NEW YORK (Reuters Health) - New findings suggests that some people with depression might have problems metabolizing the B vitamin folate -- supporting the idea that supplements could help ward off the condition, researchers say.
Investigators in Norway found that depression occurred more commonly in people who had high levels of the amino acid homocysteine in their blood, and in those who carried a form of a gene that encodes a protein involved in processing folate.
Homocysteine is a normal byproduct of metabolism, and folic acid -- the form of folate found in supplements -- is known to aid in breaking down homocysteine.
"Lack of folate and/or a disturbed folate metabolism ... may partially be the cause of the depression in some people," study author Dr. Ingvar Bjelland of the University of Bergen told Reuters Health.
Previous research has suggested that folic acid supplements may boost the effects of antidepressants, an idea supported by the current study, Bjelland said.
The results, which appear in the Archives of General Psychiatry, "could even support the suggestion that folate may prevent depression," the researcher noted.
Bjelland and colleagues obtained their findings by scanning blood samples from 5,948 people between the ages of 46 and 49, and screening them for depression and anxiety.
The researchers found that people who had relatively high levels of homocysteine in their blood were almost twice as likely to be depressed, relative to people with the lowest blood levels of homocysteine.
According to the report, depression was also linked to a form of the gene for a folate-processing enzyme associated with poorer efficiency in the breakdown of folate.
Anxiety, however, was not related to either homocysteine or the folate-processing enzyme.
Although markers of folate metabolism appeared altered in depression, actual levels of folate in the blood did not appear to differ between people with and without depression.
Bjelland noted that while this result is surprising, measuring folate in the blood may, in fact, be a "less precise" indication of how much folate is actually in cells.
"In addition, in our study the laboratory method of measuring homocysteine was more accurate than the method for folate," Bjelland said.
Explaining why folate might play a role in depression, the researcher said the body may need the B vitamin to build important substances in the brain -- a lack of which may cause depression and other mental disorders.
To Bjelland, the current study supports a simple message: get your vitamins.
"Vitamins are important, not only for the physical health, but for the mental health as well," the researcher said.

SOURCE: Archives of General Psychiatry 2003;60:618-626.