The efficacy of long-term conjugated linoleic acid (CLA) supplementation on body composition in overweight and obese individuals: a systematic review and meta-analysis of randomized clinical trials
- 2.6k Downloads
Numerous supplements containing conjugated linoleic acid (CLA) are presently being promoted for body weight reduction. The aim of this systematic review is to evaluate the evidence for or against the long-term efficacy of CLA.
Electronic searches were conducted to identify relevant randomized clinical trials (RCTs). No restrictions in age, time, or language were imposed. Studies had to be at least 6 months in duration. Three reviewers independently determined the eligibility of studies. Two reviewers independently extracted data and assessed the reporting quality of all RCTs.
Fifteen RCTs were identified, and seven were included. Four of the included RCTs had serious flaws in the reporting of their methodology. A meta-analysis revealed a statistically significant difference in weight loss favouring CLA over placebo (mean difference: −0.70 kg; 95% confidence interval: −1.09, −0.32). Our meta-analysis also revealed a small significant difference in fat loss favouring CLA over placebo (MD: −1.33 kg; 95% CI: −1.79, −0.86; I 2 = 54%). The magnitude of these effects is small, and the clinical relevance is uncertain. Adverse events included constipation, diarrhea, and soft stools.
The evidence from RCTs does not convincingly show that CLA intake generates any clinically relevant effects on body composition on the long term.
KeywordsObesity Body weight Body fat Weight loss Fat loss Meta-analysis
Conflict of interest
IJO has a research fellowship funded by GlaxoSmithKline. The funder had no role in any aspect of this project or the preparation of this manuscript. PPP, LKW, LAD, and EE declare no competing interests.
- 4.Whigham LD, Watras AC, Schoeller DA (2007) Efficacy of conjugated linoleic acid for reducing fat mass: a meta-analysis in humans. Am J Clin Nutr 85(5):1203–1211Google Scholar
- 5.Brown J, McIntosh M (2003) Conjugated linoleic acid in humans: regulation of adiposity and insulin sensitivity. J Nutr 133:3041–3046Google Scholar
- 6.Mirand PP, Arnal-Bagnard MA, Mosoni L et al (2004) Cis-9, trans-11 and trans-10, cis-12 conjugated linoleic acid isomers do not modify body composition in adult sedentary or exercised rats. J Nutr 134(9):2263–2269Google Scholar
- 7.Baddini FA, Fernandes PA, Ferreria da Costa N, Gonçalves RB (2009) Conjugated linoleic acid (CLA): effect modulation of body composition and lipid profile. Nutr Hosp 24(4):422–428Google Scholar
- 10.Altman DG, Schulz KF, Moher D, Egger M, Davidoff F, Elbourne D, Gøtzsche PC, Lang T (2001) The revised CONSORT statement for reporting randomised trials: explanation and elaboration. Ann Intern Med 134(8):663–694Google Scholar
- 11.Review Manager (RevMan) [Computer Program] (2008) Version 5.0. The Nordic Cochrane Centre, The Cochrane Collaboration, CopenhagenGoogle Scholar
- 12.Gaullier J-M, Halse J, Høye K, Kristiansen K, Fagertun H, Vik H et al (2005) Supplementation with conjugated linoleic acid for 24 months is well tolerated by and reduces body fat mass in healthy, overweight humans. J Nutr 135:778–784Google Scholar
- 13.Venkatramanan S, Joseph SV, Chouinard PY, Jacques H, Farnworth ER, Jones PJH (2010) Milk enriched with conjugated linoleic acid fails to alter blood lipids or body composition in moderately overweight, borderline hyperlipidemic individuals. J Am Coll Nutr 29(2):152–159Google Scholar
- 14.Von Loeffelholz C, von Loeffelholz B, Jahreis G (1999) Influence of CLA supplementation on body composition and strength in body builders. Vitamins and Additives in Human and Animal Nutrition 238–243Google Scholar
- 16.Tarnopolsky M, Zimmer A, Jeremy P, Safdar A, Aboud A, Pearce E, et al (2007) Creatine monohydrate and conjugated linoleic acid improve strength and body composition following resistance exercise in older adults. PLoS ONE 2(10):E991. doi: 10.1371/journal.pone.0000991
- 17.Moya MJ (2007) Use of conjugated linoleic acid in obese children and adolescents. Revista Espanola de Pediatria 63(3):453–457Google Scholar
- 18.Close RN, Schoeller DA, Watras AC, Nora EH (2007) Conjugated linoleic acid supplementation alters the 6-mo change in fat oxidation during sleep. Am J Clin Nutr 86:797–804Google Scholar
- 21.Gaullier J-M, Halse J, Høye K, Kristiansen K, Fagertun H, Vik H et al (2004) Conjugated linoleic acid supplementation for 1 year reduces body fat mass in healthy overweight humans. Am J Clin Nutr 79(6):1118–1125Google Scholar
- 22.Larsen TM, Toubro S, Gudmundsen O, Astrup A (2006) Conjugated linoleic acid supplementation for 1 year does not prevent weight or body fat regain. Am J Clin Nutr 83(3):606–612Google Scholar
- 23.Racine NM, Watras AC, Carrel AL, Allen DB, McVean JJ, Clark RR, et al (2010) Effect of conjugated linoleic acid on body fat accretion in overweight or obese children. Am J Clin Nutr. doi: 10.3945/ajcn.2009.28404
- 30.(1998) Safflower oil consumption does not increase plasma conjugated linoleic acid concentrations in humans. Am J Clin Nutr 67(2):332–337Google Scholar
- 31.Raff M, Tholstrup T, Basu S, Nonboe P, Sørensen MT, Straarup EM (2008) A diet rich in conjugated linoleic acid and butter increases lipid peroxidation but does not affect atherosclerotic, inflammatory or diabetic risk markers in healthy young men. J Nutr 138(3):509–514Google Scholar
- 32.Avenell A, Sattar N, Lean M (2007) Management: part I-behaviour change, diet, and activity. In: Sattar N, Lean M (eds) ABC of obesity. Blackwell, Malden, pp 8–11Google Scholar