Green tea extract and catechol-O-methyltransferase genotype modify the post-prandial serum insulin response in a randomised trial of overweight and obese post-menopausal women

BackgroundGreen tea extract (GTE) may be involved in a favourable post-prandial response to high-carbohydrate meals. The catechol-O-methyltransferase (COMT) genotype may modify these effects. We examined the acute effects of GTE supplementation on the post-prandial response to a high-carbohydrate meal by assessing appetite-associated hormones and glucose homeostasis marker concentrations in women who consumed 843mg of (-)-epigallocatechin-3-gallate (EGCG) or placebo capsules for 11-12months. MethodsSixty Caucasian post-menopausal women (body mass index25.0kgm(-2)) were included in a randomised, double-blind feeding study. GTE was consumed with a breakfast meal [2784.0kJ (665.4kcal); 67.2% carbohydrate]. Blood samples were drawn pre-meal, post-meal, and every 30min for 4h. Participants completed six satiety questionnaires. ResultsPlasma leptin, ghrelin and adiponectin did not differ between GTE and placebo at any time point; COMT genotype did not modify these results. Participants randomised to GTE with the high-activity form of COMT (GTE-high COMT) had higher insulin concentrations at time 0, 0.5 and 1.0h post-meal compared to all COMT groups randomised to placebo. Insulin remained higher in the GTE-high COMT group at 1.5, 2.0 and 2.5h compared to Placebo-low COMT (P<0.02). GTE-high COMT had higher insulin concentrations at times 0, 0.5, 1.0, 1.5 and 2.0h compared to the GTE-low COMT (P0.04). Area under the curve measurements of satiety did not differ between GTE and placebo. ConclusionsGTE supplementation and COMT genotype did not alter acute post-prandial responses of leptin, ghrelin, adiponectin or satiety, although it may be involved in post-meal insulinaemic response of overweight and obese post-menopausal women.