Blood glutathione. Effect of red wine consumption on blood GSH concentrations from young (18–30 yrs) and older (≥ 50 yrs) volunteers. Bars represent mean ± SEM of blood GSH values pre and post two weeks of red wine consumption or abstinence. YA, young abstinence; YW, young wine; OA, older abstinence; OW older wine. a indicates a significant change with wine P < 0.05. b indicates a significant difference between young and old, P < 0.05.