Great article here from Peak Performance Online pertaining to the production of free radicals related to exercise and dietary influence.
"....it makes sense to ensure that your diet is high in antioxidants".
the case for olive oil-
"The authors concluded that diets with olive oil as the unique fat source are able to produce membranes whose features allow them to be more resistant to lipid peroxidation even if the overall cell metabolism is increased (Life Sciences, 1992, ibid). This outcome has not been confirmed for human subjects, but the circumstantial evidence is fairly strong. It has been shown that free radical production increases during intensive sporting practice (Europeam Journal of pplied Physiology, volS6 pp313-6). It's also been demonstrated that people' s cell membranes reflect their dietary fat intake.
What does this mean in practical terms? To change the ratio of polyunsaturates to monounsaturates in your diet, the most significant thing you can do is to use olive oil in preference to a polyunsaturated oil (such as sunflower, corn, blended vegetable oils). It' s also possible to buy dairy-type spreads based on olive oil. Avocados are rich in monounsaturates, as are some nuts, including hazelnuts, cashews, and almonds."