Reed P I, Johnston B J, Walters C L, Hill M J
Lady Sobell Gastrointestinal Unit, Wexham Park Hospital, Slough, Berks, UK.
IARC Sci Publ. 1991(105):139-42.
Ascorbic acid has been shown to decrease nitrosation in vivo, and epidemiological data suggest that the consumption of foods rich in this vitamin is associated with a reduced risk for gastric cancer. In order to study this suggestion further, fasting gastric juice samples were obtained from 62 high-risk patients (seven with atrophic gastritis, ten with pernicious anaemia, ten with partial gastrectomy, 21 with vagotomy and drainage and 14 with highly selective vagotomy), before, during four weeks' treatment with 1 g ascorbic acid four times daily, and four weeks after treatment. Samples were analysed for pH, total and nitrate-reducing bacterial counts, nitrite and N-nitroso compounds. Treatment with ascorbic acid lowered the median pH only in the vagotomized patients (p less than 0.001) but resulted in a reduction in median nitrate-reducing bacterial counts and in nitrite and N-nitroso compound concentrations in all groups, except for an increase in the nitrate-reducing bacterial count in atrophic gastritis patients and in nitrite in those with pernicious anaemia. These data suggest that treatment with a high dose of ascorbic acid reduces the intragastric formation of nitrite and N-nitroso compounds.
已证明维生素C可在体内减少亚硝化作用，并且流行病学数据表明，食用富含这种维生素的食物与降低患胃癌的风险相关。为了进一步研究这一观点，在62例高危患者（7例萎缩性胃炎、10例恶性贫血、10例部分胃切除术、21例迷走神经切断术和引流术以及14例高选择性迷走神经切断术）中，于每日4次服用1克维生素C进行四周治疗之前、治疗期间以及治疗四周后，获取空腹胃液样本。对样本进行pH值、总细菌计数和硝酸盐还原细菌计数、亚硝酸盐和N-亚硝基化合物分析。维生素C治疗仅使迷走神经切断术患者的pH值中位数降低（p<0.001），但导致所有组的硝酸盐还原细菌计数中位数以及亚硝酸盐和N-亚硝基化合物浓度降低，不过萎缩性胃炎患者的硝酸盐还原细菌计数增加，恶性贫血患者的亚硝酸盐增加。这些数据表明，高剂量维生素C治疗可减少胃内亚硝酸盐和N-亚硝基化合物的形成。
