Epigallocatechin-3-gallate and postprandial fat oxidation in overweight / obese male volunteers - a pilot study
Résumé
Objective: Drinking green tea is associated with many health benefits, including increased fat oxidation. We tested the hypothesis that Epigallocatechin-3-gallate (EGCG), the main green tea catechin, increases fat oxidation in obese men. Methods: Ten healthy overweight/obese males (BMI 31.3 ± 0.8 kg/m2) were studied in a randomized, placebo-controlled, double-blind crossover trial. Study supplements were low EGCG (300 mg), high EGCG (600 mg), caffeine (200 mg), EGCG/caffeine (300 mg/200 mg) or placebo and were taken orally for 3 days. At the third day of supplementation, O2 consumption and CO2 production was measured by indirect calorimetry in order to assess energy expenditure and fat oxidation over 4 hours each after overnight fasting and after a standardized test meal. Results: Energy expenditure was not affected by any supplementation, neither after overnight fasting nor after the test meal. During the first 2h after overnight fasting, fat oxidation increased by 7.7 (n.s.), 15.2 (n.s.), 26.3 (p<0.05 vs. placebo), and 35.4% (p<0.01 vs. placebo and low EGCG), for low EGCG, high EGCG, caffeine, and EGCG/caffeine, respectively. During the first 2h after the meal, the mean increase in fat oxidation was 33.3 (p<0.05 vs. placebo), 20.2 (n.s.), 34.5 (p<0.05 vs. placebo), and 49.4% (p<0.05 vs. placebo) for low EGCG, high EGCG, caffeine, and EGCG/caffeine, respectively. Conclusion: Low EGCG increases postprandial fat oxidation in obese men and this to the same extent as 200 mg caffeine, while high EGCG does not exert this effect. Fasting fat oxidation is increased only by caffeine (with or without EGCG). There is no synergism of low EGCG and 200 mg caffeine. Energy expenditure is not affected by EGCG.
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