Efficacyofconjugatedlinoleicacidforreducingfatmass-ameta-analysisinhumans临床医学论文

Efficacy of conjugated linoleic acid for reducing fat mass: a meta-analysis in humans_ÁÙ´²Ò½Ñ§ÂÛÎÄ ×

Efficacy of conjugated linoleic acid for reducing fat mass: ameta-analysis in humans_ÁÙ´²Ò½Ñ§ÂÛÎÄ ×÷ÕߣºLeah DWhigham, Abigail CWatras and Dale ASchoeller, ¡¾ÕªÒª¡¿ Background: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. Objective:This is ameta-analysis of human studies in which CLA was provided as a dietary supplement to test its efficacy in reducing fat mass. Design: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 avalidated technique. Results:We identified 18 eligible studies. Of these, 3were single-isomer studies, and results comparing CLA isomers were inconclusive. We compared the length of treatment by using studies in which amixture 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 6mo and then slowly approached an asymptote at 2y. An analysis of the dose effect indicated that fat loss compared with placebo was C0.024 kg gCLAC1 wkC1 (P =0.03). After adjustment to the median dose of 3.2 gCLA/d, CLA was effective and produced areduction 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) Conclusion:Given at adose of 3.2 g/d, CLA produces amodest loss in body fat in humans. ¡¾¹Ø¼ü´Ê¡¿ body composition obesity weight loss conjugated linoleic acid INTRODUCTION Conjugated linoleic acid (CLA) refers to agroup of positional and geometric isomers of linoleic acid that are characterized by the presence of conjugated dienes. CLA is a natural, but minor, component of fats from ruminant animals that enters the human diet primarily in meat and dairy products (1). CLA has been shown to have many biological effects, including anticarcinogenisis, antiatherogenesis, immune modulation, and changes in body composition, and is commercially available as an over-the-counter supplement (2). In nature, the most abundant isomer is cis-9,trans-11 (c9,t11), wheras in supplement forms CLA is typically sold as an equal mix of the 2 predominant isomers c9,t11 and t10,c12. Among the most controversial and highly studied physiologic effects of CLA is the influence on body composition. Many animal studies have investigated the effect of CLA on body composition, and although results vary by species, most find that CLA