The influence of flavour enhancers such as monosodium glutamate (MSG) on satiation and satiety is unclear, and
the present study aimed to explore this by examining the effects consumption of soups varying in MSG (1% MSG
added or no MSG) and macronutrient content (added carbohydrate, protein or control) had on appetite. 24
non-obese, low-restraint male participants consumed a fixed portion of soup and rated their appetite before,
immediately after intake and at 15 minute intervals for 120 min post-ingestion across six sessions. Added
MSG significantly increased flavour pleasantness and tended to result in a smaller decrease in hunger immediately
after soup ingestion. MSG also reduced rather than enhanced feelings of fullness immediately after ingestion
of the high protein soup. As expected, hunger increased, and fullness decreased, over the subsequent
120 min, but the increase in hunger was significantly lower in the MSG than no-MSG conditions with the protein
soup between 30 and 60 min post-ingestion. Overall these data suggest that MSG may have a bi-phasic effect on
appetite, with reduced satiation mediated by effects on palatability, but potential for enhanced post-ingestive
satiety particularly in the context of protein ingestion.