For a very long time, non-nutritive sweeteners have been suggested as healthier alternatives to sugar and have been used in food for diabetics. They may not be devoid of problems as many might think, however, according to a new study.
Stevia
Carbohydrates or sugars cause blood glucose levels to go up after consuming them. This upsurge is referred to as the glycemic response.
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The belief has been that non-nutritive sweeteners, such as saccharin, aspartame, and stevia, do not impact glycemic responses. This is because they contain little or no carbohydrates.
However, new research published in the journal Cell is challenging that notion. Scientists found that sugar-free sweeteners can influence human gut microbiomes and alter blood sugar levels as carbohydrates.
Glycemic responses to non-nutritive sweeteners
Senior study author Eran Elinav, a microbiome researcher at Israel’s Weizmann Institute of Science and the German National Cancer Center (DKFZ), carried out an initial study in 2014. In that research, the immunologist and his colleagues made findings that challenged the notion that sugar substitutes are biologically inert. They found that the sweeteners affected mice’s microbiomes in a manner that could alter their glycemic responses.
Therefore, the team wanted to find out in the latest study whether similar effects could be observed in humans.
The researchers recruited and screened more than 1,300 persons who did not have non-nutritive sweeteners in their daily diet. Volunteers numbering 120 passed the strict screening and were randomly assigned to one of six groups. These comprised four sweetener groups and two control groups.
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Subjects who consumed much lower amounts of saccharin, aspartame, stevia or sucralose than daily allowances deemed safe by the FDA were put in the same group.
Elinav and his team found that these sugar substitutes did impact the composition and function of microbes in the gut. They also affected the molecules that microbiomes secrete into the blood.
“This seemed to suggest that gut microbes in the human body are rather responsive to each of these sweeteners,” Elinav explained. “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.”
The researchers found that these sweeteners are not as inert as people might think. There was a high correlation between microbiome changes and alterations in the glycemic responses of consumers.
Probing causation
The team took a step further to be sure that changes in microbes truly triggered the altered glycemic responses. To do this, they took gut microbe samples from volunteers and introduced them into germ-free mice.
The animals were bred in fully sterile conditions and did not have microbiomes of their own.
After the microbial sample transfer, the mice displayed glycemic alterations that were very similar to those seen in sample donors. Microbiomes of the top responder subjects induced significant alterations in the animals but those of bottom responders mostly didn’t.
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“These results suggest that the microbiome changes in response to human consumption of non-nutritive sweetener may, at times, induce glycemic changes in consumers in a highly personalized manner,” said Elinav.
Researchers expect sweetener effects to differ between individuals. This is because of the unique composition of the human gut microbiome.
The clinical implications that the observed changes could have on human health are not known. Attention should be given to this in future research, the team stated.
References
Personalized microbiome-driven effects of non-nutritive sweeteners on human glucose tolerance
