Nutrition & Diet

Sugar Substitutes Activate Brain Reward Circuits Differently Than Sucrose

A randomized crossover study in 30 healthy adults used brain imaging to compare how sucrose and five low- or no-calorie sweeteners affect cerebral blood flow, gut response, and appetite. While most sweetener drinks behaved similarly to plain water in the brain, sucrose uniquely blunted activity in the ventral tegmental area — a key reward region — compared to water, sucralose, and monk fruit. Allulose combined with stevia delayed gastric emptying similarly to sucrose despite its low calorie count. Only sucrose raised blood glucose and insulin. The findings suggest that calorie-free sweeteners are not neurologically identical to sugar, particularly in reward pathways, which could have implications for appetite regulation and food behavior over time.