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

Eur J Clin Nutr. 2005 Jun;59(6):733-41. doi: 10.1038/sj.ejcn.1602121.


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+/-2.7 kg/m2) 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 160 kJ/day (95% CI: 15-305) by the simple preparation as compared to placebo, whereas the enterocoated preparation had no such effect (53 kJ/day, -92 to 198); simple vs enterocoated versions (P=0.09). The simple preparation produced a deficit in 24-h energy balance of 193 kJ/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 approximately 200 kJ 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.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Caffeine / pharmacology
  • Calcium, Dietary / pharmacology
  • Calorimetry, Indirect
  • Capsaicin / pharmacology*
  • Catechin / pharmacology
  • Central Nervous System Stimulants / pharmacology*
  • Cross-Over Studies
  • Dietary Supplements
  • Double-Blind Method
  • Energy Metabolism / drug effects*
  • Energy Metabolism / physiology
  • Heart Rate / drug effects
  • Humans
  • Male
  • Obesity / drug therapy*
  • Oxidation-Reduction
  • Plant Extracts
  • Respiration / drug effects
  • Tea*
  • Thermogenesis / drug effects
  • Tyrosine / pharmacology


  • Calcium, Dietary
  • Central Nervous System Stimulants
  • Plant Extracts
  • Tea
  • Caffeine
  • Tyrosine
  • Catechin
  • Capsaicin