In part-four of my look at how omega-3 fatty acids influence depression, I’ll turn here to a flurry of evidence concerning how they may treat major depression and depressive symptoms in bipolar disorders.
I found nine double-blind controlled studies on how effective omega-3s can be for depressed patients, including those with bipolar disorder. Let’s take a look:
1999: A 16-week study of 30 bipolar patients used 6.2 grams (g) of eicosapentaenoic acid (EPA) plus 3.4 g of docosahexaenoic acid (DHA) — both are fish oil — and tested it versus placebo (olive oil). Patients were also taking antidepressants, benzodiazepines, or mood stabilizers. The omega-3 fatty acid group had a longer remission period than placebo group did. The omega-3 group did better than placebo group in all measures of depression.
2002: A one-month study looked at 20 patients with major depression. It compared 2.0 g of EPA to placebo (patients were also on antidepressants). Omega-3’s antidepressant effects were seen starting at week two. Omega-3 was superior to placebo for these symptoms: depressed mood, guilty feelings; feelings of worthlessness; and insomnia.
2002: A 12-week study looked at 36 depressed patients taking 1.0 g, 2.0 g or 4.0 g of EPA. They were also taking antidepressants. Those on the EPA 1.0-g dose did better than the placebo patients did in terms of their depression, sleep, anxiety, libido, and other factors. Those on 2.0 g or 4.0 g did no better than those taking placebo on these measures. The lower dose proved better.
2003: A six-week study of 35 patients with major depression compared 2.0 .g of DHA to placebo. It found that DHA did not actually have any beneficial impact over placebo.
2003: A two-month study of 22 patients with major depression compared 4.4 g of EPA and 2.2 g of DHA to placebo. Patients were taking antidepressants. The two fish oils combined resulted in significant reduction in depression scores over the placebo group. Omega-3 treatment was well tolerated, as well.
2005: A 12-week study of 77 patients with depression used 0.6 g of EPA and 2.4 g of DHA. Researchers found that omega-3 didn’t, in fact, differ from placebo in helping them.
2006: A 12-week study looked at 75 bipolar patients (type I or II). It used one g of EPA versus placebo. Patients were taking many different drugs. Omega-3, either 1.0 g or 2.0 g a day, was superior to placebo in its anti-depressive effects, as well as overall functioning over placebo treatment. EPA (1.0 g or 2.0 g a day) was well tolerated, but had no effect on mania.
2008: An eight-week study looked at 60 patients with major depression. The daily treatment was 1.0 g of EPA, 20 milligrams (mg) of fluoxetine (a common drug), or both omega-3 and the drug combined. It turns out that EPA had the same anti-depressive action as fluoxetine did, and combining the two led to better results than either treatment alone.
2008: A 12-week study looked at 190 patients with mild-to-moderate depression. Researchers used a mix of EPA and DHA, totaling 1.5 g a day, and compared it to placebo. The omega-3 combination didn’t show any beneficial effects over placebo on depressive symptoms.
Except for the two negative studies mentioned above, there is very promising evidence that omega-3 is effective either by itself or as an adjunctive treatment in both major depression and in preventing relapse of the depressive symptoms in bipolar disorder without serious side effects. However, future larger and better-designed studies are needed before omega-3 is routinely recommended in the prevention or treatment of depression.