Dietary fibre intake is low in paediatric chronic kidney disease patients but its impact on levels of gut-derived uraemic toxins remains uncertain.

BACKGROUND: Chronic kidney disease (CKD) in children is a pro-inflammatory condition leading to a high morbidity and mortality. Accumulation of organic metabolic waste products, coined as uraemic toxins, parallels kidney function decline. Several of these uraemic toxins are protein-bound (PBUT) and gut-derived. Gut dysbiosis is a hallmark of CKD, resulting in a state of increased proteolytic fermentation that might be counteracted by dietary fibre. Data on fibre intake in children with CKD are lacking. We aimed to assess dietary fibre intake in a paediatric CKD cohort and define its relationship with PBUT concentrations. METHODS: In this multi-centre, cross-sectional observational study, 61 non-dialysis CKD patients (9 ± 5 years) were included. Dietary fibre intake was assessed through the use of 24-h recalls or 3-day food records and coupled to total and free levels of 4 PBUTs (indoxyl sulfate (IxS), p-cresyl sulfate (pCS), p-cresyl glucuronide (pCG) and indole acetic acid (IAA). RESULTS: In general, fibre intake was low, especially in advanced CKD: 10 ± 6 g/day/BSA in CKD 4-5 versus 14 ± 7 in CKD 1-3 (p = 0.017). Lower concentrations of both total (p = 0.036) and free (p = 0.036) pCG were observed in the group with highest fibre intake, independent of kidney function. CONCLUSIONS: Fibre intake in paediatric CKD is low and is even worse in advanced CKD stages. Current dietary fibre recommendations for healthy children are not being achieved. Dietary management of CKD is complex in which too restrictive diets carry the risk of nutritional deficiencies. The relation of fibre intake with PBUTs remains unclear and needs further investigation. Graphical abstract.