ABSTRACT
Food ingredients (including food additives) have the potential to affect brain chemistry and function68 either by contributing molecules into existing neurochemical pathways, or by altering the levels of hormones that normally regulate brain chemistry. In order for a food constituent to affect the central nervous system it must necessarily be able to be absorbed from the gastrointestinal tract, enter the circulation and then elevate its plasma concentration above a 'normal' range. Then, it must have the ability to either cross the blood-brain barrier (due to its lipophilicity), or to serve as a ligand in one of the various blood-to-brain transport mechanisms.
