The artificial sweetener acesulfame potassium affects the gut microbiome and body weight gain in CD-1 mice

Abstract

Artificial sweeteners have been widely used in the modern diet, and their observed effects on human health have been inconsistent, with both beneficial and adverse outcomes reported. Obesity and type 2 diabetes have dramatically increased in the U.S. and other countries over the last two decades. Numerous studies have indicated an important role of the gut microbiome in body weight control and glucose metabolism and regulation. Interestingly, the artificial sweetener saccharin could alter gut microbiota and induce glucose intolerance, raising questions about the contribution of artificial sweeteners to the global epidemic of obesity and diabetes. Acesulfame-potassium (Ace-K), a FDA-approved artificial sweetener, is commonly used, but its toxicity data reported to date are considered inadequate. In particular, the functional impact of Ace-K on the gut microbiome is largely unknown. In this study, we explored the effects of Ace-K on the gut microbiome and the changes in fecal metabolic profiles using 16S rRNA sequencing and gas chromatography-mass spectrometry (GC-MS) metabolomics. We found that Ace-K consumption perturbed the gut microbiome of CD-1 mice after a 4-week treatment. The observed body weight gain, shifts in the gut bacterial community composition, enrichment of functional bacterial genes related to energy metabolism, and fecal metabolomic changes were highly gender-specific, with differential effects observed for males and females. In particular, ace-K increased body weight gain of male but not female mice. Collectively, our results may provide a novel understanding of the interaction between artificial sweeteners and the gut microbiome, as well as the potential role of this interaction in the development of obesity and the associated chronic inflammation.

Fig 1. Effects of four weeks of Ace-K consumption on the body weight gain and gut microbiome composition of CD-1 mice.

(A) The body weight gain of Ace-K-treated male mice was significantly higher than that of the control male mice, while the body weight gain of female mice was not significantly different from that of the controls. (B) Ace-K consumption altered the composition of gut bacteria in female mice. The abundances of Lactobacillus, Clostridium, an unassigned Ruminococcaceae genus and an unassigned Oxalobacteraceae genus were significantly decreased, and the abundance of Mucispirillum was increased after Ace-K consumption. (C) Ace-K consumption altered the composition of gut bacteria in male mice. The abundances of Bacteroides, Anaerostipes and Sutterella were significantly increased after Ace-K consumption (*p<0.05, **p<0.01, ***p<0.001, N.S. p>0.05).

Fig 2. Functional gene enrichment analysis showing that functional genes related to carbohydrate metabolism were significantly decreased in Ace-K-treated female mice (p<0.05 for all genes listed here).

Fig 3. Functional gene enrichment analysis showing that functional genes related to carbohydrate metabolism were significantly increased in Ace-K-treated male mice (p<0.05).

Genes involved in carbohydrate transport (A), glycolysis and the TCA cycle (B), as well as carbohydrate degradation and fermentation (C), were consistently increased.

Fig 4. Multiple genes encoding pro-inflammatory mediators were significantly increased in male and female mice after Ace-K consumption (p<0.05).

Genes encoding LPS metabolism proteins (A) and flagella components (B) were increased in Ace-K-treated female mice. Genes encoding LPS metabolism proteins (C) and thiol-activated cytolysin (D) were increased in Ace-K-treated male mice.

Fig 5. Ace-K consumption changed the fecal metabolome of female (A, B) and male (C, D) mice, as illustrated by the cloud and PLS-DA plots.

Fig 6. Ace-K consumption significantly altered key fecal metabolites in female (A) and male (B) mice (*p<0.05, **p<0.01).