Is omega-3 oil good or bad for us – and does it matter where it comes from?
Omega-3 oils, commonly found in fatty fish and fish oil supplements, are often said to have numerous health benefits, such as reducing the risk of heart attacks, dementia and joint pain.
But recently research published in the journal BMJ Medicine shows that while fish oil supplements may reduce the risk for those who already have cardiovascular disease, they may increase the risk of someone developing heart disease or stroke in the first place.
Why do we need omega-3 fatty acids?
Omega-3 fatty acids are essential fatty acids that are important for your health. Your body cannot produce them, so you must get them from your diet. There are three main types of omega-3 fatty acids. Alpha-linolenic acid (ALA) is necessary for our body to make eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). EPA and DHA are important for your heart, blood vessels, lungs and immune and hormone systems. DHA is also important for the development of the retina, brain and nervous system in babies.
But because we can only convert small amounts of ALA into EPA and DHA, we must eat foods that contain these substances.
Okay, so how do I get omega-3s?
Fatty fish such as mackerel, salmon and sardines are a rich source of EPA and DHA omega-3 fatty acids. White fish such as cod, haddock, plaice and shellfish also contain omega-3 fatty acids, but at much lower levels than oily fish. If you don’t eat fish, you can get omega-3 fatty acids from flaxseeds, chia seeds, walnuts, canola, soybeans and the oils made from them.
But many people take fish oil supplements or vegetarian omega-3 supplements, which contain microalgae oil.
Does it matter if I take supplements instead of eating fish?
Current guidelines recommend the latter.
The NHS recommends eating at least one portion of oily fish per week to help prevent the development of cardiovascular disease. However, pregnant or breastfeeding women should not consume more than two servings or 140 grams per week.
In Britain, on the other hand Guidelines from the National Institute for Health and Care Excellence do not recommend the use of omega-3 supplements to prevent cardiovascular disease or another heart attack unless your doctor prescribes them for high triglyceride levels.
The British Dietetic Association, which represents UK dietitians, says: “Omega-3 supplements are not recommended in the general population of Britain. This is because the evidence of benefit is inconclusive.”
What about this new study?
In short, a team of researchers monitored the health of more than 400,000 participants in the UK Biobank (a biomedical database) for an average of twelve years. They looked at the impact of taking fish oil supplements on developing heart conditions such as atrial fibrillation (irregular heartbeat), heart attack, stroke and heart failure. They also assessed whether these supplements affected the progression of heart disease.
They found that regular use of fish oil supplements was associated with a 13% increased risk of developing atrial fibrillation and a 5% increased risk of stroke. But the study also showed that these supplements were associated with a 15% lower risk of atrial fibrillation progressing to heart attack, and a 9% lower risk of heart failure progressing to death.
But this study only looked at omega-3 supplements, so it can’t tell us about the risks and benefits of eating oily fish itself.
How does this fit in with other research?
Previous studies have found little or no evidence that supplements containing the omega-3 fatty acids EPA and DHA reduce the risk of heart attack, stroke or death from heart disease.
And a large study in the US found that fish oil supplements were only beneficial for people who did not eat fish.
However, research has shown that there is a link between high levels of omega-3 fatty acids lower risks of dementia – although it is not clear how participants obtained these omega-3 fatty acids, and the study does not prove cause and effect – while research shows that consuming oily fish help reduce inflammation and pain for patients with rheumatoid arthritis and lupus.
2022 study found that among older adults, taking regular fish oil supplements was significantly associated with a lower risk of all-cause dementia, as well as vascular dementia, frontotemporal dementia and other dementias, but not Alzheimer’s disease.
Should I stop taking omega-3 supplements or start eating oily fish?
Tom Sanders, emeritus professor of nutrition and dietetics at King’s College London, said small amounts of long-chain omega-3 fatty acids had allowed a health claim for maintaining a healthy heart and for normal brain and visual development in infants.
But he said studies related to heart disease prevention have mainly been conducted in people with type 2 diabetes or in people who have had a cardiovascular event. Furthermore, although high doses of fish oil supplements have been associated with reduced cardiovascular mortality, most studies using lower doses do not show such a benefit.
“Current guidelines for cardiovascular disease prevention encourage fish consumption, but not fish oil supplements,” he said.
Nathan Davies, head of clinical nutrition programs at University College London, said there is no evidence that eating fish is harmful to health.
“Eating a healthy diet is always preferable to taking supplements, and following the NHS advice to eat fatty fish weekly is beneficial in relation to intake of omega-3, vitamin D and other micronutrients,” he said.
“Where people have specific nutritional needs, supplements can be helpful, but for the vast majority of the population it is much better to eat a varied diet.”
However, Davies said there was no need for anyone to stop taking omega-3 supplements.
And if you are concerned about your heart, you should seek medical advice and not attempt to self-medicate with supplements, he added.