Review article: the impact of diet on ileoanal pouch function and on the pathogenesis of pouchitis

Abstract

SummaryBackgroundThere is expanding interest in the role that diet plays in ileoanal pouch function and in the pathogenesis of pouchitis.AimsTo present a narrative review of published literature regarding the relationship of diet with pouch function and the pathogenesis of pouchitis, and to provide potentially beneficial dietary strategies.MethodsCurrent relevant literature was summarised and critically examined.ResultsDietary components influence pouch function via their effect on upper gastrointestinal transit, small bowel water content and the structure and fermentative activity of the pouch microbiota. FODMAPs in fruits and vegetables appear to affect pouch function the most, with intake positively associated with increased stool frequency and reduced consistency. Dietary factors that influence the pathogenesis of pouchitis appear different and, at times, opposite to those better for optimising function. For example, risk of pouchitis appears to be inversely associated with intake of fruits. The food components mechanistically responsible for this observation are not known, but a rich supply of fermentable fibres and micronutrients in such foods might play a beneficial role via modulation of microbial community structure (such as increasing diversity and/or changing microbial communities to favour ‘protective’ over ‘pathogenic’ bacteria) and function and/or anti‐inflammatory effects.ConclusionAvailable data are weak but suggest tailoring dietary recommendations according to pouch phenotype/behaviour and pouchitis risk might improve outcomes. More sophisticated dietary strategies that utilise the physiological and pathophysiological effects of dietary components on ileoanal pouches have potential to further improve outcomes. Well designed, adequately powered studies are required.

A novel Monash Pouch diet in patients with an ileoanal pouch is tolerable and has favorable metabolic luminal effects

“…Despite targeting foods naturally high in oligosaccharides in a population with high rates of food intolerances, 3 tolerability scores were rated highly as was acceptability, with all but two patients interested in implementing the diet long term. Factors contributing to the good tolerability are likely to include the net reduction of FODMAP intake on the diet as increases in oligosaccharide were offset by the reduction in excess fructose, polyols and lactose, the initial gradual adaptation period, 19 , 20 and the sufficient variety for flexibility of food choice, as reflected in the participants' acceptability responses of finding the diet having good variety.…”

“…The pathogenesis of pouchitis results from the interaction of an abnormal pouch mucosal immune system with the microbiota, 3 both of which may potentially be influenced by diet. Dietary factors provide key substrates for bacteria that release putatively pathogenic metabolites such as increased hydrogen sulfide (H 2 S), 4 and decreased short‐chain fatty acids (SCFA), such as butyrate, 5 functional alterations that likely characterizes the pouch microbiota 3 . Supplementation of fermentable fibers such as oligosaccharides and resistant starch is associated with increased abundances of Lactobacillus and Bifidobacterium spp.…”

“…This has previously been demonstrated in an ex vivo study where fructo‐oligosaccharides (FOS) markedly lowered fecal H 2 S production by >80% 11 . Additionally, dietary factors, such as osmotically active, slowly absorbed, and rapidly fermentable carbohydrates (e.g., fermentable oligo‐, di‐ and monosaccharides and polyols [FODMAPs]), via their effect on upper gastrointestinal transit, small bowel water content, and fermentation by pouch microbiota, exert effects on the frequency of pouch emptying and fecal characteristics independent of their potential impact on pouchitis pathogenesis 3 …”

“…One dietary approach called the ‘Monash Pouch diet’ has been designed to hypothetically minimize H 2 S production and correct SCFA deficiency via manipulation of pouch fermentation and dissimilatory sulfate reduction pathways and reduce the free‐water content of ileal effluent. 3 , 12 However, before embarking on more definitive exploration of the clinical efficacy of this diet, three questions need to be addressed. First, are changes to dietary intake tolerated in patients with ileoanal pouches?…”

The aetiology of pouchitis in patients with inflammatory bowel disease

“… 45 C. perfringens is a mucin-degrading bacteria, whereas Lactobacilli and Bifidobacteria are known to inhibit the growth of potentially pathogenic bacteria, which may explain the role changes in their respective population numbers plays in the aetiology of pouchitis. 46 …”