ASCORBIC-ACID AND TOTAL VITAMIN-C CONCENTRATIONS IN PLASMA, GASTRIC-JUICE, AND GASTROINTESTINAL MUCOSA - EFFECTS OF GASTRITIS AND ORAL SUPPLEMENTATION

Epidemiological evidence suggests that high dietary ascorbic acid redu ces gastric cancer risk. It may do this by either reducing N-nitroso c ompound formation in gastric juice, or by scavenging reactive oxygen s pecies in gastric mucosa. The aim of this study was to discover if pot ential ascorbic acid protection might be increased by supplementation. Thirty two patients were supplemented with ascorbic acid, 500 mg twic e daily for two weeks. Gastric juice, plasma, and upper gastrointestin al biopsy ascorbate concentrations were measured and compared with val ues in 48 unsupplemented patients. It was found that ascorbic acid and total vitamin C concentrations were considerably higher in biopsy spe cimens from oesophagus, body, antrum, duodenum, and rectum, compared w ith values in plasma or gastric juice. Plasma and mucosal concentratio ns were unaffected by the presence of chronic gastritis but gastric ju ice concentrations were substantially lower in patients with chronic g astritis than in patients with normal histological assessment (p<0.01) . Patients receiving ascorbic acid supplements had higher ascorbic aci d concentrations in plasma (p<0.001), gastric juice (p<0.001), and at all biopsy sites in the upper gastrointestinal tract (p<0.05). Gastric juice ascorbic acid and total vitamin C concentrations in gastritic p atients, however, were still less after supplementation than in normal subjects (p<0.01). These data suggest that high ascorbic acid intake could reduce gastric cancer risk, but its protective effect might be g reater if gastritis is treated (for example, by Helicobacter pylori er adication).