Bioactive food stimulants of sympathetic activity: effect on 24-h energy expenditure and fat oxidation

Objective: Bioactive food ingredients influence energy balance by exerting weak thermogenic effects. We studied whether the thermogenic effect of a combination of capsaicin, green tea extract (catechins and caffeine), tyrosine, and calcium was maintained after 7-day treatment and whether local effects in the gastric mucosa were involved in the efficacy. Design: The present study was designed as a 3-way crossover, randomised, placebo-controlled, double-blinded intervention. Setting: Department of Human Nutrition, RVAU, Denmark. Subjects: A total of 19 overweight to obese men (BMI: 28.0 +/- 72.7 kg/m(2)) were recruited by advertising locally. Intervention: The subjects took the supplements for a period of 7 days. The supplements were administrated as a simple supplement with the bioactive ingredients, a similar enterocoated version, or placebo. In all, 24-h energy expenditure (EE), substrate oxidations, spontaneous physical activity (SPA), and heart rate were measured in respiration chambers on the seventh day of each test period. Results: After adjustment for changes in body weight and SPA, 24-h EE was increased by 160kJ/day (95% Cl: 15-305) by the simple preparation as compared to placebo, whereas the enterocoated preparation had no such effect (53kJ/day,-92 to 198); simple vs enterocoated versions (P=0.09). The simple preparation produced a deficit in 24-h energy balance of 193kJ/day (49-338, P=0.03). Fat and carbohydrate oxidation were equally increased by the supplements. Conclusion: A supplement containing bioactive food ingredients increased daily EE by similar to 200kJ or 2%, without raising the heart rate or any observed adverse effects. The lack of effect of the enterocoated preparation suggests that a local action of capsaicin in the gastric mucosa is a prerequisite for exerting the thermogenic effect. Sponsorship: Supported by Science, Toxicology & Technology, San Francisco, CA, USA.