Since the late 1800s, non-nutritive sweeteners have been used to provide sweetness without sugar. Long been believed to have no effect on the human body, researchers reporting in the journal Cell now challenge this notion by finding that these sugar substitutes are not inert, and, in fact, some can alter human consumers’ microbiomes and thereby their glycaemic responses – albeit in a highly individualised fashion.
Previous research has already found found that non-nutritive sweeteners affected the microbiomes of mice in ways that could impact their glycaemic responses, something which the same researchers now investigated in humans.
To address this important question, the research team carefully screened over 1300 individuals for those who strictly avoid non-nutritive sweeteners in their day-to-day lives, and identified a cohort of 120 individuals. These participants were broken into six groups: two controls and four who ingested well below the FDA daily allowances of either aspartame, saccharin, stevia, or sucralose.
“In subjects consuming the non-nutritive sweeteners, we could identify very distinct changes in the composition and function of gut microbes, and the molecules they secret into peripheral blood. This seemed to suggest that gut microbes in the human body are rather responsive to each of these sweeteners,” said senior author Eran Elinav, an immunologist and microbiome researcher. “When we looked at consumers of non-nutritive sweeteners as groups, we found that two of the non-nutritive sweeteners, saccharin and sucralose, significantly impacted glucose tolerance in healthy adults. Interestingly, changes in the microbes were highly correlated with the alterations noted in people’s glycaemic responses.”
To prove the microbiomes were responsible, the researchers transferred microbial samples from the study subjects to mice that have been raised in completely sterile conditions, with no microbiome of their own.
“The results were quite striking,” explained Elinav. “In all of the non-nutritive sweetener groups, but in none of the controls, when we transferred into these sterile mice the microbiome of the top responder individuals collected at a time point in which they were consuming the respective non-nutritive sweeteners, the recipient mice developed glycaemic alterations that very significantly mirrored those of the donor individuals. In contrast, the bottom responders’ microbiomes were mostly unable to elicit such glycaemic responses,” he added. “These results suggest that the microbiome changes in response to human consumption of non-nutritive sweetener may, at times, induce glycaemic changes in consumers in a highly personalised manner.”
Elinav says that he expects the effects of the sweeteners will vary across individuals because of how unique our microbiomes are. “We need to raise awareness of the fact that non-nutritive sweeteners are not inert to the human body as we originally believed. With that said, the clinical health implications of the changes they may elicit in humans remain unknown and merit future long-term studies.”
“In the meantime, we need to continue searching for solutions to our sweet tooth craving, while avoiding sugar, which is clearly most harmful to our metabolic health,” says Elinav. “In my personal view, drinking only water seems to be the best solution.”
Source: Science Daily
