Omega-3 fatty acids are found primarily in fish oil
and certain marine algae. Because depression appears less common in nations
where people eat large amounts of fish, scientists have investigated whether fish oils may
prevent and/or treat depression and other mood disorders. Two omega-3 fatty
acids — eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) — are
thought to have the most potential to benefit people with mood disorders.
How might omega-3s improve depression?
Different mechanisms of action have been proposed.
For example, omega-3s can easily travel through the brain cell membrane and
interact with mood-related molecules inside the brain. They also have
anti-inflammatory actions that may help relieve depression.
More than 30 clinical trials have tested different omega-3 preparations in people with depression. Most studies have used omega-3s as add-on therapy for people who are taking prescription antidepressants with limited or no benefit. Fewer studies have examined omega-3 therapy alone. Clinical trials typically use EPA alone or a combination of EPA plus DHA, at doses from 0.5 to 1 gram per day to 6 to 10 grams per day. To give some perspective, 1 gram per day would correspond to eating three salmon meals per week.
Meta-analyses (research that combines and analyzes
results of multiple studies) generally suggest that the omega-3s are effective,
but the findings are not unanimous because of variability between doses, ratios
of EPA to DHA, and other study design issues. The most effective preparations
appear to have at least 60% EPA relative to DHA. While DHA is thought to be less
effective as an antidepressant, it may have protective effects against suicide.
Recent work at Massachusetts General Hospital and
Emory University suggests that depressed individuals who are overweight and
have elevated inflammatory activity may be particularly good candidates for EPA
treatment.
Children and
adolescents with depression may also benefit from omega-3 supplementation. At
Harvard, there is a large study underway examining whether omega-3 supplementation
(alone or in combination with vitamin D) can prevent depression in healthy
older adults.
Omega-3s for other mental health conditions
Omega-3s have been studied in various mood
disorders, such as postpartum depression, with some promising results. In
bipolar disorder (manic depression), omega-3s may be most effective for the
depressed phase rather than the manic phase of the illness. The omega-3s have
also been proposed to alleviate or prevent other psychiatric conditions
including schizophrenia, borderline personality disorder, obsessive-compulsive
disorder, and attention deficit disorder. However, there is still not enough
evidence to recommend omega-3s in these conditions.
What dose of omega-3s is beneficial?
Doses for depression range from less than 1 g/day
to 10 g/day, but most studies use doses between 1 and 2 g/day. In my practice,
I recommend 1 to 2 g/day of an EPA+DHA combination, with at least 60% EPA, for
major depression. I am more cautious in patients with bipolar depression,
because the omega-3s may bring on mania, as can most antidepressants. In these
individuals, I recommend using omega-3 cautiously, and preferably in
combination with a prescription mood stabilizer.
Side effects and other safety considerations
Omega-3s are generally safe and well tolerated.
Stomach upset and “fishy taste” have been the most common complaints, but they
are less frequent now thanks to manufacturing methods that reduce impurities.
Past concerns about omega-3s increasing the risk of bleeding have been largely
disproven, but caution is still advised in people taking blood thinners or who
are about to undergo surgery.
As mentioned, caution is needed in people with
bipolar disorder to prevent cycling to mania. Because omega-3s are important to
brain development, and pregnancy depletes omega-3 in expectant mothers,
supplementation should theoretically benefit pregnant women and their children.
Fish consumption in pregnancy is supported by the FDA, but because we do not
have long-term data on the safety or optimal dosing of omega-3s in pregnancy,
expectant mothers should consider omega-3 supplements judiciously.
The bottom line on omega-3s and mental health
Omega-3 fatty acids are promising natural treatments for mood disorders, but we need more research about how they work, how effective they really are, and their long-term safety before we can make conclusive recommendations for people managing mental health conditions or who wish to improve mood.
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