User blog comment:PlantyThePottedPlant/Random Topic Blogging III: Blog Harder/@comment-1659929-20140724153103/@comment-4121682-20140725033007

And when typing in "polycystic ovary syndrome oxidative stress" on PudMed.gov, I got 123 results. Considering that every chronic disease is increasingly becoming known to be caused by oxidative stress, it makes complete sense.

In all seriousness, go to PubMed.gov, list any chronic disease (noninfectious; something that you don't "catch", but are born with or develop) you know of, type in "oxidative stress", and see how many results you'll get. This is all peer-reviewed research, so each piece of research literature there has been through 2 or more organizations who scrutinize it (try to disprove it or look for flaws) before it even gets published in medical journals.