Effects of Sweeteners on the Gut Microbiota: A Review of Experimental Studies and Clinical Trials

Abstract

The consumption of sugar-free foods is growing because of their low-calorie content and the health concerns about products with high sugar content. Sweeteners that are frequently several hundred thousand times sweeter than sucrose are being consumed as sugar substitutes. Although nonnutritive sweeteners (NNSs) are considered safe and well tolerated, their effects on glucose intolerance, the activation of sweet taste receptors, and alterations to the composition of the intestinal microbiota are controversial. This review critically discusses the evidence supporting the effects of NNSs, both synthetic sweeteners (acesulfame K, aspartame, cyclamate, saccharin, neotame, advantame, and sucralose) and natural sweeteners (NSs; thaumatin, steviol glucosides, monellin, neohesperidin dihydrochalcone, and glycyrrhizin) and nutritive sweeteners (polyols or sugar alcohols) on the composition of microbiota in the human gut. So far, only saccharin and sucralose (NNSs) and stevia (NS) change the composition of the gut microbiota. By definition, a prebiotic is a nondigestible food ingredient, but some polyols can be absorbed, at least partially, in the small intestine by passive diffusion: however, a number of them, such as isomaltose, maltitol, lactitol, and xylitol, can reach the large bowel and increase the numbers of bifidobacteria in humans. Further research on the effects of sweeteners on the composition of the human gut microbiome is necessary.

FIGURE 1

Effects of artificial sweeteners and saccharin on gut microbiota. Animal studies have reported specific shifts in the intestinal microbiota related to alterations in the metabolic pathways linked to glucose tolerance after ingestion of saccharin.

FIGURE 2

Natural sweeteners and their effects on gut microbiota. Stevia extracts have been described as capable of changing the gut microbiota composition, although the current effects of stevia on Bacteroides need further study.

FIGURE 3

Effects of polyols on gut microbiota composition. Erythritol, sorbitol, and mannitol do not affect the composition of the gut microbiota; however, lactitol, isomalt, xylitol, and maltitol provoke shifts in the gut microbiome, increasing bifidobacteria numbers in healthy people. The laxative effects of polyols need to be considered when they are consumed by patients with inflammatory bowel disease. C. difficile, Clostridium difficile; N/A, not available.