Hemodialysis Decreases the Concentration of Accumulated Plant Phenols in the Plasma of Patients on Maintenance Dialysis: Influence of Residual Renal Function

Abstract

Plant phenols may accumulate in end-stage kidney disease. The effect of hemodialysis on their plasma concentration remains poorly determined. Contingent on concentration, health-promoting or noxious effects occur; therefore, we assessed plasma concentration in hemodialyzed patients. In total, 21 maintenance hemodialyzed patients with diuresis < 500 mL per day (with oliguria), nine hemodialyzed patients with diuresis ≥ 500 mL per day (without oliguria) and 31 healthy volunteers were included. Nine phenolic acids were identified with high-performance liquid chromatography and total polyphenol concentration was determined with the Folin-Ciocalteu method in pre- or post-hemodialysis plasma and pre- or intra-hemodialysis dialysate. The concentration of total polyphenols was 27% higher in pre-hemodialysis plasma than in that of controls (0.95 ± 0.18 mmol/L [P < 0.0001]). The concentration of total polyphenols was higher in patients with oliguria (1.01 ± 0.17) than in those without (0.84 ± 0.13 mmol/L), despite the former having more intense hemodialysis (Kt/V 1.29 ± 0.31 and 0.77 ± 0.25, respectively). Pre-hemodialysis phenolic acid concentration in patients undergoing dialysis exceeded reference values by 3 to 34 times (3-hydroxyphenylacetic acid and vanillic acid, respectively), from 0.69 (dihydrocaffeic acid) to 169.3 μmol/L (hippuric acid). The concentration of six phenolic acids (3-hydroxyhippuric, caffeic, dihydrocaffeic, hippuric, homovanillic, and vanillic acid) was 1.1 (homovanillic) to 11.3 (3-hydroxyhippuric) times higher in patients with oliguria than in those without. 4-hydroxyhippuric acid occurred more in the plasma of patients with oliguria than in those without oliguria. A single hemodialysis session decreased total polyphenol concentration by 16% and phenolic acids from 30% (caffeic) to 58% (vanillic and 3-hydroxyphenylacetic acid) and these compounds appeared in the dialysate. The percentage decrease (Δ%) of creatinine concentration correlated with the Δ% of total polyphenols and five phenolic acids (3-hydroxyphenylacetic, dihydrocaffeic, hippuric, homovanillic, and vanillic acid). Urea Δ% and Kt/V correlated only with the Δ% of homovanilic acid. The results demonstrate that phenols accumulate variably in hemodialyzed patients and are differently eliminated during hemodialysis. Residual renal function ensures a lower concentration of plasma phenols.

Pomegranate juice improves cardiometabolic risk factors, biomarkers of oxidative stress and inflammation in hemodialysis patients: a randomized crossover trial

“…Also, consumption of pomegranate before dialysis session may reduce its beneficial effect since pomegranate polyphenols pass through the dialysis membrane and are discarded in the dialysate. 36,37 Similarly, the lack of PJ effect on the total and LDL cholesterol in our study may be partly due to relatively normal levels of these lipids in the participants as other studies on diabetes patients with elevated blood lipids showed promising results. 38,39 The lipid-lowering and anti-atherogenic properties of pomegranate may be attributed to a number of mechanisms such as regulating the expression of the genes involved in lipogenesis and fatty acid oxidation in the liver 40 ; increasing the expression and activity of paraoxonase-1; the antioxidant enzyme in HDL particles which prevents LDL oxidation 41 ; and suppression of oxidized LDL degradation and of cholesterol synthesis in macrophages.…”

“…Some of the controversy over the results of different studies may be explained by the baseline values of triglycerides and HDL cholesterol which probably should be at unfavorable levels in order for pomegranate to exert its benefit. Also, consumption of pomegranate before dialysis session may reduce its beneficial effect since pomegranate polyphenols pass through the dialysis membrane and are discarded in the dialysate . Similarly, the lack of PJ effect on the total and LDL cholesterol in our study may be partly due to relatively normal levels of these lipids in the participants as other studies on diabetes patients with elevated blood lipids showed promising results .…”

Modulation of the Gut Microbiota by Resistant Starch as a Treatment of Chronic Kidney Diseases: Evidence of Efficacy and Mechanistic Insights

“…In vitro work has shown that phenylacetic acid increases ROS formation (227), impairs mitochondrial metabolism (228), and can directly inhibit renal tubular efflux pumps (229). Another microbial pathway for phenylalanine leads to the production of mtyramine, which undergoes further enzymatic conversion to 3-hydroxyphenylacetic acid (230), which is elevated in the plasma of hemodialysis patients (231). Presence of phenylacetic acid in plasma is dependent on the gut microbiota (156) and rats with adenine-induced CKD receiving an RSsupplemented diet had reductions in the concentration of 3hydroxyphenylacetic acid by 71% in cecal digesta and 64% in the serum (103), suggesting that targeting of the gut microbiota may prove a useful therapy.…”

Effects of pomegranate juice on cardiometabolic risk factors and biomarkers of oxidative stress and inflammation in hemodialysis patients, a crossover controlled trial

“…Some of the controversy over the results of different studies may be explained by baseline values of triglycerides and HDL cholesterol in participants which likely need to be in unfavorable levels in order for pomegranate to exert its benefit. Also, consumption of pomegranate before dialysis session may reduce its beneficial effect because pomegranate polyphenols pass through dialysis membrane and are discarded in the dialysate [32,33].…”