Kelley D S, Erickson K L
Western Human Nutrition Research Center, ARS, USDA, Department of Nutrition, University of California Davis, Davis, California 95616, USA.
Lipids. 2003 Apr;38(4):377-86. doi: 10.1007/s11745-003-1072-2.
We have reviewed the published literature regarding the effects of CLA on body composition and immune cell functions in humans and in animal models. Results from studies in mice, hamsters, rats, and pigs generally support the notion that CLA reduced depot fat in the normal or lean strains. However, in obese rats, it increased body fat or decreased it less than in the corresponding lean controls. These studies also indicate that t10,c12-CLA was the isomer that reduced adipose fat; however, it also increased the fat content of several other tissues and increased circulating insulin and the saturated FA content of adipose tissue and muscle. Four of the eight published human studies found small but significant reductions in body fat with CLA supplementation; however, the reductions were smaller than the prediction errors for the methods used. The other four human studies found no change in body fat with CLA supplementation. These studies also report that CLA supplementation increased the risk factors for diabetes and cardiovascular disease including increased blood glucose, insulin, insulin resistance, VLDL, C-reactive protein, lipid peroxidation, and decreased HDL. Most studies regarding the effects of CLA on immune cell functions have been conducted with a mixture of isomers, and the results have been variable. One study conducted in mice with the purified c9,t11-CLA and t10,c12-CLA isomers indicated that the two isomers have similar effects on immune cell functions. Some of the reasons for the discrepancies between the effects of CLA in published reports are discussed. Although significant benefit to humans from CLA supplementation is questionable, it may create several health risks in both humans and animals. On the basis of the published data, CLA supplementation of adult human diets to improve body composition or enhance immune functions cannot be recommended at this time.
我们回顾了已发表的关于共轭亚油酸（CLA）对人体和动物模型身体组成及免疫细胞功能影响的文献。在小鼠、仓鼠、大鼠和猪身上进行的研究结果总体上支持CLA能减少正常或瘦型品系动物储存脂肪的观点。然而，在肥胖大鼠中，它会增加体脂，或者相比相应的瘦型对照减少幅度较小。这些研究还表明，反式10,顺式12 - CLA是减少脂肪组织脂肪的异构体；然而，它也会增加其他几种组织的脂肪含量，并增加循环胰岛素以及脂肪组织和肌肉中饱和脂肪酸的含量。八项已发表的人体研究中有四项发现，补充CLA后体脂有小幅但显著的减少；然而，减少幅度小于所用方法的预测误差。另外四项人体研究发现补充CLA后体脂没有变化。这些研究还报告称，补充CLA会增加糖尿病和心血管疾病的风险因素，包括血糖、胰岛素、胰岛素抵抗、极低密度脂蛋白（VLDL）、C反应蛋白、脂质过氧化增加，以及高密度脂蛋白（HDL）降低。大多数关于CLA对免疫细胞功能影响的研究是使用异构体混合物进行的，结果各不相同。一项在小鼠身上使用纯化的顺式9,反式11 - CLA和反式10,顺式12 - CLA异构体进行的研究表明，这两种异构体对免疫细胞功能有相似的影响。文中讨论了已发表报告中CLA效应存在差异的一些原因。虽然补充CLA对人类是否有显著益处值得怀疑，但它可能会给人类和动物带来一些健康风险。基于已发表的数据，目前不建议在成人饮食中补充CLA以改善身体组成或增强免疫功能。
