The beta-adrenergic antagonist propranolol partly abolishes thermogenic response to bioactive food ingredients

Area of Science:

• Human physiology
• Pharmacology
• Nutritional science

Background:

• A combination of tyrosine, capsaicin, catechins, and caffeine (bioactive combination, BC) is known to increase thermogenesis.
• The role of beta-adrenergic pathways in mediating this thermogenic response is not fully understood.

Purpose of the Study:

• To investigate the effect of propranolol, a beta-adrenergic blocker, on the thermogenic response to the bioactive combination (BC).
• To determine the involvement of beta-adrenergic pathways in the thermogenic effects of BC.

Main Methods:

• A 4-way, randomized, double-blind, placebo-controlled crossover study involving 22 men.
• Participants received placebo, BC, BC + 5 mg propranolol, or BC + 10 mg propranolol.
• Measurements included resting metabolic rate, respiratory quotient, blood pressure, heart rate, and appetite ratings over 5 hours.

Main Results:

• The BC significantly increased resting metabolic rate by 5% compared to placebo.
• Both doses of propranolol blunted the thermogenic response to BC by 50%.
• BC increased systolic and diastolic blood pressure; propranolol reduced the systolic effect but not the diastolic effect. Propranolol decreased heart rate.

Conclusions:

• The study confirms the thermogenic properties of the bioactive combination (BC).
• Beta-adrenergic pathways are partly responsible for the thermogenic response to BC, as evidenced by the 50% reduction in effect by propranolol.
• The findings provide insight into the physiological mechanisms underlying the thermogenic effects of dietary compounds.