Self-Perceived Lactose Intolerance Versus Confirmed Lactose Intolerance in Irritable Bowel Syndrome: A Systematic Review.

Background and aims: Disorders of gut-brain interaction (DGBI) are prevalent, affecting 20-40% of the population, with irritable bowel syndrome (IBS) being the most common and impactful. While congenital lactose intolerance is rare, lactase deficiency in adults is widespread, causing gastrointestinal symptoms like bloating and diarrhea. Self-perceived lactose intolerance often overestimates symptoms, impacting dietary choices and quality of life, necessitating better understanding and management for improved patient outcomes. This article evaluates the diagnostic accuracy of self-reported lactose intolerance in patients with lactose intolerance and IBS through a systematic review.

Methods: A systematic literature search was conducted using PubMed, EMBASE, and SCOPUS, including terms related to IBS, lactose intolerance, and self-reported symptoms, without applying filters to ensure comprehensive coverage. Inclusion criteria focused on observational studies with adult participants diagnosed with lactose intolerance, addressing symptoms and lactose malabsorption, while excluding non-English articles, reviews, editorials, and studies involving pediatric subjects.

Results: The systematic review analyzed six studies with 845 participants, revealing significant variability and moderate accuracy in self-reported lactose intolerance for diagnosing actual lactose intolerance in IBS patients. Hydrogen breath tests (HBTs) showed that self-reported symptoms often led to false positives, underscoring the need for objective diagnostic tools and standardized criteria. The findings highlight the complexity of diagnosing lactose intolerance in IBS patients and suggest that lactose-free diets and routine HBT should not be recommended without clear indications.

Conclusions: The rigorous selection process ensured the inclusion of high-quality, relevant studies, thereby enhancing the reliability and validity of the review's findings. These studies revealed that a lactose-free diet should not be routinely recommended for IBS patients, nor should the routine use of HBT to identify lactose malabsorption in this group. Future research should focus on better understanding the factors influencing lactose perception and tolerance, which is crucial for more effective management of lactose intolerance in IBS patients.