title: The beta-adrenergic antagonist propranolol partly abolishes thermogenic response to bioactive food ingredients.
abstract: A combination of tyrosine, capsaicin, catechins, and caffeine has been shown to possess a thermogenic effect in humans. The present objective was to investigate whether the thermogenic response to the bioactive combination (BC) could be diminished or abolished by propranolol. Twenty-two men (age, 29.0 +/- 7.1 years; body mass index, 26.0 +/- 3.6 kg/m(2); mean +/- SD) participated in a 4-way, randomized, double-blind, placebo-controlled crossover study. The effect of the following was tested: (1) placebo, (2) BC, (3) BC + 5 mg propranolol, and (4) BC + 10 mg propranolol. Resting metabolic rate, respiratory quotient, and the thermogenic response were measured for 5 hours postintake. Systolic blood pressure (SBP), diastolic blood pressure (DBP), heart rate, and appetite ratings were assessed every half hour. The BC increased resting metabolic rate by 5% (73 [36; 110] kJ/5 h, mean [95% confidence interval], P < .0001) compared with placebo. Both propranolol doses blunted the thermogenic response by 50% compared with placebo (P < .01). The BC increased SBP by 3% (4 +/- 1 mm Hg, P = .003) compared with placebo. The effect of BC on SBP was reduced by 25% by propranolol (P = .07). The BC (with or without propranolol) increased DBP by 6% (4 +/- 1 mm Hg, P </= .0002). Propranolol decreased heart rate by 5% (3 +/- 1 beats per minute, P < .0001) compared with placebo and BC. No effects were observed on appetite ratings. In conclusion, the study confirms the thermogenic properties of BC. The 50% reduction of the thermogenic response by propranolol indicates that beta-adrenergic pathways are partly responsible for the thermogenic response.
authors.affiliation: Department of Human Nutrition, Centre for Advanced Food Studies, University of Copenhagen, DK-1958 Frederiksberg C, Denmark. anbe@life.ku.dk
authors.forename: Anita
authors.initials: A
authors.lastname: Belza
authors.forename: Maj-Britt
authors.initials: MB
authors.lastname: Gille
authors.forename: Sarah
authors.initials: S
authors.lastname: Schultz John
authors.forename: Jens
authors.initials: J
authors.lastname: Kondrup
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000494:pharmacology*; D000328:Adult; D001481:Basal Metabolism / Q000187:drug effects*; D001794:Blood Pressure / Q000187:drug effects; D002110:Caffeine / Q000494:pharmacology; D002211:Capsaicin / Q000494:pharmacology; D002392:Catechin / Q000494:pharmacology; D018592:Cross-Over Studies; D004311:Double-Blind Method; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D008297:Male; D009765:Obesity / Q000378:metabolism; D050177:Overweight / Q000378:metabolism*; D011433:Propranolol / Q000494:pharmacology*; D022722:Thermogenesis / Q000187:drug effects*; D014443:Tyrosine / Q000494:pharmacology
chemical_list: D000319:Adrenergic beta-Antagonists; D002110:Caffeine; D014443:Tyrosine; D002392:Catechin; D011433:Propranolol; D002211:Capsaicin