INTRODUCTION: Functional gastrointestinal disorders (FGIDs) and inflammatory bowel diseases (IBD) present significant challenges for both pediatric and adult populations. The low FODMAP diet (LFD) has gained prominence as an evidence-based dietary intervention, offering symptom relief for abdominal pain, bloating, and altered bowel habits. However, concerns about adherence, nutritional adequacy, and long-term safety remain critical, particularly in pediatric populations. AREAS CERED: This narrative review examines the nature and physiological impact of FODMAPs, focusing on the practical application of the low-FODMAP diet (LFD) in adults and pediatric gastroenterology. Particular attention is given to emerging insights into its impact on gut microbiota and long-term safety. EXPERT OPINION: While LFD effectively alleviates symptoms in FGIDs and functional symptoms in IBD, its restrictive nature demands professional supervision to mitigate nutritional risks. For pediatric patients, adherence and reintroduction protocols require optimization. Further research into personalized dietary approaches and microbiome-targeted strategies could enhance the clinical utility of the LFD, ensuring its long-term safety and efficacy for diverse patient groups. PLAIN LANGUAGE SUMMARY: Many people, both children and adults, experience stomach and bowel problems like pain, bloating, and changes in bowel habits. These symptoms are common in conditions such as functional gastrointestinal disorders (FGIDs). One dietary approach, called the low FODMAP diet (LFD), has been shown to help reduce these symptoms. The diet limits certain types of carbohydrates, called FODMAPs, which are found in foods like some fruits, vegetables, dairy products, and grains. These carbohydrates can ferment in the gut, causing discomfort in some people.This review looks at how the LFD works, its effectiveness, and its safety. Research shows that the diet can reduce symptoms for many people, particularly those with FGIDs, and it can also help people with IBD who experience additional gut symptoms even when their disease is not active. However, the LFD is a restrictive diet, which means it may be hard to follow and could lead to nutritional issues, especially in children, without professional support.The review also explores how the LFD affects gut bacteria, as the diet can reduce some beneficial bacteria. To make the diet more practical, researchers recommend working with dietitians to ensure it is followed safely and effectively. More studies are needed to understand the long-term impact of the LFD and how it can be adapted to different people's needs.This summary aims to explain the benefits and challenges of the LFD, highlighting the importance of professional guidance and further research to improve its use.