These are some general things I've been thinking lately, and I thought to share them for wider scrutiny, even at this early stage.
It seems that when it comes to anti/pro-oxidant behaviour, most antioxidants follow a U-shaped curve: In lower concentrations the anti-oxidants scavenge ROS and reduce oxidative stress - but in higher concentrations, the breakdown of antioxidants leads into greater oxidative stress. This seems to be true for most antioxidants: Vitamin C, reservatrol, plant polyphenols etc. On the other hand, the reason why plant polyphenols etc. can be beneficial, is exactly the oxidative stress - the temporary oxidative stress leads into upregulation of cellular redox system, which lowers the long-term oxidative stress.
So, I'm wondering, what does this mean when it comes to antioxidant dosage? It seems to become an optimization game: minimize oxidative stress in general, while maximizing hormetic response with optimal stress-to-hormesis 'pulses'. So, if you want both the antioxidant and hormetic benefits, it seems that you should ingest a small daily dosage of antioxidants, that optimally reduce the general level of oxidative stress, and you should occasionally take a larger amount, which stresses your system and leads to hormesis. When looking at research, I'm having difficulty of locating any studies where antioxidants have been studied in such cyclic manner, though. Most studies have noted that antioxidants don't affect the lifespan - but then again, I suppose most studies use high doses of antioxidants ingested every day, which would mean that there might be so much daily stress that counter-acts any benefits.
If 'antioxidant cycling' is a thing, it could also be one reason why 'varied diet rich with veggies and fruit' seems to be healthy: if you eat different foods rich with different vitamins, polyphenols etc. on different days, so you get temporary hormetic stress of different kind, but not every day.
In my mind, I'm comparing antioxidants to other behaviour that we know causes hormetic responses: exercise. Cardio-style exercise has wide range of benefits, reducing risk of most diseases and reducing mortality up to 50%(!) - and most of these come from hormetic responses to a repeated short period of stress. From exercise studies, we know that there is also a U-shaped curve when it comes to reducing risk of mortality. Optimal response seems to be induced by something like 30-90 minutes of moderate exercise repeated a few times per week, so roughly speaking "1h of moderate stress every other day". With huge exercise amounts, the benefits diminish towards non-exerciser's levels. Similar thing might be true for antioxidant intake; maybe antioxidants are better every other day or so.
Then again, I have no idea how exercise-induced hormesis and different amounts of antioxidants mix, or how does the hormetic response differ when it comes to exercise or diet-based source.
Thoughts?