Richardson Centre for Functional Foods and Nutraceuticals, 196 Innovation Drive, Smartpark, University of Manitoba, Winnipeg, Manitoba R3T 6C5, Canada.
J Am Coll Nutr. 2010 Apr;29(2):152-9. doi: 10.1080/07315724.2010.10719829.
Dietary conjugated linoleic acid (CLA) represents a group of positional and geometric isomers of conjugated dienoic derivatives of linoleic acid. The effects of dietary CLA on blood lipids and body composition in humans remain controversial.
To examine whether consumption of milk enriched naturally or synthetically with cis 9, trans 11 (c-9, t-11) and trans 10, cis 12 (t-10, c-12) CLA isomers alters blood lipid indices, including concentrations of total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and triacyglycerol; indices of liver function including plasma alanine transaminase and total bilirubin; C-reactive protein; tumor necrosis factor-alpha; and body weight and composition in moderately overweight, borderline hyperlipidemic humans.
A randomized, 3-phase, crossover, single-blind clinical trial was carried out in moderately overweight, borderline hyperlipidemic individuals who consumed (1) milk naturally enriched in CLA (4.2%) containing c-9, t-11 only providing 1.3 g/d of CLA; (2) milk enriched with a 4.2% synthetic mixture of t-10, c-12 and c-9, t-11 CLA isomers providing 1.3 g/d of CLA; or (3) untreated milk as a control providing 0.2 g/d CLA. Dietary phases were each 8 weeks in duration and were separated by 4-week washout periods. Plasma lipid levels were measured in blood samples collected at the beginning and end of each dietary phase. Magnetic resonance imaging was carried out at the beginning and end of each dietary phase to assess any changes in regional body fat composition.
Compared with the control intervention, consumption of the two CLA-enriched milks failed to alter plasma total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, or triacyglycerol concentrations; body weight; or fat composition. CLA consumption did not significantly affect plasma alanine transaminase, total bilirubin, C-reactive protein, or tumor necrosis factor-alpha concentrations.
Results from this study fail to support the role of milk enriched naturally with CLA containing c-9, t-11 or synthetically with c-9, t-11 and t-10, c-12 CLA isomers in modulation of lipid profiles or body composition in moderately overweight, borderline hyperlipidemic individuals.
饮食共轭亚油酸（CLA）代表一组共轭二烯衍生的亚麻酸的位置和几何异构体。饮食 CLA 对人体血脂和身体成分的影响仍存在争议。
研究天然或合成富含顺式 9，反式 11（c-9，t-11）和反式 10，顺式 12（t-10，c-12）CLA 异构体的牛奶消费是否会改变血脂指数，包括总胆固醇、低密度脂蛋白胆固醇、高密度脂蛋白胆固醇和三酰甘油的浓度；肝功能指数，包括血浆丙氨酸转氨酶和总胆红素；C 反应蛋白；肿瘤坏死因子-α；以及超重、边缘性高脂血症人群的体重和成分。
在超重、边缘性高脂血症个体中进行了一项随机、3 期、交叉、单盲临床试验，这些个体分别摄入（1）天然富含 CLA（4.2%）的牛奶，仅含有 c-9，t-11，提供 1.3 g/d 的 CLA；（2）富含 4.2% 合成 t-10，c-12 和 c-9，t-11 CLA 异构体混合物的牛奶，提供 1.3 g/d 的 CLA；或（3）作为对照的未处理牛奶，提供 0.2 g/d CLA。每个膳食阶段持续 8 周，每个阶段之间有 4 周的洗脱期。在每个膳食阶段开始和结束时采集血样测量血浆脂质水平。在每个膳食阶段开始和结束时进行磁共振成像，以评估局部体脂成分的任何变化。
与对照干预相比，摄入两种富含 CLA 的牛奶并不能改变血浆总胆固醇、低密度脂蛋白胆固醇、高密度脂蛋白胆固醇或三酰甘油浓度、体重或脂肪成分。CLA 消耗并未显著影响血浆丙氨酸转氨酶、总胆红素、C 反应蛋白或肿瘤坏死因子-α浓度。
本研究结果不支持富含含有 c-9，t-11 的 CLA 的天然牛奶或富含 c-9，t-11 和 t-10，c-12 的合成 CLA 的牛奶在调节超重、边缘性高脂血症个体的血脂谱或身体成分中的作用。
