FRIDAY, April 25 (HealthDay News) -- There's not enough scientific evidence to determine whether omega-3 fatty acid supplements can help treat people with bipolar disorder, say researchers at the University of Oxford in England.

People with bipolar disorder can shift between mania (elevated mood and energy) and depression. However, the use of omega-3 supplements to treat bipolar disorder is worthy of further study, since they seem to have no serious side effects, and many experts recommend them for people with heart disease and some immune disorders, said study authors Paul Montgomery and Alex Richardson.

They reviewed five studies that examined the use of omega-3 supplements for bipolar disorder, but only one study of 75 patients had enough data on results for Montgomery and Richardson to analyze.

Patients in that study had less severe depression symptoms while taking the supplements, but there was no change in their mania symptoms.

The review showed there's not enough scientific evidence to determine how omega-3s affect bipolar disorder, "and what evidence is currently available is of such a varied and oftentimes questionable nature that no reliable conclusions may be drawn," Montgomery said in a prepared statement.

The review was published in the current issue of the journal The Cochrane Library.

Some recent studies have suggested that omega-3s may be beneficial for other mood disorders such as depression, schizophrenia and personality disorders. It's not clear how omega-3s work in the body, but they may "play key roles in brain structure and function," Montgomery said.

Some of the studies considered for the review were funded by companies that make omega-3 supplements. Montgomery and Richardson have worked as consultants to several fatty acid supplement companies.

Patients with psychiatric disorders shouldn't take omega-3 supplements "in lieu of established psychiatric treatment options," said Dr. Joseph Hibbeln, head of the nutritional neurochemistry division of the National Institute of Alcohol Abuse and Alcoholism.

More information

The American Academy of Family Physicians has more about bipolar disorder.