A very interesting meta-analysis on what type of long chain Omega 3 – EPA or DHA, is most effective for treating depression. Why this is interesting is that many researchers have assumed that DHA is the most important long chain fatty acid for the brain because DHA is the primary structural component of brain tissue. In order to reduce depression however EPA is now been shown to be more important, probably due to it’s inflammatory effect. Inflammation is increasingly seen as a cause of depression as this review “A new paradigm for depression in new mothers..“notes:
The old paradigm described inflammation as simply one of many risk factors for depression. The new paradigm is based on more recent research that has indicated that physical and psychological stressors increase inflammation. These recent studies constitute an important shift in the depression paradigm: inflammation is not simply a risk factor; it is the risk factor that underlies all the others.
EPA is critical for reduction of inflammation as it the building block of anti-inflammatory eicosanoid hormones. This study notes: “EPA may improve depression via its anti-inflammation properties and the upregulation of Nerve Growth Factor.”
In today’s western diet we have a huge imbalance between our intake of Omega 3 and Omega 6 fatty acids. Omega 3 EPA and DHA are long chain fatty acids that are found in fish oil, either in supplements and oily fish like salmon and sardines. Most people are seriously deficient in omega 3, the average US diet contains just 150mg day, we should have at least 1000mg day. Omega 6 on the other hand is too abundant in our diets and we all need to make an effort to reduce it. Omega 6 found primarily in vegetable oils; sunflower, safflower, soybean etc. It is also higher in grain fed animals than grass fed. To avoid omega 6 use oils high in mono-unsaturated fat such as olive, avocado, macadamia and saturated fat like coconut oil, and eat grass fed animals and free range poultry.
As well as Omega 3 the review relating to pregnancy and depression notes there are other anti-inflammatory treatments for depression which can be useful:
In addition to omega-3s, several standard treatments for depression are also anti-inflammatory. For example, the herbal antidepressant St. John’s wort has long been known to be anti-inflammatory  . Traditional antidepressants are also anti-inflammatory and this may explain their efficacy. For example, a recent study compared C-reactive protein levels in cardiac patients with major depression before and after treatment with selective serotonin reuptake inhibitors (SSRIs). In these patients, C-reactive protein dropped significantly after treatment, independent of whether depression resolved  .
One could even argue that cognitive therapy is anti-inflammatory. Two recent studies have demonstrated that negative beliefs, such as hostility, can increase the levels of proinflammatory cytokines – especially IL-6 [74,75] . Cognitive therapy is a treatment for depression with known efficacy  . The primary goal of cognitive therapy is to reduce negative cognitions. Since negative cognitions increase inflammation, reducing their occurrence will have physical effects as well – primarily reducing inflammation.
“A new paradigm for depression in new mothers: the central role of inflammation and how breastfeeding and anti-inflammatory treatments protect maternal mental health”, Kathleen Kendall-Tackett International Breastfeeding Journal 2007, 2:6
(from Medscape, written by Kate Johnson)December 8, 2010 (Miami Beach, Florida)
Not all omega-3 fatty acids are equal when it comes to their antidepressant effects, according to a meta-analysis presented at the American College of Neuropsychopharmacology 49th Annual Meeting. In fact, only eicosapentaenoic acid (EPA) — and not docosahexaenoic acid (DHA) — is associated with mood improvement in patients with depression, concluded lead study author John M. Davis, MD, research professor at the University of Illinois in Chicago. The meta-analysis of 15 randomized, double-blind, placebo-controlled studies clarifies which type of omega-3 fatty acid is effective for depression and why previous findings on the antidepressant effects of omega-3 fatty acids have been contradictory, said Dr. Davis at a press conference. Omega-3 fatty acids are not synthesized by the body and therefore must be consumed in food (primarily fish and nuts) or supplements. In food, EPA and DHA are found together in a 1:1 ratio, but supplements can contain either fatty acid or a combination of both, he said. The study concluded that an EPA-predominant formulation is necessary for the full therapeutic antidepressant action, whereas the DHA-predominant formulation has little antidepressant efficacy. Modern diets may predispose individuals to omega-3 deficiency because changes in farming have resulted in a dietary increase in omega-6 fatty acids, which compete with omega-3 fatty acids in the body, said Dr. Davis. Although deficiency in omega-3 may predispose individuals to depression and supplementation may have antidepressant benefits, “omega-3 fatty acids are generally not euphoriants in that they do not help people whose mood is normal,” he said. A previous study by Dr. Davis and his colleagues looked at EPA intake among 8000 pregnant women participating in the Avon Longitudinal Study of Parents and Children and found that low intake was associated with high levels of depression (Epidemiology. 2009;20:598-603). Specifically, compared with women consuming more than 1.5 g of omega-3 from seafood per week, those consuming none were more likely to have high levels of depressive symptoms at 32 weeks’ gestation (adjusted odds ratio, 1.54). François Lespérance, MD, a professor of psychiatry at the Centre Hospitalier de l’Université de Montréal in Quebec, Canada, was the lead investigator on a recently published randomized controlled trial that found a benefit of omega-3 supplementation vs placebo in patients with major depressive disorder (J Clin Psychiatry. June 15, 2010 [Epub ahead of print]). Reached for comment on Dr. Davis’s study Dr. Lespérance said, “This meta-analysis provides additional evidence to what is already known through a limited number of studies in this field. It is therefore a useful summary of several clinical trials that most people may not know in detail.”
American College of Neuropsychopharmacology (ACNP) 49th Annual Meeting. Presented December 9, 2010.