Despite its promise of helping to protect our hearts and minds, fish oil’s reputation has taken some hits lately. Omega-3 supplements don’t appear to improve cognitive function in older people, reported one study last year, while another review looking at prevention of heart disease and stroke concluded that fish oil wasn’t much help there, either.
But it’s not time to write off fish oil yet – at least not when it comes to mental health, says Professor Gordon Parker, Scientia Professor at the School of Psychiatry at the University of New South Wales.
"Even though research into fish oil’s effects on depression has had mixed results, it’s an evolving story," says Parker who believes the reason for conflicting findings may be that different formulations of fish oil supplements have different effects.
"We still need to work out which formulation is best for depression and at what dose," he says.
Fish oil contains omega 3 fats with names so eye-glazing that they’re best known by their initials. There’s EPA (eicosapentanoic acid) and DHA (docosahexaenoic acid) both of which help regulate the brain chemicals that affect our mood and cool the inflammation thought to contribute to depression, arthritis, heart disease and dementia.
To get enough of these fats we need fish – two to three serves of oily fish like sardines, salmon, trout or mackerel weekly delivers the daily 500mg of omega-3 fat recommended by the Heart Foundation. Although we can make some of these fats ourselves by eating plant foods like flaxseed, chia seeds and walnuts which contain another omega-3 fat - ALA, short for alpha linolenic acid - we only produce a small amount.
For improving depression, fish oil supplements containing more EPA than DHA appear to be the most effective, but more studies are needed says Parker, the former director of the Black Dog Institute, which specialises in treating and researching mood disorders. Although finding the optimal dose for depression is a work in progress, the Institute generally recommends two 500mg capsules daily.
"Fish oil may also help protect young people from serious mental illness – an Australian study of adolescents at risk of schizophrenia found that those taking fish oil supplements had a much lower risk of developing psychosis," he adds. "Although the general advice is two to three serves of oily fish each week, for adolescents and young people with an increased risk of psychosis or mood disorder, there’s an argument for taking three or four capsules daily of a fish oil supplement containing 180mg of EPA and 120mg of DHA."
Parker is working on a study* to see if fish oil helps women with bipolar disorder keep their moods stable during pregnancy. Pregnant women with bipolar are between a rock and a hard place – using mood stabilising drugs is linked to an increased risk of pregnancy complications, but avoiding medication can seriously affect their mental health.
"We know that omega 3 supplements are safe in pregnancy and that they can help with depression in bipolar disorder when they’re used in conjunction with medication – now we want to find out if omega-3 supplements alone can keep moods stable in pregnancy," says Parker.
Differences in the quality of fish oil supplements and the use of different doses can also explain mixed results in studies on cardiovascular disease, says Dr Rob Grenfell, the Heart Foundation’s Director of Cardiovascular Health.
"There’s a lot more to learn about fish oil, but research so far suggests it helps keep blood vessels healthy and reduces the risk of clots by helping thin the blood. It’s a long term benefit that comes from taking it consistently which is why we recommend sticking with oily fish three times a week,” he says. "If you can’t eat fish for some reason, ask your doctor about supplements."
Still, you can't have a conversation about eating fish without thinking about the sustainability issue. For information about shopping for sustainable seafood, see Australia's Sustainable Seafood Guide from the Australian Marine Conservation Society.
*Women who have bipolar disorder and are pregnant (less than 10 weeks) are invited to participate in this study which is recruiting both women who’ve decided to maintaintheir mood stabiliser medication andwomen who have decided to discontinue it and take fish oil. For more information, contact Amelia: firstname.lastname@example.org or (02) 9382 9268.