17 May 1999

Fish may alleviate the symptoms of manic depression

As well as being delicious and nutritious a good meal of fish is fast gaining a reputation as a benefit to good health. Evidence for its effectiveness against a range of ailments, including heart disease and arthritis has been mounting for some time. And now, new research has claimed fish may also alleviate the symptoms of manic depression.

In research that has been described as a landmark study of how a naturally occurring dietary ingredient can affect the brain, it has been found that patients suffering from manic depression given capsules containing fish oil experienced a marked improvement over a four-month period.

"The magnitude of the effects were very strong. Fish oil blocked the abnormal signaling (in the brain) which we think is present in mania and depression,'' said researcher Andrew Stoll, the director of the pharmacology research laboratory at Harvard University's McLean Hospital.

The study, published in the American Medical Association's Archives of General Psychiatry, comprised 30 patients diagnosed with bipolar disorders, which are characterized by chronic bouts of mania and depression.

Roughly half the subjects received fish oil supplements and half got capsules containing olive oil, a placebo. They underwent psychological testing at two-week intervals during the four-month study. The chemicals in the fish oil believed to be at work on the subjects' brains were omega-3 fatty acids, which are present in certain types of fatty fish such as salmon and cod. They are also found in canola and flaxseed oil.

Among the many health benefits sometimes attributed to omega-3 fatty acids are smoothing blood flow through constricted arteries of heart disease patients, lubricating painful joints in rheumatoid arthritis sufferers, cutting women's risk of breast cancer, preventing an intestinal inflammation known as Crohn's disease, and even ridding the body of cellulite.

But there has been little done on the effect of omega-3 fatty acids on the human brain.

Stoll said omega-3 fatty acids boost levels of the neurotransmitter serotonin in the brain - similar to the effect of popular anti-depressants such as Prozac - although the mechanism by which either works remain uncertain.

He said previous research on animals showed that omega-3 fatty acids replenished the "lipid bilayer'' surrounding the body's cells, including brain cells, where receptors reside that receive signals from chemical transmitters.

Stoll theorized that diets in Western industrialized countries are low in fish and other foods containing omega-3 fatty acids, a deficiency that can be compensated for by consuming fish oil or flaxseed oil supplements.

Patients in the study received up to seven capsules daily with concentrated fish oil from menhaden, a type of Atlantic herring, containing a total of nearly 10 grams of fatty acids.

"If you're treating depression and bipolar disorder, you have to think of it as a medicine and take an adequate amount,'' Stoll said. He suggested that omega-3 fatty acids might be taken as an adjunct to anti-depressant drugs or lithium, which is commonly prescribed to treat bipolar disorders.