Haghighatdoost Fahimeh, Hariri Mitra
Food Security Research Center, Isfahan University of Medical Sciences, Isfahan, Iran.
Department of Community Nutrition, School of Nutrition and Food Science, Isfahan University of Medical Sciences, Isfahan, Iran.
Endocr Metab Immune Disord Drug Targets. 2018;18(3):185-193. doi: 10.2174/1871530318666171207143254.
There are controversies regarding the effect of conjugated linoleic acid (CLA) on serum leptin.
To conduct a meta-analysis of randomized controlled trials (RCTs) to assess the effect of CLA on serum leptin concentrations.
Databases such as Ovid, PubMed/Medline, SCOPUS, Google Scholar, and ISI databases up to January 2017 were searched. The searches included RCTs conducted among human adults, and studies on the effect of conjugated linoleic acid on serum leptin concentrations as outcome variables. The mean difference and standard deviation of leptin changes in the intervention and control groups were used as effect size measures for the meta-analysis.
Eleven trials with thirteen effect sizes were pooled in this meta-analysis. CLA supplementations could not reduce serum leptin levels significantly (-0.12 (ng/ml); 95% CI: -1.29, 1.05; P=0.837). However, the impact of CLA supplementation differed by sex and BMI status. Compared with the control group, CLA administration reduced serum leptin levels significantly in trials conducted among male (- 0.86 (ng/ml); 95% CI: -1.11, -0.62; P<0.0001) or overweight individuals (-1.37 (ng /ml); 95% CI: -2.55, -0.20; P=0.022) and lasted for less than 8 weeks (-0.90 (ng/ml); 95% CI: -1.64, -0.17; P=0.0.016).
CLA supplementation might be able to decrease circulating leptin levels in studies with duration of less than 8 weeks especially among male and overweight subjects. Additional RCTs that are well controlled for energy intakes may be necessary to explain the cause of short- and long-term effects of conjugated linoleic acid. The protocol was registered with PROSPERO (No. CRD42017059165).
共轭亚油酸（CLA）对血清瘦素的影响存在争议。
进行一项随机对照试验（RCT）的荟萃分析，以评估CLA对血清瘦素浓度的影响。
检索截至2017年1月的Ovid、PubMed/Medline、SCOPUS、谷歌学术和ISI数据库等。检索内容包括在成年人群中进行的RCT，以及以共轭亚油酸对血清瘦素浓度的影响作为结局变量的研究。干预组和对照组中瘦素变化的均值差异和标准差用作荟萃分析的效应量指标。
本荟萃分析纳入了11项试验，共13个效应量。补充CLA并不能显著降低血清瘦素水平（-0.12（ng/ml）；95%置信区间：-1.29，1.05；P = 0.837）。然而，补充CLA的影响因性别和BMI状态而异。与对照组相比，在男性（-0.86（ng/ml）；95%置信区间：-1.11，-0.62；P < 0.0001）或超重个体（-1.37（ng/ml）；95%置信区间：-2.55，-0.20；P = 0.022）中进行的试验里，补充CLA可显著降低血清瘦素水平，且持续时间少于8周的试验中也有此效果（-0.90（ng/ml）；95%置信区间：-1.64，-0.17；P = 0.016）。
在持续时间少于8周的研究中，尤其是在男性和超重受试者中，补充CLA可能能够降低循环瘦素水平。可能需要额外的对能量摄入进行良好控制的RCT来解释共轭亚油酸短期和长期影响的原因。该方案已在国际前瞻性系统评价注册库（PROSPERO）注册（编号CRD42017059165）。
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