Fish oil capsules are a popular choice for people keen to prevent heart attacks and cardiovascular disease – but do they work?
Auckland University's Dr Andrew Grey has compiled the best studies on fish oil from the world's most prestigious scientific journals which all use rigorous randomised controls.
He says there is no evidence to support any significant health benefit from fish oil capsules, but that is not stopping people from taking them.
An edited extract of the conversation:
Are [fish oil supplements] being recommended by clinicians or advocacy organisations, the likes of the Heart Foundation?
Some of them are. For example the American Heart Association – which is a very prominent advocacy group for heart health in the US – has had on its website since 2002 recommendations that individuals use fish oils for heart protection. It’s not a trival question in the sense that 10% to 15% of US adults take fish oils and the vast majority of them say they’re taking it for heart health.
What is the theory about why fish oil is a good thing to take?
It comes initially from population based studies looking at the diet of, in this case, Inuit people in North America who seem to have low rates of heart disease. An association was drawn between their oily fish intake and that low risk of heart disease. Then several other, what we call, observational studies which have the ability to test associations between dietary factors and health outcomes appear to support that hypothesis.
Are supplements themselves or is it more that they are concentrating on a piece of nutritional advice?
With fish oils the assumption was made that the active moiety in the whole fish, if there’s benefit from the whole fish, is the omega-3 fatty acids. The evidence that I’ve just discussed relates to omega-3 supplements.
There’s recently been a lot of discussion about nutritional guideline advice and the very low quality of evidence which is used to generate those often quite dogmatic guidelines.
Is there a difference in absorption of supplements compared to food consumption that you would draw attention to, as well?
What the clinical trial evidence we’ve analysed tells us is that if you take a supplement on top of whatever diet you’re taking it doesn’t seem to make any diffence to any aspect of your helath.