It generates "massive" amounts of free radicals.
So does exercise.
OMG! is it really??
Everything we do harming us then, I mean what the hell?
Can you point a single thing that does not harm at all?
My point was that just because it does something that is "bad" on face value, that doesn't mean that it doesn't benefit us. Exercise generates free radicals, lots and lots and lots of them. This damages mitochondrial DNA, and by chain reactions it can have a minimal effect on nuclear DNA as well. These are bad things.
On the other hand, the stress to the mitochondria helps kick in the cells' natural autophagy system, which gobbles up the most damaged mitochondria, and the relatively healthier ones that survive go through a process of replications to replace the damaged ones.
Also, the damage causes the cells' to increase production of antioxidant enzymes and ship them to where they do the most good: inside the mitochondria. You can't get that benefit from supplements or nutrition.
Also, exercise helps tune your mitochondria, so they produce less free radicals for the 23 hours a day that you're not exercising.
And of course, let's not forget that exercise improves cardiovascular health and muscle health and bone health, especially if it's rigorous and involves a decent amount of resistance.
All in all, for whatever damage exercise causes, you get a fairly substantial net benefit. Just use moderation. Three hours of exercise per day, seven days a week, is most likely going to shorten your life. Half an hour to an hour a day, three or four days a week, will most likely extend your life. Moderation is the key.
The same is true for red wine. We know that binging is bad for your health, but we know that the French live 3 to 5 years longer than Americans, after controlling for smoking, exercise, diet, and obesity (and probably other things as well). Red wine seems to be a major factor, in moderation, of course.