A drop in serotonin levels in the brain may trigger the symptoms of the eating disorder bulimia nervosa in susceptible individuals. Indeed, healthy women who diet may experience a drop in brain serotonin levels, a step that may set up the cycle of bingeing and purging in people susceptible to bulimia. This maneuver produces a rapid lowering of plasma tryptophan with a consequent decrease in brain tryptophan and brain serotonin synthesis. Those women who had recovered from bulimia were more likely than other women to feel fat and fear losing control of eating in the 7 hours after being given the tryptophan-free mixture, the researchers report.

These findings suggest that lowered brain serotonin function can trigger some of the clinical features of bulimia nervosa in individuals vulnerable to the disorder. It is also possible that depression plays a role, given that all the former bulimics in the study had also been diagnosed with major depression. Moderate dieting is known to lower blood levels of tryptophan, which may alter serotonin levels in the brain. Therefore, this may be one way in which dieting may trigger bulimia in individuals who, by virtue of their genetic endowment and personal experience, are at particular risk for developing the disorder.

Archives of General Psychiatry February 1999;56:171-176.

COMMENT: Using L-tryptophan in this situation would certainly seem appropriate. Despite what your local pharmacist may tell you, tryptophan has been available with a prescription for the last two years. Liquid zinc may also be another helpful adjunctive treatment here. There are a number of good reports indicating excellent results with this treatment.