Omega-3: The treatment in search of an illness makes a comeback

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Chances are you or someone you know, at some point, has popped a few of those honey-yellow gel capsules containing omega-3 fatty acids — likely in the name of good heart health.

The nutritional benefits of eating fatty fish — such as salmon, mackerel or tuna — have long been known. And there are entire generations of people who have fond memories of downing spoonfuls of cod liver oil.

That faith in fish oils has certainly been healthy for the bottom line of producers of omega-3 supplements — a global market valued at $3 billion.

And the scientific study of the benefits of omega-3 supplements also seems like an industry in itself, with more than 3,000 clinical trials alone registered at the esteemed Cochrane Library, a collection of medical and health-care databases.

This body of research tests hypotheses that the anti-inflammatory benefits of omega-3 could be used to treat or prevent an incredibly wide range of conditions, including ADHD, breast cancer, heart disease, high cholesterol, HIV, diabetes (Types 1 and 2), Tourette's syndrome, suicide and mania.

But when teams of researchers scrutinize the most reliable of these studies and put them together — known as meta-analyses — they conclude the treatment potential of these supplements is minimal to nil. Or, in a few cases, inconclusive.

(Reducing the risk of preterm births is perhaps the exception.)

But the 10 per cent of Canadian adults who take an omega-3 supplement might feel some vindication after a new review of all these meta-analyses concludes omega-3 can further reduce the symptoms of depression when taken in conjunction with antidepressants.

'Wasting money' on supplements

This "meta-analysis of meta-analyses" of randomized controlled trials — published in the journal World Psychiatry — examined the efficacy of the most popular and promising nutritional supplements, such as vitamins B, D, E, zinc, omega-3, probiotics and magnesium.

All of these are supplements targeted in a scathing 2013 editorial published by high-profile medical researchers in the Annals of Internal Medicine, titled Enough Is Enough: Stop Wasting Money on Vitamin and Mineral Supplements.

And it's likely no surprise that most supplements didn't fare as well as omega-3, which had "the most consistent evidence we found across all the different supplements," said study co-author Brendon Stubbs, of King's College London.

But how did Stubbs and his colleagues find a new treatment potential for omega-3, when past reviews didn't?

"There's rapidly growing interest in the field … so the evidence is constantly evolving," said Stubbs, adding that his team reviewed the most up-to-date studies in the field.

But he also noted more research is needed to determine what exactly is at play when it comes to omega-3.

The last five years have seen a resurgence of interest in fish oils, largely in a specific fatty acid found in omega-3 — eicosapentaenoic acid (EPA). University of Toronto nutrition sciences professor Richard Bazinet said this latest review has validated that emerging literature.

"When they separated the studies out by the ones that use mostly EPA, they are the ones that seem to be showing promise or are working," he said. "That's what the study is reconfirming."

EPA's most exciting development came in January, when a five-year study published in the New England Journal of Medicine found that heart patients who were taking a prescription form of EPA, along with their other medications, lowered their risk of a cardiovascular event, such as heart attack or stroke.

The manufacturers of omega-3 supplements were more than just cheering from the sidelines; they used the findings to promote their own products.

'War' over omega-3

"It created a bit of a war because a lot of the supplement companies said, 'Hey, look what EPA does. Our product has EPA.' And the drug company turned around said 'No, no, no. We're a drug. We're FDA approved. You can't use our research to support your product,'" said Bazinet.

The pharmaceutical company which produced the EPA-derived drug, Amarin, had a point. Its product wasn't straight-up EPA from omega-3 supplements that could be bought from your local store: it was a concentrated derivative of EPA.

Amarin took two supplement-makers to court and eventually settled.

So that's the catch, so to speak, with fish oils. It's likely these pure forms of EPA that are the future of omega-3 research, Bazinet said, and not necessarily over-the-counter supplements.

It's also worth noting that any benefit demonstrated by EPA — be it cardiovascular or psychological — has only happened when it's taken alongside conventional pharmaceutical drugs.

Still, omega-3 isn't likely to win over physicians who often find themselves deprescribing supplements for their patients.

Dr. Samir Sinha, a Toronto geriatrician, said omega-3 is one of the most popular supplements he's regularly telling his elderly patients they can stop taking.

"When I tell them these haven't been shown to be helpful, a lot of patients thank me,'' Sinha said. "Because I say, 'By getting rid of all of these things, I've just saved you a bucket-load of money.'"

As for Bazinet, whose own nutrition research examines aspects of fish oils' effects on the brain, he also doesn't bother with omega-3 supplements, preferring to get his intake straight from the source.

"I happen to walk by a fish shop every night on the way home," he said. "[Sometimes] I enjoy a nice fish meal."

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