Dietary intake of tyrosine and phenylalanine, and p-cresyl sulfate plasma levels in non-dialyzed patients with chronic kidney disease

Abstract

Background: Patients with chronic kidney disease (CKD) present an imbalance of the gut microbiota composition, leading to increased production of uremic toxins like p-cresyl sulfate (PCS), product from bacterial fermentation of the amino acids tyrosine (Tyr) and phenylalanine (Phe) from the diet. Thus, diet may be a determinant in the uremic toxins levels produced by the gut microbiota. The aim of this study was to evaluate the possible relationship between Tyr and Phe intake and PCS plasma levels in non-dialysis CKD patients. Methods: Twenty-seven non-dialysis CKD patients (stages 3 and 4) without previous nutritional intervention were evaluated. The dietary intake was evaluated using a 24-hour recall, 3-day food record and protein intake was also estimated by Protein Nitrogen Appearance (PNA). The plasma levels of PCS were measured using reverse phase high performance liquid chromatography. Results: The evaluated patients (GRF, 34.8 ± 12.4 mL/min, 54.2 ± 14.3 years, BMI, 29.3 ± 6.1 kg/m2) presented mean protein intake of 1.1 ± 0.5 g/kg/day), Tyr of 4.5 ± 2.4 g/day and Phe of 4.6 ± 2.5 g/day. PCS plasma levels (20.4 ± 15.5 mg/L) were elevated and positively associated with both, Tyr (r = 0.58, p = 0.002) and Phe intake (r = 0.53, p = 0.005), even after adjustments for eGFR and age. Conclusion: This study suggests that the diet is an important modulator of the uremic toxins plasma levels produced by the gut microbiota, in non-dialysis CKD patients.

Food-Derived Uremic Toxins in Chronic Kidney Disease

“…Similar to indoxyl sulfate, a modulation of the plasma retention of these metabolites may be possible via the diet and microbiome modifications. A recent study showed that higher tyrosine and phenylalanine content in diet contributes to p-cresyl sulfate plasma levels in non-dialyzed patients with CKD after correcting for GFR [ 140 ].…”

The Effect of Dietary Protein Concentration on the Fecal Microbiome and Serum Concentrations of Gut-Derived Uremic Toxins in Healthy Adult Cats

“…In addition, the amino acid concentrations of study diets could have impacted the potential magnitude of changes seen in serum concentrations during the study period. In non-dialyzed patients with CKD, a positive correlation was found between tyrosine and phenylalanine dietary intake and plasma pCS concentrations [ 32 ]. Oral choline supplementation in healthy people increases plasma TMAO concentrations within 1 month of supplementation [ 33 ].…”