Washing down carbs with diet soft drinks a no

Media Release

4 March 2020

Washing down your hot chips with diet soft drinks may change the brain’s response to sweet taste and the body’s insulin sensitivity and glucose metabolism, according to US research.

In a study publishing 3 March 2020 in the journal Cell Metabolism, researchers say the discrepancies in these studies may be due to how the sweeteners are consumed – or, more specifically, what they are consumed with.

Investigators report that the artificial sweetener sucralose (also known as Splenda) seems to have no negative impact on its own, but when it is consumed with a carbohydrate, it induces deleterious changes in insulin sensitivity and decreases the brain’s response to sweet taste as measured by fMRI.

“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,” says senior author Dana Small, a Neuroscientist who is a Professor of Psychiatry and the Director of the Modern Diet and Physiology Research Centre at Yale University.

“This would be important because sweet-taste perception might lose the ability to regulate metabolic responses that prepare the body for metabolising glucose or carbohydrates in general.”

The trial enrolled 45 volunteers between the ages of 20 and 45 who didn’t normally consume low-calorie sweeteners.

All of them were of healthy weight and had no metabolic dysfunction.

Other than consuming seven beverages in the lab over a two-week period, they didn’t make any changes to their diet or other habits.

The investigators conducted studies on the volunteers 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.

The sweeteners were consumed as fruit-flavored beverages with added sucralose, or with table sugar for comparison.

“Previous studies in rats have shown that changes in the ability to use sweet taste to guide behaviour can lead to metabolic dysfunction and weight gain over time. We think this is due to the consumption of artificial sweeteners with energy,” Ms Small notes.

“Our findings suggest that it’s OK to have a Diet Coke once in a while, but you shouldn’t drink it with something that has a lot of carbs,” she adds.

Future studies will look at whether other artificial sweeteners, as well as more natural sweeteners like stevia, have the same effects as sucralose.

Small expects that many of them will. “It’s hard to say, because we still don’t fully understand the mechanism,” she concludes. “That’s also something we hope to study further, especially in mice.”

To read the full study, visit: 10.1016/j.cmet.2020.01.014

Source: Scimex