ITAMI, Japan—A combination of caffeine, arginine, soy isoflavones and L-carnitine may help control obesity, according to a study published in the October issue of the Journal of Nutrition (2007; 137:2252-2257). In developing an anti-obesity dietary supplement, researchers from Japan and Korea focused on lipolysis and fatty acid oxidation. They selected caffeine, a nonselective adenosine-receptor antagonist, and arginine (CA), an inducer of lipolytic hormone, for their ability to stimulate lipolysis; they also added soy isoflavones, which stimulate carnitine palmitoyl transferase 1A, and L-carnitine (SL), a cofactor for beta-oxidation of fatty acids, to enhance fatty acid oxidation.
The effects of a combination of CA and SL (CASL) on lipid metabolism were studied in vitro and in vivo. During 3T3-L1 differentiation—3t3 cells differentiate into adipocyte phenotypes—lipid accumulation was significantly lower in cells treated with CASL (50 µmol/L, 1 mmol/L, 1 µmol/L, and 1 mmol/L, respectively), compared with each ingredient alone. Lipolysis was also significantly greater in 3T3-L1 adipocytes treated with CASL (50 µmol/L, 1 mmol/L, 10 µmol/L and 0.5 mmol/L, respectively), compared with each alone. In addition, treatment with higher concentrations of CASL (2 mmol/L, 1 mmol/L, 10 µmol/L, and 1 mmol/L, respectively) significantly enhanced beta-oxidation in HepG2 cells, a liver line used to study cholesterol and triglyceride metabolism.
The effects of CASL-containing diets (250 mg, 6 g, 200 mg, and 1.5 g/kg diet, respectively) were studied in vivo. When KK mice (non-insulin-dependent diabetes mellitus with moderate obesity) were deprived food for 48 hours and subsequently re-fed a fat-free diet for 72 hours, hepatic triglyceride (TG) accumulation was significantly lower in mice fed CASL compared with the control mice. In addition, after obese KK mice were fed a low-fat diet for two weeks, adipose tissue weights were significantly lower in those fed CASL, but not CA or SL alone. Plasma and liver TG levels were also lower in mice fed CASL than in the control mice. Researchers concluded the results suggest a combination of caffeine, arginine, soy isoflavones and L-carnitine is effective for controlling obesity.
