Fiber Supplementation Lowers Plasma p-Cresol in Chronic Kidney Disease Patients

Abstract

Objective To determine the effects of supplemental fiber on plasma p-cresol, stool frequency, and quality of life (QoL) in chronic kidney disease (CKD) patients. Design and Setting In a 12-week single-blind study, participants were provided with control muffins and supplements (5.5 g sucrose/day) for 2 weeks, muffins containing 10 g/day pea hull fiber and control supplements for 4 weeks, and muffins with 10 g/day pea hull fiber and 15 g/day inulin as a supplement for 6 weeks. Subjects Individuals with CKD (n = 13; 6 males, 7 females; aged 65 ± 3 years; estimated glomerular filtration rate <50 mL/minute/1.732) completed the study. Main Outcome Measures Plasma p-cresol was determined by gas chromatography-mass spectrometry, stool frequency by 5-day journals, and QoL by the KDQOL-36™. Results Plasma p-cresol decreased from 7.25 ± 1.74 mg/L during week 1 to 5.82 ± 1.72 mg/L during week 12 (P < .05), and in participants with high compliance (>70% inulin intake), from 6.71 ± 1.98 mg/L to 4.22 ± 1.16 mg/L (P < .05). Total fiber intake increased from 16.6 ± 1.7 g/day during control to 26.5 ± 2.4 g/day (P < .0001) with the added pea hull and to 34.5 ± 2.2 g/day with pea hull and inulin (P < .0001). Stool frequency increased from 1.4 ± 0.2 stools/day during control to 1.9 ± 0.3 stools/day during both fiber periods (P < .05). No change in overall QoL was observed. Conclusions Supplementing the diet of CKD patients with fiber may be a dietary therapy to reduce p-cresol and improve stool frequency.

Pea Hull Fiber: A Dietary Fiber to Modulate Gastrointestinal Function and Gut Microbiota

“…In each of these studies, the acceptance of foods with added pea hull fiber was demonstrated by compliance. In the study with children, compliance with consumption of the snacks with added pea hull fiber was 77% versus 74% for the control snacks (18), whereas in the CKD study compliance with consumption of the muffins with added pea hull fiber was 92% versus 97% for the control muffins (42). In the long-term care study, no change in food intake was reported with the pea hull fiber intervention, suggesting the added pea hull fiber was acceptable (9).…”

“…However, inulin has not been shown to affect stool frequency in similarly sized trials (4,45), and thus, pea hull fiber, which is high in insoluble fiber, may have exerted this effect. In a small trial of adults with CKD, providing 1 muffin containing 10 g of pea hull fiber per day resulted in a significant increase in stool frequency (42). It is notable that when 15 g of inulin was provided as a supplement in addition to the pea hull fiber, no further increase in stool frequency was observed.…”

Stirring the Pot: Can Dietary Modification Alleviate the Burden of CKD?

“…Such epidemiological data should be interpreted with caution, however, as there is some uncertainty about whether dietary fibre per se is beneficial or whether other nutrients, including antioxidant compounds that are present in fibre-rich foods, act in a beneficial manner [52]. Interventions that have focused on increasing total dietary fibre intake in patients with pre-dialysis CKD have reported reductions in serum creatinine levels [53] and plasma p-cresol [54]. A four-week study in which patients with chronic renal failure consumed 50 grams per day of acacia gum, a highly fermentable fibre, led to a mean reduction in plasma urea of 12% [55].…”

The cross-talk between the kidney and the gut: implications for chronic kidney disease

“…However, to date, no clinical trial has evaluated the association between changes in the microbiota and the decrease in colonderived uremic toxins after prebiotic therapy in CKD. The few short-term prebiotic interventions performed so far have reported mixed effects on PCS and IS [131,[135][136][137][138]. The reasons for the heterogeneity in the results may be related to differences in type and amount of prebiotic used, factors that might be relevant for modulation of serum PCS and/or IS in CKD (Table 1).…”