Takeshita M, Ueda H, Shirabe K, Higuchi Y, Yoshida S
Department of Biochemistry, Oita Medical University School of Medicine, Hasama-machi, Japan.
Cancer. 1997 Apr 15;79(8):1487-93. doi: 10.1002/(sici)1097-0142(19970415)79:8<1487::aid-cncr7>3.0.co;2-8.
The nonpromoting effect of olive oil on colon carcinogenesis has been attributed to its high oleic acid content, whereas a positive association of monounsaturated fat in beef tallow with colon tumors has been reported. The effect of constituents other than fatty acids could not be neglected in these experiments. In order to minimize the effects of minor constituents in the oils, the authors compared conventional safflower oil with oil from a mutant strain of safflower that is rich in oleic acid.
ICR mice were treated with 1,2-dimethylhydrazine (DMH, 20 mg/kg body weight every week for 12 weeks) and then were fed either a high-fat diet (23.5% by weight), containing safflower oil (HF-LA) or high-oleic safflower oil (HF-OA), or a low-fat diet (5% by weight), containing safflower oil (LF-LA) or high-oleic safflower oil (LF-OA). The test diets were continued until termination of the experiment at 30 weeks after the first administration of DMH. Fatty acid composition of colon phospholipids was determined by gas-liquid chromatography-mass spectrometry.
Tumor multiplicity in animals fed the HF-OA diet was indistinguishable from that in animals fed LF-LA or LF-OA. In contrast, animals fed the HF-LA diet had a significantly higher incidence of colon tumors (mostly adenocarcinomas) than the other groups. Fatty acid profiles of colon phospholipids reflected those of the diet. Animals fed a HF-LA diet showed a marked decrease of nervonic acid (C24:1, n-9) in the colon sphingomyelin.
These data indicate that oleic acid does not enhance DMH-induced colon carcinogenesis in mice, even when they are fed a high-fat diet.
橄榄油对结肠癌发生的非促进作用归因于其高油酸含量，而牛油中的单不饱和脂肪与结肠肿瘤的正相关关系已有报道。在这些实验中，脂肪酸以外的成分的作用也不容忽视。为了尽量减少油中次要成分的影响，作者将传统红花油与富含油酸的红花突变株油进行了比较。
用1,2-二甲基肼（DMH，每周20mg/kg体重，共12周）处理ICR小鼠，然后给其喂食高脂肪饮食（占体重的23.5%），其中含有红花油（HF-LA）或高油酸红花油（HF-OA），或低脂肪饮食（占体重的5%），其中含有红花油（LF-LA）或高油酸红花油（LF-OA）。试验饮食持续到首次给予DMH后30周实验结束。通过气液色谱-质谱法测定结肠磷脂的脂肪酸组成。
喂食HF-OA饮食的动物的肿瘤多发性与喂食LF-LA或LF-OA的动物没有区别。相比之下，喂食HF-LA饮食的动物的结肠肿瘤（大多为腺癌）发病率明显高于其他组。结肠磷脂中的脂肪酸谱反映了饮食中的脂肪酸谱。喂食HF-LA饮食的动物结肠鞘磷脂中的神经酸（C24:1，n-9）显著减少。
这些数据表明，即使给小鼠喂食高脂肪饮食，油酸也不会增强DMH诱导的结肠癌发生。
