Digestive Enzyme Defect May Trigger IBS Symptoms

A new study has found that genetic variants affecting sucrase, a digestive enzyme, are associated with an increased risk of irritable bowel syndrome (IBS). Researchers analyzed data from over 360,000 individuals in the UK Biobank and identified that defects in the sucrase component of the sucrase-isomaltase (SI) enzyme were linked to both higher IBS risk and more severe gastrointestinal symptoms. The findings suggest that genetic screening could help tailor dietary recommendations for IBS patients.

Sucrase-isomaltase and carbohydrate digestion

Sucrase-isomaltase is a key intestinal enzyme responsible for breaking down dietary carbohydrates, including sucrose and starch. The enzyme consists of two functional parts – sucrase and isomaltase – both of which originate from a single gene. Previous research suggested a link between SI gene variants and IBS, but it remained unclear whether sucrase and isomaltase contribute differently to disease risk and symptom severity.

In this study, researchers investigated whether specific genetic variants affecting sucrase and isomaltase had distinct effects on IBS risk. They examined genetic and health data from a large population to assess the impact of these enzyme defects on gastrointestinal symptoms.

Sucrase defects associated with IBS risk

The analysis revealed that individuals carrying sucrase-related genetic variants had a significantly increased likelihood of developing IBS. These individuals also reported more severe bowel symptoms, including bloating, diarrhoea and abdominal pain. Additionally, sucrase-deficient individuals were more likely to avoid foods high in sucrose, suggesting that their symptoms may be triggered by sucrose consumption.

In contrast, variants affecting isomaltase did not appear to influence IBS risk or symptom severity. This suggests that while both sucrase and isomaltase contribute to carbohydrate digestion, only sucrase deficiencies have a notable impact on gastrointestinal health.

Implications for dietary management and future research

IBS affects millions of individuals worldwide and is often difficult to manage due to its varied causes and symptom presentations. The study’s findings highlight the role of digestive enzyme genetics in IBS and suggest that dietary modifications, such as reducing sucrose intake, may be beneficial for individuals with sucrase-related genetic variants.

“Our results bear potential implications for the development of novel diagnostic tools, dietary strategies, and even enzyme-targeted therapies towards personalized approaches to IBS prevention and treatment”.

Dr. Mauro D'Amato.

While the results provide strong evidence for a link between sucrase deficiency and IBS, further research is needed to validate these findings in different populations. Future studies may also explore enzyme-targeted therapies or genetic screening strategies to guide personalized dietary recommendations.

Reference: Torices L, Bonfiglio F, Esteban-Blanco C, Zamfir-Taranu A, Naim HY, D’Amato M. Domain-specific effects of sucrase-isomaltase genotype in irritable bowel syndrome. Gastroenterol. 2025:S0016508525003622. doi: 10.1053/j.gastro.2025.01.242

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