PhD Scientific Days 2026

Health Sciences 1.

Low-FODMAP Diet and Nutritional Concerns in SIBO–IBS Overlap

Name of the presenter

MENEZES, Hana Shania

Institute/workplace of the presenter

Semmelweis University

Authors

Hana Shania Menezes¹
1: Semmelweis University

Text of the abstract

Small Intestinal Bacterial Overgrowth (SIBO) shares significant symptom overlap with IBS, making it an important differential diagnosis. The low-FODMAP diet (LFD) may help manage symptoms by reducing fermentable carbohydrate intake and intestinal gas production; however, it does not eliminate bacterial overgrowth. As the LFD is restrictive, adherence and nutritional adequacy remain important concerns.

To investigate the relationship between LFD adherence and nutritional status in patients with SIBO presenting with IBS-like symptoms.

This study employs a cross-sectional design complemented by a systematic search of Scopus, Embase and PubMed from 2021 to 2026, following PRISMA. Participants include individuals diagnosed with SIBO via breath testing (HBT), meeting Rome IV criteria for IBS, treated with an oral antibiotic (Xifaxan) and probiotics, and advised by a dietitian to follow the LFD. Dietary adherence is assessed using a 3-day food diary and the FODMAP Adherence Rating Scale questionnaire. Nutritional status is assessed using bioelectrical impedance analysis, focusing on fat-free mass index, fat mass, body fat percentage, and visceral fat. Gastrointestinal symptoms are evaluated using a retrospective, self-reported Bristol Stool Scale to compare pre- and post-diet stool patterns.

The 26 included studies indicate limited evidence for recommending the LFD. Some studies showed symptom improvement in IBS-like or mixed IBS/SIBO populations, but results were often not separated for confirmed SIBO cases. Prolonged restriction may affect nutritional adequacy, including fibre, calcium, iron, zinc, folate, B vitamins, vitamin D, and vitamin B12, and may reduce beneficial bacteria, especially Bifidobacteria.

The LFD may be useful as a short-term, supervised symptom-management strategy. It should not be viewed as an independent treatment option for SIBO eradication. It should be personalized, with phased reintroduction based on individual tolerance to limit nutritional deficiencies and support gut microbial diversity. Therefore, greater emphasis should be placed on patient education and the proper implementation of the diet.

IT WAS PREPARED WITH THE PROFESSIONAL SUPPORT OF THE MINISTRY OF CULTURE AND INNOVATION'S UNIVERSITY RESEARCH
SCHOLARSHIP PROGRAM 2025-2.1.1-EKÖP-2025-00014, FINANCED FROM THE NATIONAL RESEARCH, DEVELOPMENT AND INNOVATION
FUND