Time course of plasma glutathione (GSH) (A) and oxidized GSH (GSSG) (B) and their ratio (C) in older adults after acute intake of skim milk vehicle (C) and 450 (H) mg GAE ASP. The data are presented as the percent change from the respective baseline (0 h). Baseline values of GSH, GSSH, and their ratio were 1.16 ± 0.14, 0.11 ± 0.01 µmol/L, and 12.1 ± 2.4, respectively. Values are expressed as mean ± SEM, n = 7. Means not sharing the same letter at the same time point are significantly different, p ≤ 0.05, tested using PROC GLM, followed by Tukey’s HSD multi-comparison test. p-values of the dose effect for GSH, GSSG, and their ratio were 0.029, 0.013, and 0.014, respectively.