Difference in human brain activation between caloric sucrose and an artificial sweetener

Abstract

Recently, obesity has become a problem worldwide and has posed a significant health threat [Deneen and Liu 2011]. Although the causes of obesity are many, overconsumption of high-calorie foods is a major cause. Therefore, to prevent and overcome obesity, sugars are often substituted by artificial sweeteners for reducing caloric intake. However, whether artificial sweeteners can elicit human brain activation same as sucrose remains unclear. We investigated whether human brain activation by caloric sucrose differs from that by an artificial sweetener using functional MRI (fMRI). The Human Experimentation Committee of Kyushu University approved all experimental procedures. Seven males and 7 females (age, 22?33 years) participated in this study. Sucrose [24% (w/v)] and artificial sweetener (PalsweetTM) [8% (w/v)] solutions were used, and artificial saliva (25 mM KCl with 2.5 mM NaHCO３) was used as control. A taste solution and artificial saliva were alternately administered for 20 s, and the two tastes were delivered 12 times in a random permuted sequence. To evaluate the effect of each taste, [(sucrose)?(artificial sweetener)] and [(artificial sweetener)?(sucrose)] contrasts were performed using SPM8. An anatomical mask was applied on the statistical maps to retrieve activity data related to the taste pathway involving the thalamus, caudate, putamen, insula, amygdala, and anterior cingulate cortex (ACC). This analysis revealed that sucrose affected ACC, the insula, caudate, and putamen (P < 0.05 uncorrected) and that the artificial sweetener affected the thalamus, amygdala, insula, putamen, and caudate (P < 0.05 uncorrected). Sucrose but not the artificial sweetener elicited brain activation in ACC. ACC is implicated in reward-based decision making [Rogers RD et al. 2004] and is involved in guiding voluntary choices on the basis of the history of actions and outcomes [Kennerley S et al. 2006]. Taken together, sucrose may affect food consumption, and an artificial sweetener may not completely satisfy the desire for natural caloric sweet ingestion.