Friday, March 19, 2010

Omega-3 update

Appleton et al. has published a recent review of evidence regarding the psychiatric effects of omega-3 supplementation.

Here's the link:

Basically, the conclusion is similar to my previous impression on this issue:  there is more evidence coming out, generally supporting the possibility that omega-3 supplementation can be modestly beneficial for treating depression.  But the existing evidence is somewhat shaky, heterogeneous, and probably influenced by publication bias.  

The authors overstate some of the conclusions: for example, they claim that, based on the evidence, omega-3 supplements are unlikely to be useful to prevent depression in a healthy population.  This is unfounded, since there were really no adequately long studies which aimed to show preventative effects.

Another of my usual complaints about the studies described is that they are of inadequate duration:  many lifestyle changes or treatments that could affect depression (an illness with a periodicity which is often over years or decades) may require several years of disciplined adherence before significant benefits would become apparent.  Most of the studies described were less than 3-6 months in duration. 

Another study by Amminger et al. from the February 2010 issue of Archives of General Psychiatry ( assessed subjects with signs of early psychotic disorder who were randomized to receive 4 capsules per day of fish oil (containing omega-3 fatty acids), or placebo daily, for 12 weeks.  In the following year, substantially fewer individuals in the fish oil group, compared to the placebo group,  went on to develop ongoing psychotic illness (5% vs. 28%).

I do encourage omega-3 supplementation, as it poses negligible risk, with a modest potential benefit, both with respect to mood and to some other areas of health.


Anonymous said...

Thank you for this entry Dr Kroeker.

I have been taking fish oil supplements on and off since last year.

I take 2 grams now every day, and the particular supplement I use has a 20:1 EPA:DHA ratio.

I asked my GP and he didn't know. He said take fish oil for your heart and it doesn't matter what ratio.

Do you have particular recommendation in terms of what ratio may be best for anxiety/depression?


GK said...

I don't think existing research answers this question definitively.

In one study--
--rats fed a diet with different amounts of DHA vs EPA benefited similarly in terms of lipids. But DHA-rich supplementation increased brain nitric acid synthase activity to a greater degree. Here, the EPA-rich diet actually had a ratio of only 1.5:1. The DHA-rich diet had a ratio of about 0.28:1. Most fish oils have ratios of about 1.5:1.

Here's a link to an article about DHA deficiency associated with neuropathology in affective disorders:

In this study, DHA alone was effective for depression (weak study design though):

In this better study, EPA alone was modestly effective for depression:
The above study, published in the Journal of Clinical Psychiatry, is worth reading.

My conclusion from the above, is that there is no particular reason to choose a particular ratio of EPA to DHA. Both are probably helpful for brain function. DHA in particular is particularly important. The easiest source of omega-3 supplementation is from fish oils with a 1.5:1 EPA:DHA ratio, so I see no need to stray from this, unless there are tolerability issues unique to you. I suspect that it would be more expensive to supplement with other ratios, as this would necessitate more processing.

Anonymous said...

yes, you're right Dr, it is more expensive to purchase fish oil with other ratios. This one cost me $60 for about 90 days supply and I very much regret having purchased it, specially given my financial situation. I've already opened it so I guess I have no choice but to consume it during the next few weeks. However, after that I will go with the typical ratio you mentioned given that there is no convergence in research studies and that DHA is important, as you note.

p.s. I found a passable online copy of the 2009 MGH study that you mentiond--for those interested:

Looks like the effect size was medium.

My only worry with fish oil is increased lipids in blood.

THank you for your wonderful blog and helpful replies.