So besides oxidative stress, there's a new term coming up now: "antioxidative stress"
I.e. too much antioxidants, especially the amounts you can get from supplements, are not really helping you and are very likely counterproductive in the long term. Which makes a lot of sense, we didn't have such supplements available until a few decades ago, so we're exactly adapted to the amounts we get from foods.
Recent study in support of this:
http://www.hindawi.com/journals/oximed/2012/480895/
Oxidative stress arises when there is a marked imbalance between the production and removal of reactive oxygen species (ROS) in favor of the prooxidant balance, leading to potential oxidative damage. ROSs were considered traditionally to be only a toxic byproduct of aerobic metabolism. However, recently, it has become apparent that ROS might control many different physiological processes such as induction of stress response, pathogen defense, and systemic signaling. Thus, the imbalance of the increased antioxidant potential, the so-called antioxidative stress, should be as dangerous as well. Here, we synthesize increasing evidence on “antioxidative stress-induced” beneficial versus harmful roles on health, disease, and aging processes. Oxidative stress is not necessarily an un-wanted situation, since its consequences may be beneficial for many physiological reactions in cells. On the other hand, there are potentially harmful effects of “antioxidative stress,” especially in the cases of overconsumption of synthetic antioxidants. Antioxidants can neutralize ROS and decrease oxidative stress; however, this is not always beneficial in regard to disease formation or progression (of, e.g., cancer) or for delaying aging.
When it comes to stress
* small amounts are very much beneficial as then you can adapt to withstand more stress much better. E.g. you start with tiny amounts of raw egg yolks, which challenges the immune system, but slowly the immune system strengthens and you can eat 10-20 with no problem. I believe this holds for
any of the stressors that panacea has listed in the beginning.
* large amounts once in a while are usually devastating and should be avoided. Like running a marathon when you've never run more than 1km before.
The conclusion: try to have small amounts of various stresses, in some increasing progression if possible so that you build your resistance stronger and stronger over time, but avoid over-stressing at all costs.