Fish Oil as Adjunct Treatment for Major Depressive Disorder

Inclusion Criteria:

1. Able to provide informed consent
2. Men or women aged 18-50 years
3. A primary psychiatric diagnosis of major depressive disorder (MDD), by Diagnostic and Statistical Manual-5th ed (DSM-5) using the MINI
4. HAMD total score≥21
5. No significantly modification of their diet from the time they sign consent to the end of study participation

Exclusion Criteria:

1. Suffering from other serious somatic diseases or comorbidities
2. Patients with serious nervous system disease
3. Patients in accordance with diagnostic standards of other mental illness
4. Patients who need to take benzodiazepine every day, and who currently need to be treated by electroconvulsive therapy or have received electroconvulsive therapy in the past 6 months
5. Pregnant women or lactating women, women with pregnancy plans during the trial period (12 months), women with a high risk of pregnancy but without taking any contraceptive measures
6. Patients with apparent suicide attempt or suicidal behavior
7. Any condition or medicines that may have an effect on biomarkers (within 1 week of the screening period or during whole trial period): long-term, regular use of NSAIDs, COX-2 inhibitors, immunosuppressant, steroids, interferon, chemotherapeutics, anticoagulants, malignancy, active autoimmune diseases, inflammatory bowel diseases, etc
8. Allergy history of PUFA
9. Intake of Fish oil more than 3g per day or eat fatty fish more than 3 times a week