Robert F. Cathcart, M.D. :ABSTRACT Bowel tolerance to orally ingested ascorbic acid increases with the toxicity of diseases. Bowel tolerance with a disease such as mononucleosis may reach 200 or more grams per 24 hours without it producing diarrhea. A marked clinical amelioration or cure is achieved in many disease processes when threshold doses near bowel tolerance are given. In a sense, it is the reducing equivalents carried by free radical scavengers that quench free radicals, not the free radical scavengers themselves.