Whigham Leah D, Watras Abigail C, Schoeller Dale A
Department of Obstetrics and Gynecology, University of Wisconsin School of Medicine and Public Health, Madison, WI 53792-6188, USA.
Am J Clin Nutr. 2007 May;85(5):1203-11. doi: 10.1093/ajcn/85.5.1203.
Conjugated linoleic acid (CLA) has been shown to be an effective supplement for reducing fat mass in animals, whereas results in humans have been inconsistent.
This is a meta-analysis of human studies in which CLA was provided as a dietary supplement to test its efficacy in reducing fat mass.
We searched the PubMed database (National Library of Medicine, Bethesda, MD) and references from the resulting search to identify studies in which CLA was provided to humans in randomized, double-blinded, placebo-controlled trials and in which body composition was assessed by using a validated technique.
We identified 18 eligible studies. Of these, 3 were single-isomer studies, and results comparing CLA isomers were inconclusive. We compared the length of treatment by using studies in which a mixture of purified isomers were used and those in which purified trans-10,cis-12 isomers were used. This comparison indicated that the effect of CLA was linear for up to 6 mo and then slowly approached an asymptote at 2 y. An analysis of the dose effect indicated that fat loss compared with placebo was -0.024 kg x g CLA(-1) x wk(-1) (P=0.03). After adjustment to the median dose of 3.2 g CLA/d, CLA was effective and produced a reduction in fat mass for the CLA group alone (0.05 +/- 0.05 kg/wk; P<0.001) and for the CLA group compared with placebo (0.09 +/- 0.08 kg/wk; P<0.001)
Given at a dose of 3.2 g/d, CLA produces a modest loss in body fat in humans.
共轭亚油酸（CLA）已被证明是一种有效的补充剂，可减少动物体内脂肪量，但在人体中的效果并不一致。
本研究是对人体研究的荟萃分析，其中CLA作为膳食补充剂，以测试其在减少脂肪量方面的功效。
我们检索了PubMed数据库（美国国立医学图书馆，马里兰州贝塞斯达）以及检索结果中的参考文献，以确定在随机、双盲、安慰剂对照试验中向人体提供CLA且使用经过验证的技术评估身体成分的研究。
我们确定了18项符合条件的研究。其中，3项为单异构体研究，比较CLA异构体的结果尚无定论。我们通过使用纯化异构体混合物的研究和使用纯化反式-10，顺式-12异构体的研究来比较治疗时间。该比较表明，CLA的效果在长达6个月内呈线性，然后在2年内缓慢接近渐近线。剂量效应分析表明，与安慰剂相比，脂肪减少量为-0.024 kg×g CLA⁻¹×wk⁻¹（P = 0.03）。调整至CLA中位数剂量3.2 g/d后，CLA单独对CLA组有效且使脂肪量减少（0.05±0.05 kg/周；P<0.001）；与安慰剂相比，CLA组也有效（0.09±0.08 kg/周；P<0.001）。
以3.2 g/d的剂量给予CLA，可使人体脂肪适度减少。
