Omega-3 oils, typically found in oily 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 although fish oil supplements may reduce the risk for those who already have cardiovascular disease, they may increases the risk of someone developing heart disease or stroke in the first place.
Why do we need omega-3s?
Omega-3s are essential fatty acids, which are important for your health. Your body can’t make it, so you have to get it from your diet. There are three main types of omega-3s. Alpha-linolenic acid (ALA) is necessary for our bodies to make eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). EPA and DHA are important for your heart, blood vessels, lungs and the immune and hormone systems. DHA is also important for the development of the retina, brain and nervous system in babies.
But since we can only convert small amounts of ALA into EPA and DHA, we must eat foods that contain them.
OK, so how do I get omega-3s?
Oily fish such as mackerel, salmon and sardines are a rich source of EPA and DHA omega-3s. White fish such as cod, haddock and haddock, and shellfish also contain omega-3s, but at much lower levels than oily fish. If you don’t eat fish, you can get omega-3s from flaxseeds, chia seeds, walnuts, rapeseed, 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 rather than eating fish?
Current guidelines recommend the latter.
The NHS recommends eating at least one serving of oily fish per week to help prevent the development of cardiovascular disease. However, pregnant women or those who are breastfeeding should not consume more than two servings or 140g per week.
In contrast, in the United Kingdom, National Institute for Health and Care Excellence guidelines do not recommend the use of omega-3 supplements to prevent cardiovascular disease or prevent another heart attack unless your family doctor prescribes them for high levels of triglycerides.
The British Dietetic Association, which represents British dietitians, says: “Omega-3 supplements are not recommended in the general population of the UK. This is because evidence of benefits is inconclusive.”
What about this new study?
Briefly, a team of researchers monitored the health of more than 400,000 participants in the UK Biobank (a biomedical database) for an average of 12 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 conditions.
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 having a stroke. But the study also showed that these supplements were associated with a 15% lower risk of progressing from atrial fibrillation to a heart attack, and a 9% lower risk of progressing from heart failure to death.
But this study only looked at omega-3 supplements, so we can’t tell you about the risks and benefits of eating oily fish itself.
How does it fit with other research?
Previous studies found little or no evidence that supplements containing the omega-3s EPA and DHA lowered the risk of heart attack, stroke, or death from heart disease.
And a large study done in the US found that fish oil supplements were only beneficial for people who did not eat fish.
However, studies have found high levels of omega-3s are associated with lower risks of dementia – although how participants got these omega-3s is not clear, and the study does not prove cause and effect – while research suggests that consuming oily fish helps reduce inflammation and pain for patients with rheumatoid arthritis and lupus.
Research from 2022 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, an emeritus professor of nutrition and dietetics at King’s College London, said small amounts of long-chain omega-3 fatty acids allowed health claims for maintaining a healthy heart and for normal brain and visual development in infants.
But he said trials related to heart disease prevention were mainly in people with type 2 diabetes or those who had a cardiovascular event. What’s more, while high doses of fish oil supplements have been associated with reduced cardiovascular mortality, most trials using lower doses show no such benefit.
“Current guidelines for the prevention of cardiovascular disease encourage fish consumption, but not fish oil supplements,” he said.
Nathan Davies, the clinical nutrition program lead 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 NHS advice to eat oily fish on a weekly basis is beneficial in relation to omega-3 intake, vitamin D and other micronutrients,” he said.
“Where people have specific dietary requirements, supplements can be beneficial, but for the vast majority of the population it is much better to eat a varied diet.”
However, Davies said it is not necessary for someone to take omega-3 supplements to stop it.
And if you’re concerned about your heart, you should seek medical advice and not try to self-medicate with supplements, he added.
