Controversies and reality of the FODMAP diet for patients with irritable bowel syndrome.

Since its first trial showing evidence of efficacy for managing symptoms of irritable bowel syndrome, the fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAP) diet has been gaining popularity but not without criticism. Application of the diet has changed from a rigid list of "allowed" and "not allowed" foods to a structured program of initial FODMAP restriction followed by food reintroduction and finally personalization so that patients are empowered to adjust their diet themselves to achieve good predictability of symptoms. Safety concerns of the diet have centered around its initial elimination leading to compromise of nutritional and psychological health, but careful patient assessment and management, preferably through a FODMAP-trained dietitian, will reduce the risk of such negative health outcomes. Most negative attention for the FODMAP diet has been the notion that it will ruin the microbiota. Controlled studies have indicated that reducing FODMAP intake has no effects on bacterial diversity but will reduce total bacterial abundance, and higher FODMAP intakes will increase health-promoting bacteria, supporting the concept of the full FODMAP program, including attaining a minimal "maintenance" level of FODMAP restriction. This review addresses all these concerns in detail and how to overcome them, including the use of a "FODMAP-gentle" diet, describing restriction of a select few foods very concentrated in FODMAPs. This version of the diet is commonly applied in practice by experienced FODMAP-trained dietitians but is not clearly described in literature. Careful direction and assessment of response or nonresponse will decrease the risks of over-restriction and under-restriction of diet.