Replacing sugar with artificial sweetener may help your gut microbiome

Using low-calorie sweeteners instead of sugar appears to stimulate beneficial gut microbes and help people maintain weight loss. Results from one of the longest studies of sweeteners to date indicate that these products may not be as harmful as some studies suggest.

A number of studies in recent years have raised concerns that some low-calorie sweeteners may not be as healthy as they seem. They are a popular option for those trying to lose weight, but research has shown that they may incite hungerincrease blood sugar level or increase the risk heart attacks and strokes. In 2023 World Health Organization issued guidance advising against using low-calorie sweeteners for weight control.

But long-term studies of sweeteners, especially in the context of a healthy diet, are lacking. So Ellen Blaak at Maastricht University in the Netherlands tracked their effects on people who used them as a sugar substitute. She and her colleagues recruited 341 overweight or obese adults in Europe and put them on a low-calorie diet for two months, resulting in an average weight loss of 10 kilograms.

Afterwards, participants ate a healthy diet that included less than 10 percent of their calories from sugar. During this weight maintenance period, 171 participants were advised to avoid sweeteners altogether, and the remainder were advised to replace sugary foods and drinks with alternatives made with low-calorie sweeteners. Participants used at least 16 types of sweetener, and everyone could use as many types as they wanted.

After 10 months, participants in the low-calorie sweetener group maintained an average of 1.6 kilograms more weight loss than the sugar group. They also had higher numbers of gut bacteria that produce short-chain fatty acids, beneficial compounds that previous research shows help regulate blood sugar, support heart health, and promote weight loss and maintenance.

“This shows that, at the very least, replacing sugar in your diet with non-nutritive sweeteners may help you maintain your body weight,” Blaak says. She said the results of this study may differ from previous ones because it was longer and because it looked at the use of sweeteners along with a healthy diet. Additionally, past studies have tended to focus on just a few low-calorie sweeteners rather than many of them together.

When it comes to differences between gut bacteria, our understanding of the microbiome is still in its infancy, he says. Eran Elinav at the Weizmann Institute of Science in Israel. So it's difficult to interpret how changes in the sweetener-using group might affect their health, he says, noting that it's also unclear whether the changes occurred as a result of weight loss, low-calorie sweeteners, or both.