In a previous post which considered some of the bogus science claims made by the Australian TV show Today Tonight, I had a brief look at a few things that fish oil is supposed to treat. It seemed fair to say that counter to the strong claims made by TT, the evidence suggests that fish oil is not a good way to treat arthritis nor arrythmia. I also said that it didn’t seem to be a good treatment for depression.
A reader pointed out to me that in fact there was some evidence that Omega-3 fatty acids helped with depression. A number of reviews of the literature on the efficacy of fish oil on mood disorders (like this one, this one and this one) suggest that fish oil might help with depression. But, as each of the reviews point out, many of the studies are small and contain methodological problems. Almost all the reviews conclude that more research is needed to say anything conclusive about the efficacy of fish oil as a treatment for mood disorders.
Today, the ABC and Sydney Morning Herald carried stories about another study purporting to show that fish oil was a good treatment for mental illness. This time the claim is that when administered to children, it prevents the later onset of psychosis or schizophrenia. And while this study’s conclusions are very enthusiastic, it is very small with only 81 participants.
What should we conclude about all this?
The overwhelming conclusion is the boring old line: “more research is needed”. But we also know that there is mounting doubt about the efficacy of anti-depressants over placebos. It is increasingly looking like most of the reason why anti-depressants work is the hope that they provide patients. Moreover, unlike fish oil, antidepressants have significant adverse side-effects. So, given that fish-oil might chemically help with mood disorders, that it can provide hope (which is proven to help with depression) and that it has no significant side-effects, it seems like something that’s worth a try and certainly worth more research.
[Here's a link to a fascinating article in Newsweek about the dwindling evidence supporting the use of anti-depressants.]
[Here's the results of a search of PubMed for "omega-3" and "depression". Lots of studies, nothing very conclusive.]
Amminger, G., Schafer, M., Papageorgiou, K., Klier, C., Cotton, S., Harrigan, S., Mackinnon, A., McGorry, P., & Berger, G. (2010). Long-Chain Ω-3 Fatty Acids for Indicated Prevention of Psychotic Disorders: A Randomized, Placebo-Controlled Trial Archives of General Psychiatry, 67 (2), 146-154 DOI: 10.1001/archgenpsychiatry.2009.192
Might modify the statement about antidepressants and placebos by pointing out that the issue is with mild depression (as I’d expect any fish oil studies might be). That antidepressants can be effective for major depression is not controversial.
There’s also the question of whether fish oil would be as effective a placebo as anti-depressants, ie. people might be less likely to believe fish oil will work as opposed to anti-depressants?
Yeah – that’s certainly a consideration. But I recall seeing somewhere that nearly 80% of patients in placebo studies guess correctly whether they are on the real drug or the placebo. So it’s an interesting question how *much* hope you need for the placebo effect to be significant.
There’s no doubt that some anti-depressants can alter brain chemistry. For some individuals where a chemical imbalance is the cause there may be a place for anti-depressant and anti-psychotic medications. Individuals should have an omega 3 screening done to investigate if there is a need for supplementation of omega 3′s through the use of fish oils. These subgroups of patients may respond positively to adding fish oils to their diet. Of course, there is also the problem of determining the appropriate dose that would bring their omega 3 levels to a more normal level.