The effect of dietary fibres on intestinal barrier function has not been well studied, especially in the elderly. We aimed to investigate the potential of the dietary fibres oat β-glucan and wheat arabinoxylan to strengthen the intestinal barrier function and counteract acute non-steroid anti-inflammatory drug (indomethacin)-induced hyperpermeability in the elderly. A general population of elderly subjects (≥65 years, n = 49) was randomised to a daily supplementation (12g/day) of oat β-glucan, arabinoxylan or placebo (maltodextrin) for six weeks. The primary outcome was change in acute indomethacin-induced intestinal permeability from baseline, assessed by an in vivo multi-sugar permeability test. Secondary outcomes were changes from baseline in: gut microbiota composition, systemic inflammatory status and self-reported health. Despite a majority of the study population (85%) showing a habitual fibre intake below the recommendation, no significant effects on acute indomethacin-induced intestinal hyperpermeability in vivo or gut microbiota composition were observed after six weeks intervention with either dietary fibre, compared to placebo.

Chronic diarrhea is a frequent presenting symptom, both in primary care medicine and in specialized gastroenterology units. It is estimated that more than 5% of the global population suffers from chronic diarrhea. and that about 40% of these subjects are older than 60 years. The clinician is frequently faced with the need to decide which is the best therapeutic approach for these patients. While the origin of chronic diarrhea is diverse, impairment of intestinal barrier function, dysbiosis. and mucosal micro-inflammation are being increasingly recognized as underlying phenomena characterizing a variety of chronic diarrheal diseases. In addition to current pharmacological therapies, there is growing interest in alternative products such as mucoprotectants, which form a mucoadhesive film over the epithelium to reduce and protect against the development of altered intestinal permeability, dysbiosis, and mucosal micro-inflammation. This manuscript focuses on chronic diarrhea in adults, and we will review recent evidence on the ability of these natural compounds to improve symptoms associated with chronic diarrhea and to exert protective effects for the intestinal barrier.

Irritable bowel syndrome (IBS) is a prevalent gastrointestinal disorder for which effective treatment strategies are insufficient. Butyrate, a microbiota-derived short-chain fatty acid believed to strengthen the intestinal barrier function, might be a potential new treatment option. This study aimed to investigate potential protective effects of acute in vivo butyrate exposure on intestinal barrier function in healthy subjects and patients with IBS. For this, we used an experimental colonoscopy-perfusion model for colon-specific butyrate delivery and adequate tissue sampling. Seventeen IBS and 17 healthy subjects underwent a colonoscopy procedure exposing a predefined colonic area to 100 mmol/L butyrate for 90 min in vivo. Mucosal biopsies collected pre- and post-butyrate exposure were stimulated in Ussing chambers with/without sodium deoxycholate (DC) to induce intestinal hyperpermeability. Intestinal permeability was measured by fluorescein isothiocyanate-dextran and horseradish peroxidase passage. DC-stimulation significantly increased para- and transcellular permeability in biopsies collected pre-butyrate exposure. DC-induced transcellular hyperpermeability was significantly alleviated in biopsies collected post-butyrate exposure compared to pre-exposure in patients with IBS (p = 0.034). In conclusion, we established a colonoscopy research model for colon-specific delivery and sampling and demonstrated acute protective effects of butyrate on transcellular intestinal permeability in patients with IBS. The results support butyrate's potential role in novel treatment strategies in IBS. Clinicaltrials.gov number: NCT05249023.

Strenuous exercise can result in disruption of intestinal barrier function and occurrence of gastrointestinal symptoms. The aim of this exploratory study was to elucidate systemic effects of increased intestinal permeability after high‐intensity exercise. Forty‐one endurance‐trained subjects performed a 60‐min treadmill run at 80% VO₂max. Small intestinal permeability was measured as urinary excretion ratio of lactulose/rhamnose (L/R). Blood, saliva and feces were analyzed for gut barrier and immune‐related biomarkers. The exercise challenge increased several markers of intestinal barrier disruption, immune function and oxidative stress. We found a negative correlation between L/R ratio and uric acid (r = −0.480), as well as a positive correlation between the L/R ratio and fecal chromogranin A in male participants (r = 0.555). No significant correlations were found between any of the markers and gastrointestinal symptoms, however, perceived exertion correlated with the combination of IL‐6, IL‐10 and salivary cortisol (r = 0.492). The lack of correlation between intestinal permeability and gastrointestinal symptoms could be due to minor symptoms experienced in lab settings compared to real‐life competitions. The correlation between L/R ratio and uric acid might imply a barrier‐protective effect of uric acid, and inflammatory processes due to strenuous exercise seem to play an important role regarding physical exhaustion.