Leah D Whigham1, Abigail C Watras, Dale A Schoeller. 1. Department of Obstetrics and Gynecology, University of Wisconsin School of Medicine and Public Health, Madison, WI 53792-6188, USA. lwhigham@wisc.edu
Abstract
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 a meta-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 a validated technique. RESULTS: 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) CONCLUSION: Given at a dose of 3.2 g/d, CLA produces a modest loss in body fat in humans.
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 a meta-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 a validated technique. RESULTS: 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) CONCLUSION: Given at a dose of 3.2 g/d, CLA produces a modest loss in body fat in humans.
Authors: Y Ma; K L Tucker; C E Smith; Y C Lee; T Huang; K Richardson; L D Parnell; C Q Lai; K L Young; A E Justice; Y Shao; K E North; J M Ordovás Journal: Nutr Metab Cardiovasc Dis Date: 2014-07-22 Impact factor: 4.222
Authors: Robert S Chapkin; David N McMurray; Laurie A Davidson; Bhimanagouda S Patil; Yang-Yi Fan; Joanne R Lupton Journal: Br J Nutr Date: 2008-05-20 Impact factor: 3.718