Psychiatric disorders in general, and major depression and anxiety disorders in particular, account for a large burden of disability, morbidity and premature mortality worldwide. Omega-3 polyunsaturated fatty acids (PUFAs) have a range of neurobiological activities in modulation of neurotransmitters, anti-inflammation, anti-oxidation and neuroplasticity, which could contribute to psychotropic effects. 
Here the authors reviewed recent research on the benefits of omega-3 PUFA supplements in prevention against major depression, bipolar disorders, interferon-α-induced depression patients with chronic hepatitis C viral infection, and posttraumatic stress disorder.
The biological mechanisms underlying omega-3 PUFAs’ psychotropic effects are proposed and reviewed. Nutrition is a modifiable environmental factor that might be important in prevention medicine, which have been applied for many years in the secondary prevention of heart disease with omega-3 PUFAs.
This review extends the notion that nutrition in psychiatry is a modifiable environmental factor and calls for more researches on prospective clinical studies to justify the preventive application of omega-3 PUFAs in daily practice.