Corl Benjamin A, Barbano David M, Bauman Dale E, Ip Clement
Department of Animal Science and. Department of Food Science, Cornell University, Ithaca, NY 14853, USA.
J Nutr. 2003 Sep;133(9):2893-900. doi: 10.1093/jn/133.9.2893.
The present study was designed to examine the effects of increasing dietary levels of vaccenic acid (VA) and cis-9, trans-11 conjugated linoleic acid (CLA) on chemically induced mammary carcinogenesis in rats. Both fatty acids were provided as a natural component in butter fat. The conversion of VA to CLA by delta9-desaturase was documented previously in several species, including rats and humans. Specifically, our objective was to determine the relative contribution of dietary VA and CLA to the tissue concentration of CLA and its ability to inhibit the development of mammary carcinomas. A total of 7 diets were formulated with varying levels of CLA and VA. The overall dietary treatment scheme was designed to evaluate the modulation of mammary cancer risk by 1). small increases of CLA in the presence of a low level of VA and 2). more substantial increases of VA against a background of low levels of CLA. As expected, small increases in dietary CLA at the low end of the CLA dose-response range did not reduce tumorigenesis. In contrast, there was a distinct and marked inhibitory response to VA that was dose dependent. The effect of VA was magnified in this experiment because the dose range of VA tested was much broader than that of CLA. Fatty acid analysis showed that the conversion of dietary VA to CLA resulted in a dose-dependent increase in the accumulation of CLA in the mammary fat pad, which was accompanied by a parallel decrease in tumor formation in the mammary gland. The finding confirms that the conversion of VA to CLA is as important for cancer prevention as the dietary supply of CLA. Thus, VA is also anticarcinogenic, and VA and CLA represent functional food components that are present in ruminant fat.
本研究旨在探讨增加膳食中vaccenic酸（VA）和顺式-9，反式-11共轭亚油酸（CLA）水平对大鼠化学诱导的乳腺癌发生的影响。两种脂肪酸均作为黄油脂肪中的天然成分提供。先前已在包括大鼠和人类在内的几种物种中记录了VA通过δ9-去饱和酶转化为CLA的过程。具体而言，我们的目标是确定膳食VA和CLA对CLA组织浓度的相对贡献及其抑制乳腺癌发生的能力。共配制了7种含有不同水平CLA和VA的日粮。总体日粮处理方案旨在评估以下因素对乳腺癌风险的调节作用：1）在低水平VA存在下少量增加CLA；2）在低水平CLA背景下大幅增加VA。正如预期的那样，在CLA剂量反应范围低端少量增加膳食CLA并不能降低肿瘤发生。相反，对VA有明显且显著的抑制反应，且呈剂量依赖性。在本实验中，VA的作用被放大了，因为所测试的VA剂量范围比CLA宽得多。脂肪酸分析表明，膳食VA转化为CLA导致乳腺脂肪垫中CLA积累呈剂量依赖性增加，同时乳腺肿瘤形成相应减少。这一发现证实，VA转化为CLA对癌症预防与膳食中CLA供应同样重要。因此，VA也具有抗癌作用，VA和CLA是反刍动物脂肪中存在的功能性食品成分。
