Figure 3.

Improperly balanced amino acid precursor administration leads to depletion of the nondominant system causing a relative nutritional deficiency of that system through competitive inhibition at the L-aromatic amino acid decarboxylase by the dominant system during synthesis of serotonin and dopamine.

Abbreviations: 5-HTP, 5-hydroxytryptophan; L-dopa, L-3,4-dihydroxyphenylalanine.