Mouse groups consuming NAS in both lean and HFD states were treated with a gram-negative-targeting broad-spectrum antibiotic to test whether the gut microbiota may regulate the observed NAS effects. The antibiotics were ciprofloxacin and metronidazole (“antibiotics A”). A second antibiotic treatment with gram-positive-targeting antibiotic vancomycin (“antibiotics B”) was also conducted.

After four weeks of antibiotic treatment, the differences in glucose intolerance between NAS-drinking mice and the controls were abolished in both the lean and HFD-fed groups for both treatments. These results suggest that NAS-induced glucose intolerance may be mediated by the intestinal microbiota.

Faecal transplantation experiments were conducted to establish a causal relationship between glucose intolerance and the microbiota. The microbiota of lean mice drinking commercial saccharin or glucose (control) was transferred into lean mice that have never encountered saccharin in their diets.

artificial_sweeteners_alter_gut_microbiota_02_web
Source: Fella, S., 2015, “Artificial sweeteners could kick out sensible gut bacteria”, available at http://sooperfella.com/artificial-sweeteners-could-kick-out-sensible-gut-bacteria/

Recipients of the microbiota from saccharin-drinking mice exhibited an impaired glucose tolerance response compared to recipients of the microbiota from control. Transfers of the microbiota composition of HFD-fed mice drinking saccharin also resulted in the same glucose intolerance phenotype.

1

Figure 1: Blood glucose levels over span of 2 hours after intake of artificial sweeteners (saccharin, sucralose, aspartame) or controls (water, sucrose, glucose). Different treatments, with gram-negative-targeting antibiotics (A), gram-positive-targeting antibiotics (B) or no antibiotics, were used. The NAS-fed mice without antibiotic treatment showed the highest levels of glucose intolerance.

 

2

Figure 2: Glycaemic responses of each treatment in mice. The NAS-fed mice without antibiotic treatment showed abnormal glycaemic responses, compared to the controls and the antibiotic-treated mice.

 

Reference: Suez, Jotham et al. ‘Artificial Sweeteners Induce Glucose Intolerance By Altering The Gut Microbiota’. Nature (2014)

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