Surprising study reveals why sugar-free candy and gum give some people gas
Sorbitol is commonly found in sugar-free products like gum and candy, as well as in various fruits such as apricots and apples. (CREDIT: Creative Commons)
Researchers at UC Davis have pinpointed changes in the gut microbiome linked to difficulties in digesting sorbitol.
Sorbitol, a type of sugar alcohol, is commonly found in sugar-free products like gum and candy, as well as in various fruits such as apricots and apples. Excessive intake of sorbitol can lead to symptoms like bloating, cramps, and diarrhea, a condition known as sorbitol intolerance.
In a recent study published in the journal Cell, scientists at UC Davis investigated how alterations in the gut microbiome contribute to sorbitol intolerance.
Lead author Jee-Yon Lee, an assistant project scientist in the UC Davis Department of Medical Microbiology and Immunology, explains, "Our research suggests that microbial sorbitol degradation normally protects the host against sorbitol intolerance. However, an impairment in the microbial ability to break down sorbitol causes sorbitol intolerance."
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The team conducted experiments using mice to understand how antibiotics and dietary factors affect the gut microbiota's ability to metabolize sorbitol. They found that treatment with antibiotics, coupled with a high-fat diet, led to a reduction in Clostridia gut microbes, which play a crucial role in sorbitol breakdown.
Using metagenomic analysis, the researchers identified the specific gut bacteria responsible for sorbitol metabolism and observed changes in their abundance following antibiotic treatment. They discovered that Clostridia bacteria, which thrive in low-oxygen environments, were significantly reduced after antibiotic administration.
Further investigation revealed that the combination of antibiotics and a high-fat diet led to decreased oxygen utilization by the gut epithelial cells, resulting in elevated oxygen levels in the gut environment. This oxygen increase inhibited the growth of Clostridia bacteria, impairing sorbitol digestion.
Taking antibiotics, combined with a high-fat diet, reduced the number of Clostridia gut microbes. Image generated with BioRender. (CREDIT: UC Davis Health)
To restore normal sorbitol metabolism, the researchers tested various interventions, including administering Anaerostipes caccae, a gut bacterium that produces butyrate, a short-chain fatty acid. Butyrate promotes oxygen consumption by gut epithelial cells, thereby lowering oxygen levels in the intestine and favoring the growth of Clostridia bacteria. This restoration of Clostridia levels protected the mice from sorbitol-induced diarrhea.
Based on their findings, the researchers propose that mesalazine, a drug commonly used to treat inflammatory bowel diseases like ulcerative colitis and Crohn's disease, could potentially alleviate sorbitol intolerance in humans. Mesalazine functions similarly to butyrate-producing bacteria, helping to maintain low oxygen levels in the intestine conducive to Clostridia growth.
Compositional and functional changes in the microbiota of mice with prolonged sorbitol intolerance. (CREDIT: Cell)
Jee-Yon Lee emphasizes the significance of the discovery, particularly in light of the widespread use of sorbitol in high-fat, keto-friendly diet foods. "This discovery is crucial, given the prevalent use of sorbitol and similar sugar alcohols in the production of keto-friendly diet foods that are high in fat content," Lee says. "It also highlights the importance of oxygen consumption by the epithelial lining in the intestines in maintaining a healthy balance of gut bacteria, especially Clostridia, for proper digestion of certain sugars."
However, it's important to note a key limitation of the study: mice can tolerate much higher sorbitol levels than humans, partly due to anatomical differences in their digestive systems. Clinical trials will be necessary to validate whether mesalazine can effectively treat sorbitol intolerance in humans.
Clostridia are a main source of sorbitol dehydrogenase genes during homeostasis. Mice were maintained on a low-fat (LF) diet or a high-fat (HF) diet for 14 days. (CREDIT: Cell)
Andreas Bäumler, senior author of the study and a distinguished professor in the UC Davis Department of Medical Microbiology and Immunology, underscores the significance of their findings. "Our study provides a completely new starting point for approaches to diagnose, prevent, and treat sorbitol intolerance," Bäumler asserts.
By identifying specific gut bacteria and potential therapeutic interventions, the study offers promising avenues for managing this common digestive disorder.
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