Carbohydrate craving, obesity and brain serotonin

Area of Science:

• Neuroscience
• Nutritional Science
• Behavioral Science

Background:

• The brain monitors dietary composition through plasma amino acid patterns, particularly the plasma tryptophan ratio.
• Food intake alters plasma amino acid levels, affecting tryptophan transport into the brain and subsequent serotonin synthesis.

Purpose of the Study:

• To review evidence that the brain uses food-induced serotonin changes to regulate subsequent food choices.
• To discuss the role of this mechanism in obesity-related carbohydrate craving.

Main Methods:

• Review of existing research on diet-induced changes in plasma amino acids and brain serotonin.
• Analysis of studies on food choices in hospitalized subjects with varying macronutrient ratios.
• Examination of the effects of D-Fenfluramine on carbohydrate craving.

Main Results:

• Carbohydrate-rich meals increase brain tryptophan and serotonin, while protein-rich meals decrease them.
• Brain serotonin levels appear to influence food selection for the next meal.
• D-Fenfluramine, a serotonin enhancer, reduces carbohydrate craving in subjects.

Conclusions:

• The brain utilizes serotonin signaling influenced by diet to guide eating behavior.
• Disruptions in this serotonin-mediated mechanism may underlie carbohydrate craving associated with obesity.