Thoughts on Antioxidants and Autophagy
Eric Drexler writes on the topic of antioxidants and autophagy: "Autophagy removes cell components - including ROS-damaged proteins and organelles - by engulfing and digesting them, producing wastes and recycled nutrients. ... Upregulating autophagy [has] extraordinarily wide-ranging benefits. Interventions that extend healthy lifespan in animal models include calorie restriction, resveratrol, spermidine, and rapamycin, and in each operates, at least in part, through autophagy. Upregulating autophagy has positive effects in models of several specific neurodegenerative diseases, too ... antioxidants inhibit basal autophagy and block the induction of autophagy by calorie restriction and other means. Because this effect inhibits the central mechanism of cell repair, it helps explain why dietary antioxidants have failed to deliver their expected benefits to health and longevity." I would have said it has more to do with failing to target mitochondria, given the benefits demonstrated by mitochondrially targeted antioxidants. As Drexler notes, however, there's research to back up the antioxidant-autophagy link, which may have some relation to earlier research showing antioxidant supplementation to interfere with the processes of hormesis, and thus block beneficial effects of mild stress such as exercise.
Link: http://metamodern.com/2010/09/26/antioxidants-block-cell-repair/