High-Fiber Foods: Beneficial or Detrimental in Gastroesophageal Reflux Disease with Irritable Bowel Syndrome

Gastroesophageal reflux disease (GERD) is a prevalent condition wherein stomach contents flow back into the esophagus, leading to a decline in quality of life due to persistent symptoms and potential complications. Irritable bowel syndrome (IBS) is a chronic and widespread disorder of the large intestine, characterized by various symptoms including bloating, gas, and constipation. Although pharmacotherapy remains the main treatment strategy for GERD and IBS, lifestyle modifications and dietary changes, in particular, exhibit a key supportive role in managing the condition. Despite the common belief that dietary fiber suppresses GERD and IBS by improving gut health and motility, some individuals experience worsening reflux symptoms after high-fiber intake, suggesting that fiber intolerance may play a crucial role. Likewise, though dietary fiber is associated with abundant short- and long-term health benefits in children, the ideal amount and the nature of fiber intake in infants and children need to be defined, as even children can experience acid reflux due to fiber intolerance. Nevertheless, limited data exist on the effectiveness of nutritional interventions in patients (children and adults) with coexisting GERD and IBS and fiber intolerance, in particular. Aging, in fact, worsens fiber intolerance in some individuals, which also needs to be explored. This review aims to revisit the recent literature on the relationship between dietary fiber and acid reflux, with special emphasis on the role of fiber intolerance, nickel sensitivity, and histamine intolerance in worsening GERD symptoms. Furthermore, the types of soluble and insoluble fibers, fiber fermentation effects, gastrointestinal motility, and the presence of coexisting GERD and IBS with regard to age were also discussed, simultaneously emphasizing the significance and the need for functional foods. The key conclusion from this review is the emphasis on individual assessment concerning the impact of dietary fiber as the prime importance, since gastrointestinal responses can vary significantly due to interindividual differences in gut physiology and function.