A study in Denmark showed that increasing fruit and vegetable intake did not significantly change oxidative stress parameters.

“there's one study done in Denmark where they increased the amount of fruits and vegetables in the participants diet for I believe it was six weeks and they went from I think one or two servings and fruits and vegetables per week to six to eight to ten vegetables servings of fruits and vegetables per week a massive increase the amount of vitamin C in their diet increased from 70 to 270 milligrams per week and the amount of vegetables increased 10 to 12 fold no change in the oxidative stress parameters no improvement in the oxidative stress parameters”