Omega-3 supplements: update

 A number of negative studies have come out in the past year or two, regarding various types of supplements.  

I think it is good to be wary of claims about supplements, just as we should be wary of biases related to pharmaceutical marketing or to therapists touting particular styles of psychotherapy.  

Here is a review of some recent research regarding omega-3 supplementation: 

A simple 12-week study by Fristad et al (2015), published in the Journal of Child and Adolescent Psychopharmacology, showed that omega-3 supplements, given over 12 weeks,  had a modest antidepressant effect in children with bipolar-spectrum symptoms.  The effect size was greater than placebo, but less than that of "psychoeducational psychotherapy." 

http://www.ncbi.nlm.nih.gov/pubmed/26682997

In a very recent meta-analysis by Cooper et al (2016), it is concluded that omega-3 supplements given to children with ADHD do not cause large symptom improvements.  But there is enough evidence, including from high-quality studies, to believe that omega-3 supplementation could lead to small improvements in emotional lability and oppositional behaviour. 
http://www.ncbi.nlm.nih.gov/pubmed/?term=10.1016%2Fj.jad.2015.09.053

Bos et al (2015) compared omega-3 supplements (650 mg/day EPA+DHA) with placebo, in a 16-week study of 79 boys with ADHD.  They found improved parent-rated attention scores in the omega-3 group.   The effects they report appear to be clinically significant.   http://www.ncbi.nlm.nih.gov/pubmed/25790022

Widenhorn-Muller et al (2014) showed an improvement in working memory in children with ADHD given 720 mg/day of omega-3 supplements for 16 weeks. 

http://www.ncbi.nlm.nih.gov/pubmed/?term=10.1016%2Fj.plefa.2014.04.004

In a JAMA article by Chew et al (2015), the authors show that omega-3 supplements, given daily over 5 years, do not slow down the rate of cognitive decline in elderly people.
 http://www.ncbi.nlm.nih.gov/pubmed/26305649

For a recent review, Mischoulon and Freeman's 2013 chapter in Psychiatric Clinics of North America is a good contribution.

Animal Studies
Gonzales et al (2015) showed that omega-3 supplements, given to rats, led to "increased adaptive coping with stressful events."

http://www.ncbi.nlm.nih.gov/pubmed/?term=10.1016%2Fj.bbr.2014.11.010

In this interesting article by Bondi et al, they suggest from their findings that omega-3 deficiency, continued over several generations, can cause "impairment in cognitive and motivated behaviour" in adolescent rats.  This may speak to the importance of the dietary quality through the entire lifespan, as a factor in psychological resilience.  The typical western diet is often described as progressively omega-3 deficient. 

http://www.ncbi.nlm.nih.gov/pubmed/?term=10.1016%2Fj.biopsych.2013.06.007

Conclusion

I continue to recommend omega-3 supplementation.  It is a reasonable supplement for those with symptoms of depression, ADHD, or bipolar disorder.   The dose to aim for is between 1 and 2 grams per day of EPA+DHA combined, usually with the EPA:DHA ratio at least 3:2.

I base this recommendation on the fact that there is reasonable evidence of a slight improvement, not only in measures of psychological health, but also in various other aspects of physical health (such as inflammatory diseases). 

I think the magnitude of any improvement due to omega-3 supplements is likely to be very slight.  But in combination with other factors, such as healthy lifestyle and responsible use of medication, it could be a component of balanced, holistic health care, particularly if continued regularly for long periods of time.  

One of the weaknesses of many of these studies is the lack of consideration for other lifestyle elements.   Considering diet alone, it is unlikely that omega-3 supplements would help very much if the rest of a person's diet is unhealthy.    A healthy, balanced, "Mediterranean" style diet, with lots of vegetables, healthy oils (such as olive), fish, and nuts, with minimal processed foods, minimal sugar, minimal simple carbs, is likely to be much more important in terms of nutritional care of mood, compared to any supplement alone.  However, omega-3 supplements could be a safe and possibly useful adjunct to an already healthy diet.