More Evidence That Fish Oil Supplements Might Be Useless

You most certainly know someone taking fish oil pills -- those fishy, translucent gold capsules -- for their purported heart benefits. But evidence continues to mount that fish oil might be snake oil. At the very least, it doesn't pack nearly the punch we once thought. Instead, it's probably just worth eating actual fish, which is loaded with plenty of healthy vitamins and minerals.

Image: Orange-Kun/Wikimedia Commons

A new study found taking fish oil supplements ineffective in preventing the surgically-produced blood vessel access points used for dialyses treatments from failing. This sounds niche, but unlike other fish oil studies we've reported on, blood vessels are the exact wheelhouse scientists thought taking fish oil supplements would make a difference in. The research highlights a continuing trend: Despite their popularity, fish oil pills and their so-called omega-3 fatty acids don't seem to be holding up to scrutiny.

"Based on the preponderance of evidence," wrote Gregory Curfman, editor in chief of Harvard Medical School's Harvard Health Letter for the Journal of the American Medical Association, "there is reason for scepticism that omega-3 fatty acid supplementation is effective" in preventing cardiovascular disease.

The latest study to reach that conclusion was simple. The researchers wanted to see if fish oil would prevent fistula failure -- failure of holes surgically created to access blood vessels that are clogging up. Fistula failure is one of the main causes of death in dialysis patients, who need their blood routinely filtered to remove waste, the scientists wrote in their paper published in this month's Journal of the American Medical Association. The team randomised 576 patients to receive either a placebo or fish oil for 12 weeks after receiving their fistula. Some patients also received aspirin, but it didn't matter. There was little difference between the groups in the number of failing fistulae.

So, what the hell is going on in the $US1.2 billion ($1.5 billion) fish oil industry? Last year, we reported that fish oil has been accumulating negative results -- only two of at least two dozen studies reported any benefit from fish oil supplements. Curfman explained that a pair of older trials from 10 and 20 years ago established fish oil's cardiovascular benefits but didn't include a placebo control. And the placebo effect, of seeing a benefit simply because the patient thinks there will be one, can be very powerful. Placebo-controlled trials since then have cast doubt on results of the first two studies.

I asked Alejandro Marangoni, lipid expert at the University of Guelph near Toronto, his thoughts on the matter. He was surprised by the results -- he expected to see a positive effect of fish oil supplements -- but pointed out one caveat. The oil in many of the fish oil pills could be oxidised, or spoiled. "If the health benefits are not there and on top of it all we are consuming a lot of rancid, oxidized oil, this could represent very negative health effects," wrote Marangoni in an email to Gizmodo.

So, what's next for you fish oil guzzlers? Scientists behind another clinical trial called VITAL, scheduled for completion in December 2017, are giving fish oil and vitamin D supplements to over 25,000 people in order to check whether the two, either separately or in tandem, reduce a person's likelihood of developing cancer and other diseases. Until then, Curfman still recommended trying to eat fish at least two to three times a week, on top of the standard recommendations: Exercise, eating healthily and not smoking.

[JAMA, JAMA]

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Comments

    Its weird, there is corrolation of what certain compounds like Omega 3 do in the body, not how they behave as a supplement/digestive/medicine.

    The gut biome and the blood have different interactions that are not accounted for or studied... how many years did it take to find out some dietary calciums were non digestible and passed through the body... or that Cassein naturally in small amounts found in milk in protein powder form can be metabolised in the blood into a pseudo morphine effecting the brain forming an addictive consumption... just to name a couple.

      Care to share a citation for "Milk is addictive"?

        Jumping in, a quick google search netted me this article on Casomorphin the metabolite product that can occur from digestion ofcasein in milk .

        I often find myself scratching my head over epidemiological studies linking such-and-such with something, as often there's little science beyond maths. In this example I've no clue whether the diet supplements used were even tested to determine whether these were actually fish oil or whether these were the more commonly available oil tablets that use vegetable carrier oils.. I'm pleased to see it's been mentioned too, as these unsaturated oils are prone to becoming rancid quite easily and I recall a study some time back that found many supplements did indeed contain rancid oils with potential for doing serious damage to the liver. This also led to the industry using additives like peppermint oil to mask detection of rancid oil.

        A major problem with science is once a study's been done it's rarely if ever revisited. I know a few researches who've been frustrated when they wanted to progress an area, submissions to re-evaluate or re-run preliminary research has been denied. basically - 'you don't need to confirm that, it's already been done'. Yet time and time again when eventually someone manages to get research re-run it's found the original study results cannot be repeated.. or as with the recent revelation about lowering cholesterol actually raising mortality rates, data is found that was excluded which shows the reverse of the original conclusion. There's little to no reviewing of p-hacks, only basic checking - and when reviewed it's found a huge number of papers have fundamental, flawed statistical methodology. Enough so to throw whole areas of research into doubt (European Project on OCean Acidification (EPOCA) did a review of OA studies in 2010 and found only 5% of studies were " judged to have appropriate experimental designs." but the kicker was this: "the number of experimental units used per treatment in studies was low (mean = 2.0)." .. really??? a sample size of TWO!?)

        The other issue researchers face and bemoan is studies that fail are never published. This has the potential to lead to repetitive wasted time as people run over the same old ground, or worse, p-hack to get a positive. In all, a large amount of research is flawed and requires constant review to detect the errors, and currently it can take decades to uncover the mistakes and even longer to bring about a change in thinking.

        Thanks Smiggle.

        My comment was in relation to it Leaky Gut Syndrome where infornation show bacteria, genetics or excessive consumption of certain foods can result in food not being digested into usable resources the body needs and instead creating toxic by products. (see wikipedia)

        I also think the ability to consume vitamins is genetic trait common to most humans, and defeciency in such traits would make supplements useless or toxic.

        Its weird how genetics and bacteria determine how we consume and absord material.. knowing Omega 3 (or anything) is good for the body doesnt mean consuming it will survive the trip into your body or be used by it, especially since everyone can react differently.

        Went off a tangent... The Milk addiction is a gut defeciency akin to how some people are lactose intolerant, and shows up varying degrees in population, so its rare-ish. but since it doesnt give people explosive diahhorea or vomiting it appears the least common diary problem. Its also funny they suspect many people who are lactose intolerant are also have the other defiecency cause they keep punishing themselves.

    To live in an age where rather than prove something works to believe it. We need to prove it doesn't work for people to stop believing.

      kudos. Spoken like a scientist :)

      Prove body uses it substance. Check

      Prove superfood contains it. Check...
      if not create supplements. Check.
      Prove the product is profitable. CASH or CHECK!!! :P

      Prove digestion of food/supplement delivers substance to the targetvlocation where its needed in body... NOPE. NEVER. Not profitable and usually takes a health educator study to counter

        The problem with your rational is super foods aren't actually real.

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