The role of antioxidants in gastric carcinogenesis

The epidemiologic evidence for a role of antioxidants in inhibiting carcinogenesis in humans is briefly summarized. Mechanistic pathways of protection by antioxidants are illustrated with the prevailing model of gastric carcinogenesis in humans. In this model, ascorbic acid may be involved at the early stage of chronic gastritis; its secretion into the stomach is inhibited by infection with Helicobacter pylori, a major cause of gastritis. Ascorbic acid may also play a role in blocking the nitrosation of amines and related compounds in the gastric microenvironment. Carotenoids are also involved in the chain of gastric cancer causation and apparently play an important role in preventing mutations in the advanced stages of the process. The gastric cancer model supports the notion that invasive cancer is the result of insufficient control of oxidative stress applied to replicating cells over a prolonged period of time.