Food in functional gastro-intestinal disorders: friend or foe?

Fibre is an important nutrient in the human diet, that is essential for human health. In children, low-fibre diets can cause several disorders like irritable bowel syndrome, constipation, allergies and immune-related disorders. In pediatric practice, concerns exist over tolerance of dietary fibre which may lead to unnecessary restrictions. One reason is that fibre has often been described by its physicochemical properties (solubility/viscosity), rather than its physiological effects (fermentability, bulking effects).

This article (Hojsak, 2022) provides evidence on health benefits on dietary fibre and recommendations for healthy children and those with functional gastrointestinal disorders.

Dietary fibre recommendations for children should differentiate quantity from quality

Current recommendations for daily fibre intake for children vary and suggest a daily amount of fibre approximatively of 10 g/day for young children increasing to around 20 g/day for adolescents. These recommendations are rarely met by children. In UK, only 14% of children aged 4-10 years met the recommendation established by SACN (20g/d) (NDNS, 2020).

However, the current recommendations for daily fibre intake refer to total fibre regardless of the source or fibre quality provided. Yet, different fibre types, and fibre from different sources, have markedly different physiological effects and functions providing benefits within and beyond the human gut once consumed , showing the necessity to take these aspects into account.

The importance of the quality of fibre consumed is increasingly recognized:

• fermentable fibre  are essential for maintaining a healthy microbiome, with benefits within and beyond the gut;
• bulking fibre, which are non or poorly fermentable, are predominantly insoluble. Insoluble fibre provide faecal bulk, stimulate bowel movement, dilute the colonic content (thereby protecting the gut from harmful substances) and adsorb undesirable colonic contents (certain xenobiotics) (Table2).

Table 2: Examples of fermentable and bulking plant-based fibre

Dietary fibre has an effect on gut health and beyond

Fermentation of fibre in the human gut results in the production of short-chain fatty acids (SCFAs) which stimulate gut motility   and have multiple benefits within and beyond the gut including maintaining the effective barrier function of the gut wall and anti-inflammatory properties (Gill, 2020; Rowland, 2018; Stephen, 1980). These anti-inflammatory effects have potential benefits in terms of preventing or improving autoimmune diseases such as diabetes, inflammatory arthritis, inflammatory gastrointestinal disorders and allergic disease (Roduit, 2019).

Epidemiological and interventional studies have demonstrated health benefits of dietary fibre including cholesterol lowering, glycemic control, prevention of constipation, diverticular disease, weight control and, more recently, cognition in prepubertal children (Naveed, 2020; Khan, 2015) .

Other effects have been studied like prevention in chronic disease. In 2015, a meta-analysis of epidemiological studies in adults has shown an association between an increase in dietary fibre of 7 g/d and a statistically significant decrease in the risk of cardiovascular disease, haemorrhagic and ischemic stroke, colorectal cancer and diabetes (SACN, 2015).

Encouraging fiber intake in children with gastrointestinal problems seems necessary for better general health

Functional gastrointestinal disorders, such as infant regurgitation, infant rumination, infant colic, functional diarrhea, functional abdominal pain disorders, and functional defecation disorders in children and adolescents (Benninga, 2016; Hyams, 2016), are a common problem in children (20-32%) (Scarpato,2018) . Data suggest that a balanced diet including a source of fiber may promote a healthy microbiome and thus reduce the risk of some of these diseases, while promoting the overall health of children with functional gastrointestinal problems. However, the studies conducted did not distinguish between the different types of fiber.

Childhood constipation is a complex problem and poor fibre intake appears to have a causal link with its development. Indeed, including fibre from different sources to ensure intake of both fermentable and bulking fibre may support a healthy microbiome and help to prevent some forms of constipation in children. The European Society for Pediatric Gastroenterology, Hepatology and Nutrition (ESPGHAN) and North American Society For Pediatric Gastroenterology, Hepatology & Nutrition (NASPGHAN) recommend fibre intake for children with functional constipation. However, those guidelines do not provide any specific guidance on the type or source of fibre that might be most beneficial.

Further studies are needed to ensure that dietary recommendations include not only the amount of fibre to be achieved but also the type of fiber to be favored for healthy children and those with gastrointestinal problems.

Based on : Hojsak I et al. Benefits of dietary fibre for children in health and disease. Arch Dis Child 2022;107:973–979.*