The associations between nutrition and circulating gut microbiota-derived uremic toxins in patients undergoing kidney...

Gut microbiota generates a series of bioactive metabolites that can be converted into uremic toxins such as trimethylamine-N-oxide (TMAO), p-cresyl sulfate (pCS), and indoxyl sulfate (IS). The aim of the study was to examine the association between diet and the concentrations of the mentioned gut microbiota-derived uremic toxins.

An observational cross-sectional study was conducted involving 210 participants: 84 hemodialysis (HD) patients, 44 peritoneal dialysis (PD) patients, 52 kidney transplant recipients (KTR), and 30 healthy controls. Dietary intake was assessed using a 3-day food diary and a food frequency questionnaire with 6 answers (FFQ-6). The alternate Mediterranean diet (aMED) score was calculated based on data obtained from the 3-day food diary and FFQ-6. Blood samples were analyzed for TMAO, pCS, and IS concentrations using liquid chromatography-mass spectrometry (LC-MS/MS).

Significant differences in TMAO, pCS, and IS concentrations were observed among the study groups. HD and PD patients exhibited higher levels of these metabolites compared to KTR and healthy controls. The median aMED score was 4 (3-5) points in the HD group, 4.5 (4-6) points in the PD group, 5 (4-6) points in the KTRs, and 6 (5-7) points in the control group. Higher adherence to the Mediterranean diet (aMED score) was associated with lower pCS levels in dialysis patients. Vegetable intake several times a day was found to mitigate the effects of phenylalanine and tyrosine intake on pCS concentration among dialysis patients.

The diet of patients undergoing kidney replacement therapy (KRT) significantly affects the concentrations of gut microbiota-derived uremic toxins. These findings highlight the importance of dietary management in mitigating the adverse effects of these toxins in patients with chronic kidney disease (CKD).