Study on Sugar-Sweetened Beverages and Insulin Sensitivity

US: There is a general belief 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 still in a debate.

Researchers from Yale University tested glucose tolerance and taste perception before and after participants consumed seven 355 mL novel-flavoured equi-sweet beverages over 2 weeks using randomized double-blind designs. They demonstrated 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 the midbrain, insular, and cingulate responses to sweet, but not sour, salty, or savoury, taste as assessed with fMRI. Taste perception was unaltered and consuming the carbohydrate alone had no effect.

Forty-five healthy humans were randomly assigned to consume:

• Beverages sweetened with sucralose (sweet uncoupled from calories – LCS)
• Beverages sweetened with sucrose (sweet coupled with calories – Sugar)
• Beverages sweetened with sucralose and combined with maltodextrin (Combo)

Oral glucose tolerance tests (OGTTs) (or single blood draws), sensory tests, and neuroimaging were conducted before and after participants consumed seven of their assigned beverages over 2 weeks in the laboratory. Protocol details and inclusion/exclusion criteria are listed in the STAR Methods. A parallel study was conducted in adolescents since adolescents go through a period of transient insulin resistance.

To surprise the researchers, the study result found that combining low-calorie sweeteners with other carbs and sugars caused insulin sensitivity to drop, which increases the risk of type 2 diabetes. Additionally, the researchers discovered that there were no changes in the brain or metabolic responses to sugars when drinks containing low-calorie sweeteners alone were consumed.

"The bottom line is that, at least in small quantities, individuals can safely drink a diet soda, but they shouldn't add French fries," states Professor Dana Small, director of the university's Modern Diet and Physiology Research Center and a senior author of the study.

Limitations of the study should be considered due to the small sample size and short duration. However, the findings provide an interesting avenue for further research to explore in-depth the effects of low-calorie sweeteners.

For more information, click on the following link: https://doi.org/10.1016/j.cmet.2020.01.014