can lead to blood clots, stroke and heart complications. One trial of 13,076 patients was halted in 2020 “based on evidence of a low chance of clinical benefit and a statistically significant increase in atrial fibrillation”.

There are less serious potential side effects as well, says Sherry, such as burping, heartburn and stomach upset.

“The main side effect is they can burp a fishy taste,” says Kopecky.

How can you get the benefits of fish oil without taking supplements?

It’s quite simple: eat fish. “Eating more fatty fish in the place of proteins that are high in saturated fats would offer many more benefits than popping a fish oil supplement,” says Sherry.

Kopecky says if someone doesn’t eat a varied and nutritious diet, supplements of any kind are unlikely to help them.

The story of a fish oil supplements is “a microcosm of our world”, says Kopecky. “We find some food that’s beneficial for us, we say we know exactly what part is beneficial and we reduce it, desiccate it, put it in a pill, and sell it to you for 10 times as much money.”