Postgraduate Program in Nutrition, Federal University of Santa Catarina, Florianópolis, SC, Brazil.
Department of Pharmacy, Federal University of Santa Catarina, Florianópolis, SC, Brazil.
Int Urol Nephrol. 2021 Aug;53(8):1695-1704. doi: 10.1007/s11255-021-02797-8. Epub 2021 Apr 27.
Whey protein has antioxidant properties through its amino acid cysteine, which enhances the biosynthesis of glutathione, the most abundant antioxidant non-protein in mammalians. Glutathione influences vitamin C recycling and increases its protective effect on oxidative stress (OS). The aim of this study was to analyse the effect of whey protein and vitamin C supplementation on OS biomarkers in chronic haemodialysis (HD) patients.
This pioneer trial was a randomised, double-blind, pilot study in patients from a dialysis clinic. Patients were randomised into three groups (1:1:1) and stratified by HD frequency (2 or 3 times/week). Sachets containing protein powder (20.0 g) with/without vitamin C (0.25 g) or placebo (20.0 g of white rice flour) with vitamin C (0.25 g) were supplemented after each HD session, 3 times/week for 8 weeks. Blood samples were collected at the baseline period and after 8 weeks for the measurement of reduced glutathione (GSH), oxidised glutathione (GSSG), the GSH:GSSG ratio, malondialdehyde, vitamin C, and glutathione peroxidase-1.
Twenty-two patients were enrolled, of which 18 concluded the trial, 6 per group (18.2%, n = 4 losses during follow-up). The vitamin C group presented decreased GSH levels after supplementation (p = 0.053) and a decreasing tendency in the GSH:GSSG ratio (non-statistically significant), while MDA levels significantly decreased only in the whey protein-supplemented groups (p ≤ 0.05).
The results suggest a pro-oxidant effect of 0.25 g of vitamin C alone in chronic HD patients.
https://ensaiosclinicos.gov.br/ , RBR-65b8f4.
乳清蛋白通过其氨基酸半胱氨酸具有抗氧化特性，可增强哺乳动物中最丰富的非蛋白抗氧化剂谷胱甘肽的生物合成。谷胱甘肽影响维生素 C 的循环利用，并增加其对氧化应激 (OS) 的保护作用。本研究旨在分析乳清蛋白和维生素 C 补充对慢性血液透析 (HD) 患者 OS 生物标志物的影响。
这是一项在透析诊所的患者中进行的随机、双盲、试点研究。患者被随机分为三组（1:1:1），并按 HD 频率（每周 2 或 3 次）分层。在每次 HD 治疗后，补充含有蛋白粉（20.0 g）和/或维生素 C（0.25 g）或不含维生素 C 的安慰剂（20.0 g 白米粉）的小袋，每周 3 次，持续 8 周。在基线期和 8 周后采集血样，用于测量还原型谷胱甘肽 (GSH)、氧化型谷胱甘肽 (GSSG)、GSH:GSSG 比值、丙二醛、维生素 C 和谷胱甘肽过氧化物酶-1。
共纳入 22 例患者，其中 18 例完成试验，每组 6 例（18.2%，n=4 例在随访期间丢失）。补充维生素 C 后，维生素 C 组 GSH 水平下降（p=0.053），GSH:GSSG 比值呈下降趋势（无统计学意义），而仅在补充乳清蛋白的组中 MDA 水平显著下降（p≤0.05）。
结果提示单独补充 0.25 g 维生素 C 对慢性 HD 患者具有促氧化作用。
https://ensaiosclinicos.gov.br/ ，RBR-65b8f4。
