There is a general consensus that overconsumption of sugar-sweetened beverages contributes to the prevalence of obesity and related comorbidities such as type 2 diabetes (T2D). Whether a similar relationship exists for no- or low-calorie “diet” drinks is a subject of intensive debate and controversy. Here, we demonstrate that consuming seven sucralose-sweetened beverages with, but not without, a carbohydrate over 10 days decreases insulin sensitivity in healthy human participants, an effect that correlates with reductions in midbrain, insular, and cingulate responses to sweet, but not sour, salty, or savory, taste as assessed with fMRI. Taste perception was unaltered and consuming the carbohydrate alone had no effect. These findings indicate that consumption of sucralose in the presence of a carbohydrate rapidly impairs glucose metabolism and results in longer-term decreases in brain, but not perceptual sensitivity to sweet taste, suggesting dysregulation of gut-brain control of glucose metabolism.
The study by Dalenberg et al. found that sucralose consumption does not alter sweet taste perception nor affects glucose metabolism or insulin sensitivity when consumed alone, but suggested that co-ingesting sucralose with a carbohydrate impairs glucose metabolism in healthy humans. This finding was rejected in a later study by Khan and Sievenpiper who re-analysed some of the original data to address methodological considerations in Dalenberg et al. study design.
Dalenberg et al. assessed taste perception and glucose tolerance before and after participants consumed seven 355 mL equi-sweet beverages over 2 weeks in a parallel study design. These beverages were sweetened with either sucralose (0 Kcal) or equi-sweet sucrose (120 Kcal), or a control beverage containing the same dose of sucralose plus the non-sweet carbohydrate maltodextrin (120 Kcal).
The results reported that in healthy human adults, reduced insulin sensitivity and blunted brain response to sucrose were observed following 2-week consumption of beverages containing a combination of sucralose and maltodextrin (n=13), whereas no changes were observed following equal consumption of beverages with sucralose alone (n=13), sucrose (n=13), or maltodextrin (n=15; separate analysis at a later time). This latter analysis was criticised and re-conducted by Khan and Sievenpiper, who concluded that the effect of the combination of sucralose with a carbohydrate on glucose metabolism was very likely mediated by maltodextrin and not by the sweetener itself.
A summary of the study by Khan and Sievenpiper is available by clicking here.
An ISA statement in response to the study by Dalenberg et al is available on the ISA website by clicking here.