The Impact of Sugar Substitutes Like Erythritol on the Gut Microbiome

1. Gut Microbiome
2. Sugar Substitutes, Sweeteners, and Sugar Alcohols
2.1 Sugar Substitutes
2.2 Sweeteners
3. Studies on the Influence of Sweeteners on the Microbiome
3.1 Erythritol
3.2 Xylitol
3.3 Isomalt
4. The Dose Makes The Poison

1. Gut Microbiome

The gut microbiome, also called the gut flora, refers to the community of microorganisms—primarily bacteria, but also archaea and fungi—that reside in the human digestive tract. These microbes play a vital role in maintaining overall gut health, and their composition can vary significantly from person to person.
While some microbial patterns are considered beneficial, others may be linked to common gut conditions such as IBS, SIBO, and chronic abdominal pain. A disrupted or imbalanced microbiome may influence the development of these conditions, making microbiome-focused care increasingly important in gastroenterology.
In leading clinics—especially in cities like London where gut health is a growing focus—doctors often recommend targeted probiotic support to restore balance. A healthy microbiome helps regulate the immune system, synthesizes key vitamins, supports metabolic function, and protects against harmful pathogens. If you struggle with bloating, diarrhea, or other digestive symptoms, you may benefit from a personalized microbiome assessment.

2. Sugar Substitutes, Sweeteners, and Sugar Alcohols

Sugar replacements or sweeteners are substances used in food products as alternatives to sugar. These alternatives include artificial sweeteners and sugar substitutes.

2.1 Sugar Substitutes

Here in Germany, sweeteners are legally categorized into artificial sweeteners and sugar substitutes (2). Sugar substitutes (also called bulk sweeteners) include xylitol, erythritol, sorbitol, isomalt, and mannitol (2).

2.2 Sweeteners

Artificial sweeteners also known as non-caloric sweeteners (NAS) or non-sugar sweeteners (NSS), are increasingly used as alternatives to sugar—especially in weight management. Common examples include aspartame, sucralose, stevia, advantame, saccharin, and acesulfame.The consumption of artificial sweeteners as a sugar alternative has become increasingly popular in recent years, especially for weight management. The German Food Association classifies artificial sweeteners as additives that sweeten food but, unlike sugar and sugar substitutes, do not provide energy[und] and have no impact on blood sugar levels or dental health[haben] (1).
However, doctors and nutrition experts in gut-focused clinics—are increasingly examining how these sweeteners affect digestive conditions like IBS, SIBO, and other common disorders. While they are often marketed as low-calorie or diabetic-friendly, you may still experience gut symptoms depending on your individual tolerance.

3. Research on the Effects of Sweeteners on the Microbiome

There is increasing debate within the gastroenterology community about the impact of sugar substitutes on the gut. Some studies have raised concerns that certain artificial sweeteners and sugar alcohols may negatively affect the gut microbiome, especially in people with common gut conditions like IBS or SIBO.
In leading clinics, particularly in London, doctors are starting to examine how these sweeteners may influence symptoms such as bloating, abdominal pain, and diarrhea—especially in patients already following low-FODMAP or probiotic-supported diets.

3.1 Erythritol

Erythritol (E-968) is a common sugar alcohol often promoted as a healthy, low-calorie alternative to regular table sugar. It’s widely used in products marketed to people with gut-sensitive conditions and those trying to lose weight or manage blood sugar levels.
While erythritol is often labeled “calorie-free,” this is not entirely accurate. 100g of erythritol provides around 20 kcal—far lower than sucrose (which provides about 400 kcal per 100g).

Despite being significantly lower in energy content, erythritol is also less sweet—approximately two-thirds as sweet as sucrose. You may notice it more often in “sugar-free” snacks or protein bars, where higher amounts are added to reach the desired sweetness.

Although erythritol occurs naturally in some fruits and foods, the amounts are so small that commercial erythritol must be produced biotechnologically.

Erythritol is rapidly absorbed in the small intestine, meaning only a small portion reaches the large intestine (2). In the colon, erythritol is metabolized by the gut microbiome (2). However, as of June 2024, research on the effects of this metabolism on gut microbiome composition remains inconclusive (3).

3.2 Xylitol

Xylitol is slowly absorbed in the digestive tract, allowing part of it to reach the colon, where it is fermented by the gut flora into short-chain fatty acids (SCFAs) (2,4). These SCFAs are known to support a healthy gut barrier and may offer probiotic-like benefits. However, this fermentation process also produces gas (2), which can trigger bloating, abdominal discomfort, or even diarrhea in sensitive individuals.
In gastroenterology clinics, particularly in London, doctors often monitor xylitol intake in patients with IBS or SIBO, as responses can vary. You may tolerate xylitol well in low amounts, but higher doses could lead to discomfort depending on your microbiome profile.

Studies on xylitol’s impact on the gut microbiome remain mixed. While a 2021 study (Xiang et al.) (4) found no significant microbiome changes in mice, earlier research (Uebanso et al., 2017) (5) suggested that xylitol supplementation may alter microbial balance. For those with gut-related conditions, it’s essential to assess tolerance on an individual basis with guidance from a qualified clinic.

3.3 Isomalt

Isomalt bypasses absorption in the small intestine and travels to the colon, where it acts as a nutrient source for certain gut bacteria. This fermentation process may enhance probiotic species like Bifidobacteria, which are commonly promoted in gut health programs (2).
A 2006 study (Gostner et al.) (6) found that isomalt supplementation increased beneficial microbes in the gut microbiome, supporting its classification as a prebiotic carbohydrate. For patients with IBS, SIBO, or other common gut conditions, doctors may recommend low doses of isomalt in the context of a structured plan—especially in gut-focused clinics that include microbiome evaluation.

4. The Dose Makes The Poison

Research on sugar substitutes and their effects on the gut microbiome is still evolving. While some sugar alcohols show probiotic potential or low-FODMAP compatibility, others can contribute to unwanted symptoms like abdominal pain, bloating, or diarrhea—especially if you consume them in large amounts.
As with many aspects of gastroenterology, moderation matters. You may benefit from small quantities, but higher doses might disturb your microbiome balance. Functional clinics in London and elsewhere often emphasize individualized tolerance assessments and may recommend probiotic support, dietary tracking, or breath testing when addressing these gut-related conditions.

References

1. Bewertung von Süßstoffen und Zuckeraustauschstoffen (bund.de); latest check 04.06.2023
2. Plaza-Diaz J, Pastor-Villaescusa B, Rueda-Robles A, Abadia-Molina F, Ruiz-Ojeda FJ. Plausible Biological Interactions of Low- and Non-Calorie Sweeteners with the Intestinal Microbiota: An Update of Recent Studies. Nutrients. 2020 Apr 21;12(4):1153. doi: 10.3390/nu12041153. PMID: 32326137; PMCID: PMC7231174.
3. Wojtus, M.; Tomaszuk, S.; Wasik, K.; Polyols – What do we know about their impact on the gut microbiome?; Journal of Education, Health and Sport; Online 17 November 2022; Vol. 12, no. 12, pp. 146-151; [Accessed 16 June 2024]. DOI 10.12775/JEHS.2022.12.12.023
4. Xiang S, Ye K, Li M, Ying J, Wang H, Han J, Shi L, Xiao J, Shen Y, Feng X, Bao X, Zheng Y, Ge Y, Zhang Y, Liu C, Chen J, Chen Y, Tian S, Zhu X. Xylitol enhances synthesis of propionate in the colon via cross-feeding of gut microbiota. Microbiome. 2021 Mar 18;9(1):62. doi: 10.1186/s40168-021-01029-6. PMID: 33736704; PMCID: PMC7977168.
5. Uebanso T, Kano S, Yoshimoto A, Naito C, Shimohata T, Mawatari K, Takahashi A. Effects of Consuming Xylitol on Gut Microbiota and Lipid Metabolism in Mice. Nutrients. 2017 Jul 14;9(7):756. doi: 10.3390/nu9070756. PMID: 28708089; PMCID: PMC5537870.
6. Gostner A, Blaut M, Schäffer V, Kozianowski G, Theis S, Klingeberg M, Dombrowski Y, Martin D, Ehrhardt S, Taras D, Schwiertz A, Kleessen B, Lührs H, Schauber J, Dorbath D, Menzel T, Scheppach W. Effect of isomalt consumption on faecal microflora and colonic metabolism in healthy volunteers. Br J Nutr. 2006 Jan;95(1):40-50. doi: 10.1079/bjn20051589. PMID: 16441915.