Artificial sweeteners have puzzled nutritionists for some time now. There are studies that suggest they are at least as bad as the sugar they replace for weight gain, while others show the opposite. A new paper suggests it all depends on the context in which they're consumed.
Let's focus on the primary question – are artificial sweeteners beneficial for obesity and diabetes control? The blizzard of conflicting information is deeply unhelpful to anyone choosing a diet. If half the studies are wrong but we don't know which half, why should anyone believe anything?
According to Yale University's Professor Dana Small, no one may be wrong, they're just testing different circumstances. Small had people drink fruit-flavored beverages containing sucralose, sugar, or sucralose and maltodextrin (a carbohydrate without a sweet taste). In Cell Metabolism, she found that those who had the sucralose with maltodextrin showed the negative effects reported by some previous studies. Those whose drinks didn't include maltodextrin were unaffected. Sucralose/maltodextrin drinkers experienced alterations to the body's insulin sensitivity and glucose metabolism. fMRI scans also revealed changes in their brains' responses to sweetness.
It's believed these changes may cause people to consume high-calorie foods and interfere with the body's ability to process what it receives. In some animal studies, sweeteners were found to dull their ability to taste naturally sweet foods, leading to additional consumption to get the same level of reward.
Subsequent tests showed that maltodextrin produced none of these effects on its own; it was only the combination that was problematic. Previous trials seldom involved maltodextrin, but often saw sweeteners consumed with other carbohydrate-rich foods.
"When we set out to do this study, the question that was driving us was whether or not repeated consumption of an artificial sweetener would lead to a degrading of the predictive ability of sweet taste," Small said in a statement. "This would be important because sweet-taste perception might lose the ability to regulate metabolic responses that prepare the body for metabolizing glucose or carbohydrates in general."
Like most nutritional trials, the sample Small used was, well, small – just 45 people consuming seven drinks over a 10-day period. It will take larger studies with more tests to see if they really have explained the discrepancies between previous papers. Small hopes to investigate other sweeteners in the future, but in the meantime says this work “has changed the way that I eat, and what I feed my son.” A Diet Coke on its own is fine, she thinks, but not while eating a carb-rich meal.
Rather than anyone having messed up their results, let alone falsified them, the problem may simply have been generalizing too much from specific situations.