Chemical malfunction plays role in bulimia, researchers say

February 14, 1999
Web posted at: 9:49 p.m. EST (0249 GMT)

CHICAGO (AP) -- A new study adds to evidence that the eating disorder bulimia springs at least in part from a chemical malfunction in the brain and not merely from excessive desire to remain thin, researchers say.

In the study released Sunday, women who had suffered from bulimia and recovered were more affected psychologically than other women by being deprived of tryptophan, which plays an indirect role in appetite regulation, researchers found.

Tryptophan is an amino acid that occurs naturally in many foods and is used by the body to make serotonin, a mood- and appetite-regulating chemical in the brain.

Compared with normal women, the recovered bulimics reported bigger dips in mood, greater worries about body image and more fear of losing control of eating after being deprived of dietary tryptophan for about 17 hours, researchers said.

The study, published in the February issue of the American Medical Association's Archives of General Psychiatry, involved 10 recovered bulimics and 12 normal women.

Subjects were given identical-looking fruit drinks and snacks in the study, some with tryptophan and some without. They were not told which was which.

"These findings suggest that lowered brain serotonin function can trigger some of the clinical features of bulimia nervosa in individuals vulnerable to the disorder," said researchers led by Katharine A. Smith of the University of Oxford, England.

An expert not involved in the study said it adds to growing evidence that bulimia, a disorder in which sufferers typically alternate between binge eating and starving or purging, is biologically rooted and seems to have something to do with the system's inability to regulate serotonin.

Dr. Walter H. Kaye of the University of Pittsburgh said he and his colleagues last year reported finding abnormal levels of a serotonin-related chemical in the spinal fluid of actively bulimic women.

"What this (new study) is saying ... is these disturbances persist after people recover -- and more likely are there before people develop the disorder -- and these may be the kind of vulnerabilities that create eating disorders in the first place," Kaye said.

The Associated Press contributed to this report.