Via transhumantech, some pointers from researcher Joao Magalhaes on longevity and damaging reactive oxygen species (ROS, including the much maligned free radicals). Read the whole thing, but here's the bottom line from his point of view:
This seems to support the idea that ROS are not just damaging compounds, but essential biological molecules used in a myriad of functions. On this subject, I have a paper on ROS that could be of interest to some of you.
Lastly, here's another recent paper showing that antioxidant protection does not correlate with longevity in rodents, in line with many other results suggesting that antioxidant protection is already optimized in mammals.
In other words, attempts to improve human longevity through manipulation of antioxidant protection may not be such a great use of resources, but this is still a very complex area of study - like all biology - and not a settled answer yet.