Impaired glycemic response from saccharin.
The researchers recruited into the study only healthy volunteers who did not consume any in their daily diet. A total of 120 individuals passed the stringent screening test and the researchers randomly assigned them to one of six supplementation groups: aspartame, saccharin, stevia, sucralose, glucose (to control for potential interference from glucose in standard NNS formulations), and no supplement (the second control group).
All the sweeteners were given as commercially available sachets, containing a mixture of glucose and in doses lower than the FDA-recommended acceptable daily intake.
To investigate the effect of NNSs on glycemic response, participants wore a continuous glucose monitor throughout the clinical trial, and completed glucose tolerance tests on pre-determined days. The glucose tolerance test measures the body’s ability to absorb and use glucose (sugar).
The researchers found that the groups consuming saccharin and sucralose had a “significantly elevated” glycemic response during exposure to the NNS. No significant effect on glucose tolerance was observed in the aspartame, stevia, glucose, and the no-supplement groups.
These findings suggest that the short-term consumption of saccharin and sucralose in doses lower than the acceptable daily intake can impact glycemic responses in healthy individuals.
Sweeteners can alter the gut microbiome
Based on the findings of animal model studies, the researchers hypothesized that NNSs can affect human metabolism via altering the intestinal microbiome. To test their hypothesis, the researchers analyzed the participants’ stool microbiome samples before and after NNS consumption.
They found that all four tested NNSs altered the bacteria in the gut and the molecules they secrete. Similarly, the four NNSs “distinctly impacted” the oral microbiome.
Such microbiome changes did not occur in the control groups. These findings suggest that NNSs are not inert to the human microbiome.To determine whether microbiome changes were indeed the cause of altered glycemic responses, the researchers transplanted gut bacteria from the study participants into germ-free mice—mice that had been raised in completely sterile conditions and had no microbiome of their own.
Collectively, these mice showed glycemic responses which mirrored those of their human microbiome donors.
These results suggest that human microbiome responses to NNSs are highly personalized and may lead to glycemic alterations in some, but not all consumers, depending on their microbiomes and NNSs they consume.
The idea that the human gut microbiome may respond to certain food additives and trigger metabolic changes is not a new one. Previous studies have suggested that dietary promote metabolic changes through microbiome alteration.
More recently, researchers found that a new low-calorie sweetener promotes the growth of beneficial gut bacteria, which impacts overall health.
Research on other sweeteners
When asked about the study’s limitations, Dr. Elinav noted that the clinical trial only included healthy, non-overweight, normoglycemic individuals, and participants were administered only one NNS formulation.
“Our results call for further randomized, non-industry-sponsored interventional studies in at-risk populations, such as pre-diabetics and diabetics. Other NNS[s], formulations, and doses should be further explored,” said Dr. Elinav.
“Additionally, NNS impacts should be compared in future controlled trials between consumers of carbohydrate-rich and [carbohydrate]-restrictive diets for their potential differential effects on human metabolic physiology. A longer exposure period than the one utilized in our study may be required to fully assess the potential health ramifications mediated by the altered microbiome upon consumption of different NNS[s].
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