EFFECT OF FAT AND FIBER ON COLONIC INTESTINAL EPITHELIAL CELLS

这项研究考察了不同水平的膳食脂肪和纤维对结肠上皮细胞增殖和死亡的影响。受试者被给予良好控制的饮食(保持体重，代谢)，以脂肪/纤维组合(高、中、低脂肪和高、中、低纤维)为自变量。入院后，在基线内窥镜活检(通过柔性乙状结肠镜)后，受试者被安排低脂肪、高纤维饮食4周。使用内窥镜活检、血液和粪便样本评估结肠上皮、丁酸钠和Ki-ras癌基因突变。研究意义：结肠癌是人类常见的恶性肿瘤。研究表明，饮食中的脂肪和纤维会影响结直肠癌的发病率。与摄入较少脂肪和较多纤维的人群相比，食用高脂肪和低纤维饮食的人群总体上有更高的结直肠癌发病率。目前尚不完全清楚膳食脂肪和纤维是否是结肠癌发生的独立变量。丁酸钠是一种短链脂肪酸，在结肠细菌发酵膳食纤维时，会在结肠中大量产生。丁酸钠在体外可抑制培养的结肠癌细胞的增殖并诱导其凋亡。

This research examines the effect of different levels of dietary fat and fiber on the proliferation and death of colonic epithelial cells. Subjects are given a well-controlled diet (weight maintaining, metabolic), with fat/fiber combination (high, normal or low fat and high, normal or low fiber) as the independent variable. Upon admission, after baseline endoscopic biopsy (by flexible sigmoidoscopy), subjects are placed on a low fat, high fiber diet for 4 wks. Assessment of colonic epithelium, sodium butyrate, and Ki-ras oncogene mutations are performed using endoscopic biopsy, blood, and stool samples. SIGNIFICANCE OF STUDY: Colon cancer is a common human malignancy. Dietary fat and fiber have been shown to affect the incidence of colorectal cancer. Populations consuming diets high in fat and low in fiber overall have greater incidence rates of colorectal cancer, compared to populations consuming less fat and more fiber. It is not entirely clear whether dietary fat and fiber are independent variables with respect to colon carcinogenesis. Sodium butyrate, a short chain fatty acid, is generated in the colon in large quantities as dietary fiber is fermented by colonic bacteria. Sodium butyrate, in vitro, reduces the proliferation and induces apoptosis in cultured colon cancer cells.