Consuming sucralose-sweetened beverages with carbohydrates may impair insulin sensitivity, according to a study recently published in Cell Metabolism.
Researchers led by Dana M. Small, PhD, director of the Modern Diet and Physiology Research Center at Yale University in New Haven, Conn., point out that there is still significant controversy surrounding the effects of no- or low-calorie sweeteners (LCSs) on human health. These sweeteners have been positively associated with weight gain and weight loss, with diabetes, and with lower BMI, or they’ve been found to be unrelated to metabolic health. “A similar inconsistency exists in the animal literature, with three recent reviews reaching three different and mutually exclusive conclusions. Given the growing use of LCSs, especially in relation to the obesity and diabetes pandemics, it is of pressing importance to resolve the controversy surrounding LCS consumption,” the authors write.
Small and her team write that several mechanisms have been proposed to resolve this controversy, including uncoupling sweet taste from energy receipt, which could lead to weakening conditioned responses to sweet taste. “Support for this uncoupling hypothesis comes from a series of studies in rodents reporting weight gain or glucose intolerance in rats consuming yogurts sweetened inconsistently with sucrose and LCSs compared to rats consuming yogurts consistently sweetened with only sucrose,” the authors write.
For this study, the researchers wanted to test the sweet uncoupling hypothesis in humans. They enrolled 45 participants aged 20 – 45 who don’t typically consume LCSs and had them consume seven 355 mL novel-flavored beverages over two weeks. The sweeteners were consumed as fruit-flavored beverages with added sucralose, with table sugar, or with maltodextrin added to their sucralose drinks as a control group. (The researchers chose maltodextrin, a non-sweet carbohydrate, to control for the calories of sugar without adding more sweet taste to the beverage.) The investigators conducted studies on the participants before, during, and after the testing period, including performing fMRI scans to look at changes in the brain in response to sweet tastes, as well as other tastes like salty and sour. They also measured taste perception and did an oral glucose tolerance test to look at insulin sensitivity.
Surprisingly, it was this control group that showed changes in the brain’s response to sweet taste and the body’s insulin sensitivity and glucose metabolism. Small and her team then added a second control group, in which the participants drank beverages with maltodextrin alone. They found no evidence that consuming maltodextrin-containing beverages over the seven-day period alters insulin sensitivity and glucose metabolism.
“These results do not support the sweet uncoupling hypothesis,” the authors write. “Rather, they suggest that sucralose consumption alters the metabolism of simultaneously consumed glucose to rapidly produce deleterious effects on metabolic health. Since the extent of this exposure is very likely experienced in a natural setting, our results provide evidence that LCS consumption contributes to the rise in the incidence of impaired glucose tolerance.”