J Lipid Res. 2003 Aug 16 Efficacy and safety of dietary supplements containing conjugated linoleic
acid (CLA) for the treatment of obesity-evidence from animal and human studies.
Larsen TM, Toubro S, Astrup A.
Dietary supplements containing CLA are widely promoted as weight loss agents available over the
counter and via the Internet. In this review we evaluate the efficacy and safety of CLA
supplementation based on peer reviewed published results from randomized placebo-controlled human
intervention trials lasting more than 4 weeks. We also review findings from experimental studies in
animals and studies performed in vitro. Overall, CLA appears to produce loss of fat mass and
increase lean tissue mass in rodents, but the results from 13 randomized, controlled short term (<6
months) trials in humans revealed only little evidence to support that CLA reduces body weight or
promotes repartitioning of body fat into fat free mass in man. However, from mice and human studies
there is increasing evidence that the CLA isomer t10,c12 may produce liver hypertrophy and insulin
resistance via a redistribution of fat deposition that resembles lipodystrophy. CLA also decreases
the fat content of the milk among lactating women and cows. In conclusion, although CLA may
attenuate increases in body weight and body fat in several animal models, CLA isomers sold as
dietary supplements does not prove effective as weight loss agents in humans and may actually
adversely affect human health. PMID: 12923219