Fish Oil and Depression, Mental Health

Essential Fatty Acid Supplementation May Affect Mood

BETHESDA, MARYLAND. Several studies have found a link between low cholesterol levels and an increased tendency to violence, suicide, and depression. Scientists at the National Institute on Alcohol Abuse and Alcoholism believe that the real culprit in this association is low concentrations of 5- hydroxyindoleacetic acid (5-HIAA) in the cerebrospinal fluid and that it is the blood level of polyunsaturated fatty acids rather than the levels of cholesterol which affect 5-HIAA levels. 5-HIAA is a metabolite of serotonin.

To test this hypothesis the researchers measured the levels of cerebrospinal 5-HIAA and the levels of blood plasma polyunsaturated fatty acids in a group of 176 subjects. Forty-nine of the subjects were healthy volunteers, 88 were early-onset alcoholics (excessive alcohol use prior to their 25th birthday), and 39 were late-onset alcoholics. None of the alcoholics had been drinking for at least 21 days prior to the test. The researchers found a strong positive correlation between blood levels of docosahexaenoic acid (DHA) and the level of 5-HIAA in the healthy volunteers. In other words, the higher the DHA levels the higher the 5-HIAA levels and as a corollary, the lower the tendency to depression, violence and suicide. In the early-onset alcoholics the situation was completely reversed. Higher DHA levels corresponded to lower 5-HIAA levels and thus a possibly increased tendency to violence, suicide and depression. The researchers found no correlation between 5-HIAA levels and total cholesterol levels. They conclude that further studies are required to determine if supplementation with essential fatty acids, notably DHA, which is found in fish oil supplements, can influence central nervous system serotonin and dopamine metabolism and modify impulsive behaviour related to these neurotransmitters.
Hibbeln, Joseph R., et al. Essential fatty acids predict metabolites of serotonin and dopamine in cerebrospinal fluid among healthy control subjects, and early- and late-onset alcoholics. Biological Psychiatry, Vol. 44, 1998, pp. 235-42

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