It started in August 1970, when two Danish scientists ventured 500km (311 miles) north of the Arctic Circle to the Inuit settlements on the northwest coast of Greenland.
From these small fishing communities, Hans Olaf Bang and Jørn Dyerberg hoped to learn the secrets to a healthier life – in particular, to fending off heart disease. The Inuit, they’d heard, hardly ever suffered from this.
After collecting blood and food samples from a settlement’s 140 inhabitants, they drew one major conclusion. The secret to Inuit heart health? The omega-3 fatty acids in their marine-based diet.
The conclusion triggered decades of research on omega oils and a drive to encapsulate the benefits of fish oils in a supplement pill.
If it’s a story that sounds too good to be true, then it’s because it is.
It turns out that Bang and Dyerberg used unreliable records to estimate heart disease rates; recent studies suggest the Greenlandic Inuit were probably afflicted by the condition to the same extent as mainland Danes.
Omega oils are healthy. In fact, the benefits of our recommended portions of ‘fatty fish’ may extend beyond heart disease to other big killers like cancer, not to mention ageing itself.
But the science is more complicated than the early studies made it seem, and whatever fatty fish do offer us in terms of health we probably can’t get it simply by swallowing a pill.
So, if you’re unsure whether you’re getting enough, or worried you wouldn’t know a fatty fish if it slapped you in the face, here are the science-backed answers to your top questions about omega oils.
But first – what really are they, and how do they work?
Fats unpacked
Fats may have a bad reputation, but they’re vital to life. They supply energy and structural support to our cells, and act as molecular messengers in our immune and circulatory systems.
Fatty acids are the smaller building blocks needed to assemble fats and they come in two types: saturated (in solid animal fats like butter) and unsaturated (in liquid oils from plants and fish, like the omegas).
We tend to think ‘saturated’ and ‘unsaturated’ reflect healthiness, but as Prof Alice Lichtenstein, director of the cardiovascular nutrition team at Tufts University, near Boston in the US, explains, they’re actually chemical terms that tell us about the carbon backbones of fatty acids.
“It means that for saturated fatty acids, all the carbon atoms are linked together quite simply in a straight line,” she says.
“For unsaturated fatty acids, there’s a double link between some of them. And when there’s a double link, there’s an angle – like a knee that doesn’t straighten.”
These kinks prevent the fatty acids in omega oils from packing close enough together to form solid fats, while also determining what type of omegas they are. In omega-3s, the first kink is at the third carbon in the chain, while in omega-6s it’s at the sixth.
Fish form a central part of Greenlandic Inuit diets, but what role this plays in heart health is still mysterious – Image credit: Alamy
The differences are important as, according to Lichtenstein, they dictate the shape of fatty acids and therefore which molecules in our bodies they interact with. “Our enzymes are very specific,” she notes.
Another important distinction is between ‘essential’ (omega-3 and 6) and ‘non-essential’ (omega-9 and saturated) fatty acids.
Our bodies can’t make essential fatty acids from scratch, so we can only get omega-3s by eating long-chain eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in seafood, or short-chain alpha-linolenic acid (ALA) in plants.
Omega-6s (linoleic acid and arachidonic acid) are in copious supply in processed foods and cooking oils such as sunflower and corn oil, so we rarely struggle to get enough.
Surprisingly, fish don’t actually make omega-3s or 6s either. They get them from marine algae, which mainline omega-3s to everything further up the food chain – including the seals and whales in Inuit diets.
Some of these tiny blob-like organisms are almost half fats and oils by weight and are emerging as vegetarian omega-3 supplements.
Help for the heart?
While we know we need omega oils, it’s still hard to be precise about how helpful they are. Take one 2024 study, for example, which looked at blood levels of DHA in around 118,000 people involved in the UK Biobank study (a major, decades-long health survey).
When participants were split into five groups by DHA level, those with the highest levels were 21 per cent less likely to die within 13 years compared to those with the lowest.
These results are encouraging, although we can’t place too much weight on them because people who eat more fish, or take supplements, tend to have other healthy habits like exercising or not smoking.
Studies like this one can’t establish cause and effect, just an association between omega oils and health. And even if trials are set up to eliminate these problems, it’s practically impossible to isolate the effects of omega fatty acids from the wider benefits of eating fish.
After all, you can hardly create a convincing placebo when the intervention is a plate of pollock.
A dietary boost of omega oils could help you stay healthy for longer, if integrated into a healthy lifestyle generally – Image credit: Getty Images
It’s easier to isolate the effects of supplements. But the results have been unimpressive – and sometimes confusing. A widely cited 2020 review, mostly of supplement trials, found very little benefit of taking omega-3 supplements.
But then in 2021, a new review focusing solely on the supplement trials (excluding the few offering dietary advice) suggested supplements could reduce the risk of heart disease-related events by 9 per cent and heart attacks by 13 per cent.
Co-author of the 2021 paper cardiologist Prof Carl Lavie of the University of Queensland, in Australia, argues that his and some other reviews suggest these risk reductions are “not dramatic” but still important.
Lavie, though, admits there are issues with supplement trials too. For example, clinical events like heart attacks can be rare during trials, so there’s little data to support the role of omegas either way.
But does that mean we should dismiss advice on getting more omegas in our diets? No.
Besides research in cells and animals that suggests plausible benefits, we know that omega-containing fish and plants are healthier than most other things we could be eating.
Read more:
Action on ageing
Omega fatty acids provide fluidity to the membranes surrounding our cells, help us absorb vitamins, and form the skeletons of signalling molecules called eicosanoids that are involved in essential processes like blood flow and clotting, pain and temperature control, and our responses to infection and injury.
For biological processes, it’s the longer, fishy EPAs and DHAs we need, although our bodies can construct them – in small quantities – from the shorter, plant-based ALAs. “Somebody can live a normal, healthy life without eating fish,” says Lichtenstein.
Studies suggest consuming omega oils could help protect against heart disease by reducing excess fats called triglycerides in your blood, and boosting your ‘good’ cholesterol (high-density lipoprotein or HDL).
HDL helps to remove low-density lipoprotein (LDL) – the bad, artery-clogging type of cholesterol – from the bloodstream.
There’s also good evidence, says Prof Marc Gunter, chair in cancer epidemiology and prevention at Imperial College London, that these fatty acids could reduce the risk of other diseases including cancer because of their anti-inflammatory effects.
This is especially the case for protection against bowel cancer – though, he adds, the effects of fish seem more apparent than supplements.
Some scientists argue that omega-3’s anti-inflammatory effects slow the ageing process itself, at least at a cellular level. One 2025 study based on 144,000 people involved in the Biobank survey found that those who had more omega-3s and fibre in their diets had longer telomeres.
Telomeres are the caps on chromosomes, which slowly wear down during our lifetime and can be used to estimate age. It’s thought they wear down partly due to a build-up of inflammation.
Telomeres display telltale signals of ageing via their length – Image credit: Getty Images
In their study, the researchers calculated that for every 1 per cent of their energy people got from omega-3s instead of saturated fat, the difference in telomere length was equivalent to about a year. For omega-6s, the difference was around three months.
What’s more, the risk of age-related diseases like dementia and heart disease also increases with telomere length. So these findings may help explain potential effects of omega-3s on a range of chronic conditions as we get older.
Telomere length isn’t the only way to gauge biological age. Other scientists use ‘biological clocks’ based on chemical alterations to DNA, known as epigenetic changes, which accumulate over time.
A 2025 study published in Nature using biological clocks found that, in the over 70s, taking 1g per day of omega-3 supplements (from marine algae) slowed the pace of ageing by more than a couple of months over three years.
It’s not yet known whether these effects are sustained in the long term – after all, we can’t expect to halt ageing altogether.
But ageing did slow even more when omega-3s were combined with vitamin D and exercise, emphasising that the best results won’t come from simply popping a pill.
Instead, we need to be thinking more broadly, taking what Gunter calls “a more holistic viewpoint” that looks at what we eat and how we move.
So, without further ado, here the experts answer your top questions on omega oils.
1. Should I eat more fish?
Yes, if you like fish and you’re not a vegetarian (more on this later). Eating fish covers more bases than a supplement because, as well as omega-3s, it’s packed with protein, makes a good swap for meats high in saturated fats, and comes with useful vitamins and minerals.
While we don’t know if the benefits are strictly due to the omega-3s or the whole package, there’s certainly compelling evidence for swapping some meat for fish.
A recent review of 95 studies, for example, suggests that people who eat more fish are less likely to develop colon, rectal and bowel cancers, while those who eat more red meat are at increased risk of most types of bowel cancer.
One possible downside is the volume of toxins that accumulate in fish due to ocean pollution, but experts say that, at recommended levels, eating most fish should be safe.
Grilled fish is a great way to introduce more omega oils into your diet – Image credit: Getty Images
“A couple of portions a week seems to be beneficial,” says Gunter. “But I think it’s like anything: with excessive amounts, it’s probably not good.”
In line with this thinking, recommendations across many countries suggest between one to three portions a week, including some fatty fish like salmon or mackerel.
Pregnant women are encouraged to continue eating fatty fish, because omega-3s help babies’ nervous systems develop, but to avoid excessive amounts.
According to Lichtenstein, though, since most of us don’t eat enough fish, we could keep it even more basic. “Initially, my recommendation would be to start eating more,” she says. “Not deep-fried fish and chips but, in general, more fish – whatever type you like.”
2. Can’t I just take supplements?
While we know that a wholefood diet containing omega-3s and 6s is beneficial, the evidence for supplements is fairly disappointing.
Any benefits for heart health or cancer seem small, and independent reviews published by the Cochrane Library in the last five years found no or very limited evidence for omega-3 supplements in reducing stroke, depression, ADHD and nerve issues linked to diabetes.
That said, if you want to take a supplement, here are some things to bear in mind.
Fish oil supplements go rancid when fatty acids react with oxygen, meaning EPA and DHA diminish, presumably along with their effects.
A 2015 study testing 32 fish oil supplements sold in New Zealand found only three contained the stated quantities of omega-3s, with most exceeding recommended oxidation levels.
There are no regulations to prevent this, so look for products that voluntarily declare their ‘TOTOX’ (total oxidation) value, certified by an independent lab. And don’t let them languish in your cupboard for years.
More worryingly, some recent reports suggest a link between omega-3s and atrial fibrillation (irregular heartbeat), but mainly at higher levels. “For most [people], keep the EPA and DHA below 1,000 mg per day,” says Lavie, who argues that any risk is likely minor enough to be balanced out by other heart benefits.
Perhaps the biggest risk is that they don’t work – particularly if they’re used instead of reliable drugs.
For heart disease, for example, we know that statins effectively lower cholesterol and we shouldn’t assume we can get the same benefits from supplements. But there’s probably little harm in taking both in this case.
3. Are fish oil supplements sustainable?
Here we get into choppy waters because it’s well known that wild fish – and marine species more broadly – face huge pressures from fisheries.
The Food and Agriculture Organization (FAO) of the United Nations estimates that over a third of marine stocks are fished at unsustainable levels. At the same time, however, hundreds of millions of people rely on fisheries for their livelihoods.
For advice on getting your omega-3s from sustainable sources, refer to guides by the Marine Conservation Society’s Good Fish Guide if you’re in the UK and Monterey Bay Aquarium’s SeafoodWatch if you’re in the US.
The FAO considers fish farming a more sustainable option for meeting growing demand and is aiming to increase production by at least 35 per cent by 2030, meaning we may end up getting more of our omega-3s from farmed fish.
And according to Lichtenstein, we shouldn’t worry about it being any less healthy. “It’s a myth,” she says. “I don’t think there is any data that supports that.”
4. But wait, I’m a vegetarian…
If you don’t eat fish, vegan sources of omega oils include tofu, walnuts and flaxseeds – Image credit: Getty Images
The main source of omega-3s for vegetarians (and vegans) is ALA, found in higher levels in certain nuts and seeds, like walnuts and flaxseeds, as well as in rapeseed (or canola) oil and green vegetables including broccoli.
While you’re very unlikely to go short on omega-6s, good sources include sunflower oil and tofu.
Unfortunately, dietary guidelines often make no special recommendations for vegetarians on omega-3s, and research into dietary intakes and plant-based supplements is scarce.
In 2021, UK researchers who reviewed evidence from 13 different studies in vegetarians and vegans saw promising effects of microalgal oil supplements for raising omega-3 levels, but in only three small trials, while high doses of flaxseed oil and echium proved ineffective.
Vegetarians may have lower levels of omega-3s, but you’re unlikely to have a problem if you take more care over what you eat.
In fact, overall, you may be better off because you eat less red meat. In the end, it’s about big picture thinking. A fish oil supplement probably won’t change your life, but eating more mindfully might.
Read more:
