title: Effects of encapsulated green tea and Guarana extracts containing a mixture of epigallocatechin-3-gallate and caffeine on 24 h energy expenditure and fat oxidation in men.
abstract: It has been reported that green tea has a thermogenic effect, due to its caffeine content and probably also to the catechin, epigallocatechin-3-gallate (EGCG). The main aim of the present study was to compare the effect of a mixture of green tea and Guarana extracts containing a fixed dose of caffeine and variable doses of EGCG on 24 h energy expenditure and fat oxidation. Fourteen subjects took part to this randomized, placebo-controlled, double-blind, cross-over study. Each subject was tested five times in a metabolic chamber to measure 24 h energy expenditure, substrate oxidation and blood pressure. During each stay, the subjects ingested a capsule of placebo or capsules containing 200 mg caffeine and a variable dose of EGCG (90, 200, 300 or 400 mg) three times daily, 30 min before standardized meals. Twenty-four hour energy expenditure increased significantly by about 750 kJ with all EGCG-caffeine mixtures compared with placebo. No effect of the EGCG-caffeine mixture was observed for lipid oxidation. Systolic and diastolic blood pressure increased by about 7 and 5 mmHg, respectively, with the EGCG-caffeine mixtures compared with placebo. This increase was significant only for 24 h diastolic blood pressure. The main finding of the study was the increase in 24 h energy expenditure with the EGCG-caffeine mixtures. However, this increase was similar with all doses of EGCG in the mixtures.
authors.affiliation: Division of Kinesiology, Laval University, Ste-Foy, Québec, Canada, G1K 7P4.
authors.forename: Sonia
authors.initials: S
authors.lastname: Bérubé-Parent
authors.forename: Catherine
authors.initials: C
authors.lastname: Pelletier
authors.forename: Jean
authors.initials: J
authors.lastname: Doré
authors.forename: Angelo
authors.initials: A
authors.lastname: Tremblay
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D019540:Area Under Curve; D001628:Beverages; D002110:Caffeine / Q000008:administration & dosage*; D002153:Calorimetry, Indirect; D002392:Catechin / Q000008:administration & dosage / Q000031:analogs & derivatives*; D000697:Central Nervous System Stimulants / Q000008:administration & dosage*; D018592:Cross-Over Studies; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D004734:Energy Metabolism / Q000187:drug effects*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010084:Oxidation-Reduction; D032126:Paullinia; D010936:Plant Extracts; D013662:Tea; D022722:Thermogenesis
chemical_list: D000697:Central Nervous System Stimulants; D010936:Plant Extracts; D013662:Tea; D002110:Caffeine; D002392:Catechin; C045651:epigallocatechin gallate