Head to any pharmacy, make your way past sandwiches and make-up and towards the aisle labelled ‘vitamins and supplements’. You’ll soon spot them, rows and rows of them, each promising everything from a happier sex life to more comfortable bowel movements. Yet, even in a world shaped by miracle cures – one where the UK market alone stands at £550m and global annual compound growth is set at nearly 9% – you may still notice one that stands out more than the rest.

In a dozen different boxes, in a dozen different varieties – pills, capsules and oils – their ingredients veering from fish to vegetables and back again. Their list of supposed effects will be just as comprehensive, too, with each labelled bottle assuring punters that omega-3 can cure everything from lupus to eczema with the right help.

Since its initial discovery by Western scientists in the 1970s, omega-3 has been a stalwart of global healthcare. Once again, the statistics reveal there is more here. According to work by Data Bridge Market Research, for instance, the global industry for these fatty acids could reach $4.76bn by 2029. Certainly, they’re wildly popular already.

In the US, to give one example, an estimated 8% of adults actively take omega-3 in some form. Yet if the packaging says it can fight a bewildering range of ailments, there’s one area where the seduction of omega-3 remains unmatched: heart health. This appears to be the result of a certain American company, whose product is proudly called ‘Heart Health’ and tells readers in capital letters that it’s designed for ‘cardiovascular maintenance’.

“It is important for individuals with cardio vascular disease (CVD) to have adequate omega-3 intake, either from foods or supplements, to improve cardiovascular health.”
Professor Simin Liu

Of course, the particular allure of cardiovascular health isn’t difficult to understand. According to the WHO, 16% of all deaths worldwide are due to heart disease, meaning anything that offers to keep users safe is bound to be popular. Explore the specifics, however, and the situation soon becomes less straightforward – something even the manufacturers of ‘Heart Health’ are obliged to admit. Turn the box over and you’ll see a disclaimer noting its claim of ‘cardiovascular maintenance’ hasn’t actually been evaluated by the FDA.

That concession, in turn, hints at a broader truth: despite being recommended for some 50 years, what omega-3s can do for heart health remains uncertain. And beyond the fundamentals, other problems persist too. What form, for instance, is the best way to take omega-3? How does it interact with other nutrients to keep the body safe? None of these questions necessarily have simple answers – even as new research promises to offer exciting new insights.

The heart of the matter

Arguments around the precise link between omega-3 and heart health have been raging for decades. Since the first flush of optimism in the 1970s, when a team of Danish scientists uncovered the probable benefits of the fats among the natives of Greenland, Philip Calder says that “the pendulum has swung one way and another many times” over recent years.

Listen to the University of Southampton professor and it’s hard to disagree. Through the 1980s and 1990s, for example, Calder describes how a range of studies investigated whether measures like lipids and blood pressure could positively be linked to omega-3. Many researchers concluded that fatty acids could indeed keep blood pressure low, and along the way cut the risk of heart disease. From there, scientists moved on to look at people who had already suffered a heart attack, with one Italian study known as ‘GISSI-Prevenzione’ suggesting omega-3 could reduce the danger of having a second cardiovascular episode. More recent attempts to replicate that famous 2001 project have failed, with one suggestion being new drugs like statins have made it hard to repeat experiences precisely.

To put it another way, the scientific evidence remains distinctly muddled – even if Calder is eager to emphasise that the broad links between omega-3s to heart health “is still robust”. Nor is he alone in coming to a basically positive conclusion on decades of work. “It is important for individuals with cardiovascular disease (CVD) to have adequate omega-3 intake, either from foods or supplements, to improve cardiovascular health,” emphasises Simin Liu, a professor of epidemiology and medicine at Brown University. “New observational studies generally support the notion that a higher intake of fish reduces cardiovascular disease risks.”

At the same time, Liu describes a situation whereby popular conceptions about omega-3 sit awkwardly with the more cautious scientific findings. Cast your mind back to those ‘Heart Health’ pills and it’s easy to see what he means.

The research in a nutshell

While the academic consensus around omega-3 and how precisely it impacts the heart remains distant, exciting developments continue. Liu himself is at the centre of these developments, most recently contributing to a new paper in the Journal of the American College of Cardiology. The impressively comprehensive study included 884 intervention trials across 883,627 individuals, which Liu describes as “by far the most comprehensive” meta-analysis so far. The results, for their part, are equally striking. To quote the article directly, the scientists altogether found that omega-3 offered “moderate to high-quality evidence for reducing CVD risk factors”. Even better, omega-3 helped cut the mortality rate of people who did suffer CVD, as well as heart attacks and strokes.

However, while this latest bout of research is an optimistic step forward, it hardly closes the topic entirely. That’s obvious enough if you examine the details of Liu’s paper. Apart from studying omega-3, the team also explored the impact of a wide range of other nutrients. Encompassing everything from magnesium to zinc to melatonin, it’s clear that the heart is too complex a mechanism to be linked entirely to a single supplement – even one as powerful as omega-3s.

Calder agrees, as he puts it: “We know what a bad diet is, and we know what a good diet is. And we know that omega-3s aren’t the only difference between them.” From sugar to salt, Calder continues, a range of ingredients can theoretically impact an individual’s heart health. By the time you add other variables, like exercise and someone’s economic conditions, it can be hard to pinpoint exactly what omega-3 is doing – even if the consensus is it’s basically good.

There’s a similar question to do with consumption more specifically: how should you ingest omega-3s? This is far from a pointless question. After all, if someone is getting their fatty acids from salmon or sardines, their CVD risk might be reduced by a range of different minerals, or at least the way in which omega-3 and the others interact, rather than by omega-3 alone.

It’s precisely for that reason, indeed, that Calder is such a proponent of eating fish. “Personally,” he says, “I think eating fish is superior to taking supplements.” Liu, for his part, takes a slightly more emollient tone. “I see the two as complementary,” he argues. “It depends on the context and the individuals and populations targeted for interventions. For individuals with suboptimal diets or an older person who [could be] vulnerable to micronutrient deficiency, moderate micronutrient supplements may help to reduce the cardiovascular risk.”

The estimated global worth of the omega-3 industry by 2029.
Data Bridge Market Research

Something’s fishy about omega-3 Regardless of where you stand on the eternal debate of delivery method, it’s surely true that eating more fish would be good for you – both in terms of omega-3 and a host of other chemicals. Yet, with a few honourable exceptions, notably Japan and around the Mediterranean, the modern Western diet is depressingly lacking in seafood. As so often, the statistics are revealing here, with one 2019 survey finding only a third of UK consumers eat the recommended two portions of fish per week.

It’s a surprising statistic, notes Calder, given the UK is an island nation and historical figures as far back as Elizabeth I were concerned with eating too much fish. The solution, Calder suggests, involves a thoroughgoing transformation of how societies like Britain think about their natural bounty. That’s shadowed, he adds, by a re-evaluation of what supplements should be used for. He argues there’s a risk that, by relying on supposed miracle cures like omega-3, some may ignore other parts of their diet – with potentially fatal consequences for their hearts.

“We know what a bad diet is, and we know what a good diet is. And we know that omega- 3s aren’t the only difference between them.”
Professor Philip Calder

Not that the future necessarily involves a nation of anglers. As Liu warns, for all the clear benefits of fish, scientists must also thoroughly investigate the potential downsides of fish seafood, not least when it comes to the presence of mercury and other heavy metals.

If research continues to make a conclusive link between omega-3 and heart health, Calder is equally excited about the possibilities the nutrient could offer in other areas of medicine, especially in fighting cognitive diseases like dementia. That’s echoed, Calder continues, by increased interest around exploiting alternative sources of omega-3, particularly seaweed.

It seems clear, at any rate, that the fascination with these fatty acids will long continue – even if the question of heart health is finally put to bed.