I've heard that taking fish oil tablets can help with depression. Is this true?
Omega-3 essential fatty acids are considered “essential” because they are not manufactured by the body and must be taken in as part of a diet. They are long-chain, polyunsaturated fatty acids. There is an optimal ratio of different fatty acids in one’s diet for proper enzymatic metabolism. For example, the typical American diet is high in omega-6 fatty acids, from cornflower, safflower, corn oils, etc., but omega-3 acids, from fish and plants tend to be underrepresented. The ratio of omega-3 to omega-6 fatty acids may be more important than the actual levels in the diet. The best-studied omega-3 fatty acids include eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), which are both found in marine animals such as fish.
Psychiatrists have been particularly interested in omega-3 fatty acids because they are “selectively concentrated in synaptic neuronal membranes and regulate vascular and immune functions that affect the central nervous system” (Freeman et al., 2006, p. 1954). Insufficient intake of omega-3 fatty acids may have psychiatric effects.
The American Heart Association recommends that adults eat fish twice a week and patients with coronary heart disease consume one gram of EPA and DHA combined each day (Freeman, 2009, p. 8). Based on this precedent, the American Psychiatric Association examined the evidence for a recommendation for psychiatric disorders and suggested that adults should consume fish at least two times a week, per the APA guidelines. Patients with a mood disorder should consume at least one gram of combined EPA and DHA (Ibid. p.9). While the APA has not taken any position on acupuncture for depression, its openness to nutritional supplementation is very progressive for such as conservative organization accustomed to scientism.
Epidemiologic data suggest that countries with lower fish consumption have 30- to 60-times higher prevalence of major depression, bipolar disorder, and post-partum depression than countries with greater fish consumption, such as Iceland and Japan (Freeman et al., 2006, p. 1955).
Su et al. conducted a double blind, placebo-controlled trial in 2003 with the combination of EPA and DHA (9.6 grams/day) and found significant decreases in HAM-D scores compared with placebo after eight weeks (p. 267). Peet and Horrobin conducted a randomized, placebo-controlled study that used one gram of EPA/day for 12 weeks in 2002. They found a 50 percent reduction in HAM-D scores and notable improvements in depressed mood, anxiety, sleep disturbance, libido, and suicidality (p. 919).
Appleton, Hayward, Gunnell, Peter, Rogers, and Kessler et al. looked at the effect of omega-3 fatty acids on depression in 18 randomized trials in 2006. They found “considerable heterogeneity” in the data and could not find much support for their thesis. They suggested larger trials to detect “clinically important benefits” (p. 1308).
Given the APA recommendation and the low risk in consuming omega-3 fatty acids, I recommend that your try this nutritional supplement.
Appleton, K.M., Hayward, R.C., Gunnell, D., Peters, T.J., Rogers, P.J. & Kessler, D. et al. (2006). Effects of N-3 long-chain polyunsaturated fatty acids on depressed mood: Systematic review of published trials. The American Journal of Clinical Nutrition, 84(6), 1308-16.
Freeman, M.P., Hibbeln, J.R., Wisner, M.D., Davis, J.M., Peet, M., Marangell, L.B., Lake, J., et al. (2006). Omega-3 fatty acids: evidence basis for treatment and future research in psychiatry. The Journal of Clinical Psychiatry, 67(12), 1954-67.
Su, K.P., Huang, S.Y., Chiu, C.C., et al. (2003). Omega-3 fatty acids in major depressive disorder. A preliminary double-blind, placebo-controlled trial. European Neuropsychopharmacology, 13(4), 267-71.
A lack of omega-3s has been shown to be associated with depression. Fish and fish oil capsules are primarily recommended because they are high in omega-3s.