The brain is one of the organs in the body with the highest level of lipids (fats). Omega-3 fatty acids are important components of nerve cell membranes. DHA, in particular, is involved in various nerve cell processes. Omega-3 fatty acids from fatty fish in the human diet may be effective in the prevention of stress and other disease conditions including depression, and dementia.


In a review of evidence of omega-3 fatty acid in depression, four of seven trials showed significant improvement of depression with at least 1 g/day of EPA. Results from a trial have also shown therapeutic benefits with omega-3 fatty acids in depression during pregnancy. In a Finnish study, the risk of depression and suicidality was much lower in those who frequently ate fish.

Bipolar Disorder

Scientists in Taiwan compared omega-3 supplementation (10 capsules per day, each containing EPA 440 mg and DHA 220 mg) with usual treatment in patients diagnosed with a major depressive disorder for a duration of eight weeks and concluded that omega-3 PUFAs could improve the short-term course of illness. Patients on omega-3 supplementation experienced a significantly greater decrease in the Hamilton Depression Scale score than did those in the control group. In another clinical study of 30 people with bipolar disorder, omega-3 fatty acids (EPA and DHA 9.6 g/day) in addition to usual treatment for four months could maintain mood stability; also, patients experienced fewer mood swings and recurrence of either depression or mania than those who received a controlled drug.


Preliminary clinical evidence suggests that people with schizophrenia experience an improvement in symptoms when given omega-3 fatty acids. Omega-3 fatty acids reduce the antipsychotic drug requirement in first episode patients with schizophrenia and may be an effective adjunct to antipsychotics. But, a recent study observed no additional benefits of EPA supplements than placebo in improving symptoms of schizophrenia.

Attention Deficit/Hyperactivity Disorder

Children with attention-deficit/hyperactivity disorder (ADHD) may have low levels of EFAs including EPA and DHA. In a clinical study of about 100 boys, learning and behavioral problems (such as temper tantrums and sleep disturbances) were more common in boys with lower omega-3 fatty acid levels than those with normal omega-3 fatty acid levels.


A child diagnosed with autism who received 540 mg of the omega-3 fatty acid daily in the form of EPA for four weeks experienced a complete end to his previous anxiety about everyday events as reported by his parents and clinician. His overall quality-of-life was also improved. In another trial, most parents of 18 children with autism who had been given fish oil supplements for six months described improvements in overall health, cognition, sleep patterns, social interactions and eye contact. A recent trial reported reduced hyperactivity and reduced stereotypy (repeated movements like hand-flapping) in children who received 1.5 g of fish oil per day, as compared to children who received placebo.

Eating Disorders

Omega-3 fatty acids have also been researched in eating disorders such as anorexia nervosa. In a pilot study of EPA supplementation in the treatment of anorexia nervosa in seven young patients, three recovered and four improved.


Omega-3 fatty acid supplementation may have an inverse relationship with the risk of dementia and cognitive decline. People who have diets rich in fish would have a significantly lower risk of dementia and Alzheimer’s disease. Omega-3 fatty acid supplements may slow cognitive decline in some patients with very mild Alzheimer’s disease, though they do not appear to affect those with more advanced cases. A study by researchers at Tufts University in Boston found that people with the highest blood levels of DHA had a 47% lower risk of developing dementia and a 39% lower risk of developing Alzheimer’s. The study analyzed the blood of 899 men and women with an average age of 76. All participants were free of dementia at the beginning of the study, and underwent neuropsychological testing after giving their initial blood sample. In patients with mild cognitive impairment, a significant improvement in the cognitive portion of the Alzheimer’s Disease Assessment Scale (ADAS-cog) was noted.