Tsubura A, Yuri T, Yoshizawa K, Uehara N, Takada H
Department of Pathology II, Kansai Medical University, Takii Hospital, Moriguchi, Osaka, Japan.
Histol Histopathol. 2009 Feb;24(2):223-34. doi: 10.14670/HH-24.223.
International variation in breast and colon cancer incidence is positively related to total fat intake. However, total fat consists of different fatty acid families, e.g., saturated fatty acids (SFAs), monounsaturated fatty acids (MUFAs), and n-3 and n-6 polyunsaturated fatty acids (PUFAs). Epidemiological evidence and experimental studies suggest that these fatty acid families have different effects on breast and colon carcinogenesis. Therefore the action of each fatty acid on carcinogenesis should be evaluated separately. Although it is difficult to establish firm conclusions on the effect of each fatty acid in human epidemiological studies, experimental studies on animals and cultured cells suggest that n-6 PUFAs (linoleic acid and arachidonic acid) may have a tumor promoting effect, while n-3 PUFAs (eicosapentaenoic acid, docosahexaenoic acid and alpha-linolenic acid) and conjugated fatty acids (CFAs; a mixture of positional and geometric isomers of PUFAs with conjugated double bonds) exert an inhibitory effect on tumor growth. SFAs such as palmitic acid and stearic acid show little or no tumor promoting effect, and the action of oleic acid, a MUFA, is inconclusive. In addition to regulation of abnormal cell growth seen in cancers, fatty acids also control cell loss seen in degenerative eye diseases, such as degeneration of lens material in cataract and degeneration of photoreceptor cells in retinitis pigmentosa. Experiments suggest that n-6 PUFAs cause deleterious effects, while n-3 PUFAs result in beneficial effects on the lens and retina. In particular, docosahexaenoic acid is known to be effective in rescuing photoreceptor cells from damage. Thus, understanding the function of each fatty acid is likely to be important for making progress in treating these and other diseases.
乳腺癌和结肠癌发病率的国际差异与总脂肪摄入量呈正相关。然而，总脂肪由不同的脂肪酸家族组成，例如饱和脂肪酸（SFA）、单不饱和脂肪酸（MUFA）以及n-3和n-6多不饱和脂肪酸（PUFA）。流行病学证据和实验研究表明，这些脂肪酸家族对乳腺癌和结肠癌的致癌作用具有不同影响。因此，应分别评估每种脂肪酸对致癌作用的影响。尽管在人类流行病学研究中很难就每种脂肪酸的作用得出确凿结论，但对动物和培养细胞的实验研究表明，n-6多不饱和脂肪酸（亚油酸和花生四烯酸）可能具有促肿瘤作用，而n-3多不饱和脂肪酸（二十碳五烯酸、二十二碳六烯酸和α-亚麻酸）以及共轭脂肪酸（CFA；具有共轭双键的多不饱和脂肪酸的位置和几何异构体的混合物）对肿瘤生长具有抑制作用。棕榈酸和硬脂酸等饱和脂肪酸几乎没有或没有促肿瘤作用，单不饱和脂肪酸油酸的作用尚无定论。除了调节癌症中出现的异常细胞生长外，脂肪酸还控制退行性眼病中出现的细胞损失，例如白内障中晶状体物质的退化和视网膜色素变性中光感受器细胞的退化。实验表明，n-6多不饱和脂肪酸会产生有害影响，而n-3多不饱和脂肪酸对晶状体和视网膜具有有益影响。特别是，二十二碳六烯酸已知对挽救光感受器细胞免受损伤有效。因此，了解每种脂肪酸的功能可能对治疗这些疾病和其他疾病取得进展很重要。
