> Could free radicals actually be part of the immune system?
Yes, it it already well-known that generation of free radicals is part of a normal immune response[1]. Basically, certain immune cells go into an inflamed area and start generating and releasing as many free radicals as they can in order to cause maximum damage. So if that particular immune mechanism is important in the body's response to cancer, then taking excessive antioxidants could plausibly impair the body's ability to fight cancer.
Yes, it it already well-known that generation of free radicals is part of a normal immune response[1]. Basically, certain immune cells go into an inflamed area and start generating and releasing as many free radicals as they can in order to cause maximum damage. So if that particular immune mechanism is important in the body's response to cancer, then taking excessive antioxidants could plausibly impair the body's ability to fight cancer.
[1] http://www.ncbi.nlm.nih.gov/pubmed/10807157