Waring A J, Drake I M, Schorah C J, White K L, Lynch D A, Axon A T, Dixon M F
Centre for Digestive Diseases, General Infirmary at Leeds, University of Leeds.
Gut. 1996 Feb;38(2):171-6. doi: 10.1136/gut.38.2.171.
Epidemiological evidence suggests that high dietary ascorbic acid reduces gastric cancer risk. It may do this by either reducing N-nitroso compound formation in gastric juice, or by scavenging reactive oxygen species in gastric mucosa. The aim of this study was to discover if potential ascorbic acid protection might be increased by supplementation. Thirty two patients were supplemented with ascorbic acid, 500 mg twice daily for two weeks. Gastric juice, plasma, and upper gastrointestinal biopsy ascorbate concentrations were measured and compared with values in 48 unsupplemented patients. It was found that ascorbic acid and total vitamin C concentrations were considerably higher in biopsy specimens from oesophagus, body, antrum, duodenum, and rectum, compared with values in plasma or gastric juice. Plasma and mucosal concentrations were unaffected by the presence of chronic gastritis but gastric juice concentrations were substantially lower in patients with chronic gastritis than in patients with normal histological assessment (p < 0.01). Patients receiving ascorbic acid supplements had higher ascorbic acid 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 patients, 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 greater if gastritis is treated (for example, by Helicobacter pylori eradication).
流行病学证据表明，高膳食抗坏血酸可降低胃癌风险。其可能通过减少胃液中N-亚硝基化合物的形成，或通过清除胃黏膜中的活性氧来实现。本研究的目的是探究补充抗坏血酸是否可能增强其潜在的保护作用。32例患者补充抗坏血酸，每日两次，每次500毫克，持续两周。测量胃液、血浆和上消化道活检组织中的抗坏血酸浓度，并与48例未补充抗坏血酸的患者的值进行比较。结果发现，与血浆或胃液中的值相比，食管、胃体、胃窦、十二指肠和直肠活检标本中的抗坏血酸和总维生素C浓度显著更高。血浆和黏膜浓度不受慢性胃炎的影响，但慢性胃炎患者的胃液浓度显著低于组织学评估正常的患者（p<0.01）。接受抗坏血酸补充剂的患者血浆（p<0.001）、胃液（p<0.001）以及上消化道所有活检部位的抗坏血酸浓度均较高（p<0.05）。然而，胃炎患者补充抗坏血酸后，胃液中的抗坏血酸和总维生素C浓度仍低于正常受试者（p<0.01）。这些数据表明，高抗坏血酸摄入量可降低胃癌风险，但如果治疗胃炎（例如，通过根除幽门螺杆菌），其保护作用可能会更大。
