They’re the fishy, golden capsules that help protect against heart disease, minus the unpleasant aftertaste – or so we’re told.
But a recent study has found that fish oil supplements have little effect in heart disease patients, sparking fresh debate about whether we should focus on eating the real thing instead.
Fish oils contain omega-3 fatty acids, a type of polyunsaturated fat needed for good heart health. Our bodies cannot produce omega-3s on their own so they must be sourced through our diet.
Studies have shown a diet rich in omega-3s is linked to lower rates of heart disease. But the evidence for bottled fish oil – the second most-popular supplement after multivitamins, according to the 2014 national health survey – has been mixed.
“Use of fish oils is widely promoted as having magic health benefits but the science to support this, based on the highest levels of research, is very limited,” says Craig Anderson, a global researcher in cardiovascular disease and senior director at the George Institute.
For this most recent study, researchers analysed data from 10 trials. They involved 77,917 participants who took fish oil supplements for at least one year, some for up to six years. Most participants had a history of heart disease, stroke or diabetes, and their average age was 64.
During the study period, there were 31,561 heart-related complications among the group, including major vascular events, heart bypass or angioplasty, stroke, and deaths caused by coronary heart disease.
The study’s results were published in JAMA Cardiology.
“The results provide no support for current recommendations to use omega-3 fatty acid supplements for the prevention of fatal coronary heart disease or any cardiovascular disease in people who have or at high risk of developing cardiovascular disease,” the authors wrote.
Michael Skilton, a cardiovascular health associate professor at the University of Sydney, says there is some evidence to suggest that fish oil does have a role in heart health.
“In older adults with existing heart disease, there is no strong indication that omega-3 supplements are beneficial for preventing future heart attacks or strokes,” he says.
“But the results for death from heart disease were less clear cut, with borderline evidence that omega-3 supplements may be beneficial.”
A 2016 analysis of 19 international studies found that people with higher concentrations of omega-3 in their blood had a slightly lower chance of dying from a heart attack.
Dr Kellie Bilinski, an accredited practising dietitian and spokesperson for the Dietitians Association of Australia, says the low dose of omega-3s in the trials provides a possible explanation for the conflicting results.
“They [researchers] looked at one gram a day of omega-3 … generally, we know with cardiovascular disease you need three to four grams for it to be beneficial,” she says.
In 2015, the Heart Foundation updated its position statement on fish oil and heart health. “We do not advise routine recommendation of omega-3 supplements for heart health by health professionals,” Professor Garry Jennings, the foundation’s chief medical adviser and a cardiologist at Alfred Health, said.
Instead, the foundation recommends eating two to three servings of fish a week. That is consistent with recommendations from Food Standards Australia New Zealand, the National Health and Medical Research Council and the DAA.
The best source of omega-3 is from oily fish, including salmon, blue-eye trevalla, blue mackerel, herring, canned sardines and salmon and some types of canned tuna. Other good sources include barramundi, bream, flathead, squid, scallops and mussels.
“It’s always good to meet your nutrient requirements by food, if you can,” Dr Bilinski says.
“Supplements can have a place in a healthy diet when food is not a possibility. Some people are allergic to fish, as well, and they really don’t have an option.”
Other foods containing small amounts of omega-3 include walnuts, linseeds, eggs, chicken and beef.