The food industry is increasingly active in the research and development of new ingredients and food formulations that could help combat the growing health problem. According to the International Obesity Task Force (IOTF), the overall number of overweight people worldwide could top two billion, a forecast that does not take into account the lower overweight threshold set for Asians. The new meta-analysis, led by Leah Whigham from the University of Wisconsin School of Medicine and Public Health, identified studies in which CLA's potential was tested in randomised, double-blinded, placebo-controlled trials tied to assessments of subjects' body composition. Whigham and co-workers identifed 18 studies that met their criteria. They subsequently eliminated three studies since these only used single isomers. They then focused only on studies using mixtures of trans-10, cis-12 isomers.
"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," explained Whigham. When these results were compared to those from the placebo tests, the reviewers report that CLA improved fat loss at a rate of 0.024 kg per gram of CLA per week. "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 kg/wk) and for the CLA group compared with placebo (0.09 kg/wk)," the researchers said in the study. "Given at a dose of 3.2 g/d, CLA produces a modest loss in body fat in humans," they concluded.
Earlier this week, NutraIngredients.com reported on the results of another randomised, double-blind, placebo-controlled trial, published in the Journal of Nutrition, that found that a high dose supplementation of CLA of 6.4 grams per day resulted in an increase in lean body mass of 0.64 kg. With 50 per cent of Europeans and 62 per cent of Americans classed as overweight, the food industry is waking up to the potential of products for weight loss and management, with the category already estimated to already be worth $7bn worldwide. Source: American Journal of Clinical Nutrition May 2007, Vol. 85, No. 5, 1203-1211 "Efficacy of conjugated linoleic acid for reducing fat mass: a meta-analysis in humans"
Authors: L.D. Whigham, A.C. Watras and D.A. Schoeller