A Low Protein, High Carbohydrate Diet Attenuates Alcohol Intake in Rats

To test whether a tryptophan-enhancing diet will reduce alcohol intake as serotonergic drugs do, two studies were conducted. In Experiment 1, 32 male, alcohol-drinking rats were randomly assigned to one of four isocaloric diets containing 25%-protein/65%-carbohydrate, 25%-protein/4%-carbohydrate, 4%-protein/65%-carbohydrate, or 4%-protein/4%-carbohydrate. Following a baseline week during which they ate standard lab chow, rats were offered their assigned experimental diet, water, and 5%-alcohol solution ad lib for three weeks. Alcohol and diet intakes were measured daily. In Experiment 2, 32 naive male, alcohol-drinking rats were assigned to one of the experimental diets used in Experiment 1. Following a one-week baseline, rats were offered their assigned diet, water, and 5%-alcohol/1%-sucrose solution ad lib for two weeks and then were switched back to standard lab chow for one week, with alcohol intake measured daily. Rats consuming the low protein, high carbohydrate diet drank 60-80% less alcohol than did rats offered other diets. This reduction in alcohol intake is most likely due to increased brain serotonin levels produced by the dietary manipulation.