Nature in her infinite wisdom is an avid recycler. First, body processes or elements that Science thinks are negative and might cause disease (Free Radicals, Oxidative Stress), Nature has over the years developed ways 
to harness some of this radical energy for vitally needed positive body functions. ref (ROS are radicals) Very few if any body processes are only negative, especially LDL "the BAD" cholesterol. Well, maybe cell senescence (aging). NO, not even cell aging is negative, check out this one, too. ref To limit damage from these potentially destructive radical elements, Nature puts strict controls and limits in place to monitor their activity and concentrations, whether performing needed functions or unwanted consequences. General >ref
One of the down falls of Mainstream Medicine is a failure to appreciate this natural wisdom in body functions using otherwise negative aspects for positive outcomes. EXAMPLE: During the common cold, the body uses cold symptoms as healing tools. Fever burns and kills the viruses while sneezing and coughing expel them out of the body. Many cold medicines are designed to block these healing activities, while they really need more control and direction.Of course these activities can get out of control and reach levels where they are damaging, so prudent monitoring and appropriate use of cold medicine is needed, BUT, a marriage of nature and medicine is needed to maximize healing processes.
EXAMPLE: Vitamins C and E are avid anti-oxidants, meaning they sacrifice themselves by giving up part of their structure to neutralize free radicals. Nature knew these two nutrients were too valuable to loose so quickly, so along comes Alpha Lipoic Acid to regenerate the broken parts of vitamins C and E making them whole again able to perform more vital body functions.
EXAMPLE: Antioxidants in excess work too well in neutralizing radicals. Some radicals have positive functions to perform before they are destroyed. Free radicals such as Reactive Oxygen Species are used by the body to destroy unwanted cells, such as DNA damaged or pre-cancerous cells. These nasty Radicals are perfect for these functions but definitely have to be closely watched to keep them under control. There is also an insulin glucose cell uptake process that is initiated by free radicals.