Use of Conjugated Linoleic Acid as a Nutraceutical for Weight Loss in Humans

In order to investigate the effectiveness of CLA on body weight and composition, as well as blood lipids, a double-blinded, 3-phase crossover trial will be conducted in moderately overweight (BMI=25-40 kg/m2), borderline hypercholesterolemic (LDL-C ≥ 2.5 mmol/L) men between the ages of 18-60 years. During three 8-week phases separated by 4-week washout periods, and under supervision to ensure compliance, 28 subjects will consume in random order (i) Control: 3.5 g/d of safflower oil, (ii) Clarinol G-80®: 3.5 g/d of 50:50 mixture of t10, c12 and c9, t11 CLA and (iii) c9, t11: 3.5 g/day of c9, t11 CLA. Body weight, fat mass and lean body mass will be measured at beginning and end of each phase by dual energy X-ray absorptiometry (DEXA). Baseline and endpoint blood samples will collected to determine blood lipid profile, and different safety parameters, including insulin sensitivity (HOMA-IR index), and concentrations of inflammatory (hs-CRP, TNF-α, IL-6) and oxidative (Oxidized-LDL) biomarkers. Effect of CLA consumption on fatty acid oxidation will also be measured.

Inclusion criteria

• Study subjects will be defined as overweight or obese, hyperlipidemic males, with a LDL-C level of greater than 2.5 mmol/L.Subjects will be between 18-60 years old and must have a body mass index (BMI) of 25-36 kg/m2. Subjects with thyroid diseases will be included in the study as long as they have been shown to be stable in response to their medications and thyroid therapy will have to be maintained at a stable dose throughout the study.

Exclusion criteria

• subjects taking medications and/or natural health products known to affect lipid metabolism (cholestyramine, colestipol, niacin, clofibrate, gemfibrozil, probucol, HMG CoA reductase inhibitors, high dose dietary supplements or fish oil capsules (> 4 g/day), guggul, lecithin, evening primrose oil within the last six months. In addition subjects will no be allowed to consume any of these medications during the study;
• subjects who have taken plant sterol supplements within the past six weeks and consume plant sterol supplements during the trial;
• subjects who currently have diabetes, kidney, heart or liver disease or have had any of these diseases at any time during the past 3 months. In addition any development of diabetes mellitus, kidney, heart or liver disease during the trial will lead to exclusion from the trial;
• subjects who smoke or consume large amounts of alcohol (> 2 drinks/day);
• subjects who have any major food allergies or are vegetarian;
• subjects that use natural or pharmaceutical weight loss supplements or products known to affect lipid metabolism at the beginning and end of each treatment period as well as the washout periods;
• subjects who are sensitive to the Asteraceae/Compositae family (e, g., ragweed, marigolds, daisies).