In a recent review published within the journal Nutrients, researchers in Italy discussed the findings from various pre-clinical and clinical studies that evaluated the effect of non-nutritive sweeteners resembling aspartame, saccharin, sucralose, and acesulfame-K on the gut microbiome.
Review: Effect of Non-Nutritive Sweeteners on the Gut Microbiota. Image Credit: cruspan / Shutterstock
Background
The bacteria that constitute the human gut microbiome comprise over 50 phyla and 1,500 species, with 99% of the bacterial population constituted by 30 to 40 species. The gut microbiota varies from one individual to a different and is influenced by a spread of things resembling age, genetics, antibiotics, and weight loss plan. A healthy balance of helpful bacteria within the gut is often called eubiosis, while an imbalance leading to a proliferation of pathogenic bacteria is often called dysbiosis. Studies have shown that the ratio between the phyla Firmicutes and Bacteriodetes (F/B ratio) is very important in maintaining gut homeostasis, and gut microbiome dysbiosis is linked to a big selection of diseases affecting various organ systems.
The consumption of non-nutritive sweeteners, which have higher sweetness but significantly lower calories than sucrose, has increased lately. The non-nutritive sweeteners approved for consumption vary across countries based on tests for potential carcinogenic effects and other health problems. Nonetheless, evidence from recent studies indicates that consumption of non-nutritive sweeteners could possibly be related to cardiovascular diseases, glucose intolerance, obesity, insulin resistance, and inflammation, with the gut microbiome acting as a possible mediator.
Given the wide use of non-nutritive sweeteners as a result of their low calorific content, and the pivotal role of the gut microbiome on human health, it is crucial to know the potential determinantal effects of non-nutritive sweeteners on the gut microbiome.
Major findings
The review evaluated evidence from studies that examined the effect of 4 non-nutritive sweeteners — aspartame, saccharin, sucralose, and acesulfame-K — on the gut microbiome. Aspartame is a dipeptide methyl ester containing L-phenylalanine and L-aspartic acid — two amino acids commonly present in vegetables, fruits, dairy products, and nuts. Saccharin is a water-soluble organic acid, while acesulfame-K is a hydrophilic derivative of an organic acid. Sucralose is a disaccharide containing 4-chloro-4-deoxygalactose and 1,6-dichloro-1,6-dideoxyfructose, and just isn’t easily metabolized by humans.
Six pre-clinical trials comprising two studies on rat models and 4 on humans have examined the impact of aspartame consumption on the gut microbiota. A study on rat models reported that when combined with a high-fat weight loss plan, aspartame consumption resulted in a lower calorie intake and weight gain, but decreased the insulin-stimulated disposal of glucose, elevated the fasting glucose levels, and increased the F/B ratio.
Amongst humans, studies that examined individuals who consumed aspartame or acesulfame-K reported that while the general bacterial count was not different between individuals who consumed either or each of the 2 non-nutritive sweeteners and individuals who didn’t eat any non-nutritive sweetener, the range of the gut microbiome decreased from 24 phyla to seven phyla.
While one study on humans reported that aspartame consumption didn’t cause changes within the gut microbiome or short-chain fatty acids, one other randomized controlled trial reported that consumption of aspartame and other non-nutritive sweeteners significantly modified the gut microbiome composition and performance.
Studies on mice models that investigated the consequences of acesulfame-K had contrasting results, with some studies reporting no significant change within the fecal microbiome composition, while others indicating increases and reduces within the F/B ratio, intestinal injury, and dysbiosis. The effect of sucralose on the gut microbiota was examined in various studies on mice models and humans, and the outcomes indicated significant changes within the gut microbiome of humans and mice. Changes in mice included a rise in Ruminococcus, Clostridiaceae, Akkermansia, Proteobacteria, Escherichia coli, Firmicutes, and F/B ratio, with increases in pro-inflammatory markers, cholic acid, and cholesterol within the liver.
Similarly, studies examining the impact of saccharin consumption on the gut microbiome of mice reported decreased glucose tolerance and a rise in pro-inflammatory markers within the liver. Nonetheless, studies on the effect of saccharin consumption in dogs, piglets, and humans largely reported no significant effects or changes.
Conclusions
Overall, the review indicated that the findings from studies examining the impact of non-nutritive sweeteners on the gut microbiome in human and animal models have been conflicting. While some clinical trials reported dysbiosis related to non-nutritive sweetener consumption, others reported no significant changes within the gut or fecal microbiomes of humans and animals. Currently, there isn’t any scientific consensus on the biomarkers or outcomes that may determine the impact of non-nutritive sweetener consumption on gut microbiota.