EFFECTS OF DIETARY POLYUNSATURATED FAT ON HELICOBACTER PYLORI

幽门螺杆菌（H.幽门螺杆菌）感染是人类慢性胃炎的最常见原因，并且它已被认为是消化性溃疡疾病发展的致病因素。 近年来，流行病学研究表明，H。pylori是胃癌的独立危险因素，H.幽门螺杆菌感染者比未感染者发生这种病症的风险高3-6倍。从H.幽门相关性浅表性胃炎到伴有肠上皮化生的萎缩性胃炎被认为是胃癌发展的前兆。 研究者推测，H.幽门相关性慢性胃炎是萎缩性胃炎，可因饮食因素而延长或缩短。 富含水果和蔬菜以及低淀粉和盐的饮食与胃癌风险降低有关。 这些饮食中抗氧化剂的存在被认为是降低癌症风险的因素。这些饮食也富含多不饱和脂肪，与饱和脂肪酸相反，多不饱和脂肪酸已被证明能抑制细菌生长。 最近的研究证实多不饱和帽能抑制H。幽门螺杆菌（世界卫生组织将其命名为I类致癌物，估计胃癌的归因风险为50-60%）体外生长。 因此，抑制细菌生长的试剂，即，多不饱和脂肪可能会降低这种致癌物质导致的癌症风险。 该项目的研究人员假设，多水果和蔬菜的饮食可以保护胃癌，因为多不饱和脂肪的细菌静态特性。由于维生素E等抗氧化剂存在于富含多不饱和脂肪的油中，他们认为它们主要作为摄入这些脂肪的标志物，而不是预防胃癌的主要药物。 这项资助计划在一项横断面研究中记录多不饱和脂肪摄入与胃细菌负荷之间的间接相关性。 将进行体外研究，以阐明多不饱和脂肪不仅抑制生长，而且抑制该细菌粘附于人胃上皮细胞诱导的细胞毒性的程度。 证实这一假说对于世界上胃癌高发地区是非常重要的，因为这些地区既有高的H。幽门螺杆菌和高的再感染率与此有机体后，成功的抗生素治疗。从饮食中摄入富含多不饱和脂肪的食物会降低胃癌风险，这一知识可能是预防胃癌的一种具有成本效益的方法，因为在某些国家，已有疫苗可供使用，而抗生素治疗并不实用。

Helicobacter pylori (H. pylori) infection is the most common cause of chronic gastritis in man, and it has been implicated as an etiological factor in the development of peptic ulcer disease. More recently, epidemiological studies have demonstrated that H. pylori is an independent risk factor for gastric cancer and that people infected with H. pylori have a 3-6 fold higher risk of developing this condition than non-infected persons. Progression from H. pylori-related superficial gastritis to atrophic gastritis with intestinal metaplasia is felt to be a precursor to gastric cancer development. Investigators have postulated that the natural progression of H. pylori-associated chronic gastritis is to atrophic gastritis, which may be prolonged or shortened by dietary factors. Diets rich in fruits and vegetables and low in starch and salt are associated with a decreased risk of gastric cancer. The presence of antioxidants in these diets has been postulated to be the factors responsible for the decrease in cancer risk. These diets are also high in polyunsaturated fat which, as opposed to saturated ft, has been shown to inhibit bacterial growth. Recent studies have confirmed that polyunsatuated hat will inhibit H. pylori (named as a Class I carcinogen with an estimated attributable risk of 50-60% for gastric cancer by the World Health Organization) growth in vitro. Therefore, agents which inhibit bacterial growth, i.e., polyunsaturated fats are likely to decrease the risk of cancer due to this carcinogen. Investigators for this project postulate that diets high in fruits and vegetables protect gastric cancer because of the bacterial static properties of polyunsaturated fats. Since antioxidants such as vitamin E are present in oils rich in polyunsaturated fat, they feel that they serve mainly as a marker for ingestion of these fats, and are not the primary agents protecting against gastric cancer. This grant proposes to document in a cross-sectional study, the indirect correlation between polyunsaturated fat ingestion and gastric bacterial load. In vitro studies will be performed to elucidate the extent to which polynsaturated fat will not only inhibit growth, but also inhibit cytotoxicity induced by adherence of this bacterium to human gastric epithelial cells. Confirming this hypothesis would be very important to areas of the world which have a high incidence of gastric cancer, since these areas have both a high incidence of H. pylori and a high rate of re-infection with this organism after successful antibiotic treatment. Knowledge that dietary intake rich in polyunsaturated fat will reduce gastric cancer risk is likely to be a cost-effective way of preventing this disease, since there is a vaccine available and antibiotic therapy is not practical in certain countries.