PhD student: | Anita Belza, email: anbe(at)kvl.dk |
Supervisor: | Jens Kondrup, email: jeko(at)kvl.dk |
Period: | May 2004 – November 2006 |
Financed by: | Grants from Science, Toxicology & Technology, San Francisco and from Metabolife Inc, San Diego, CA, USA. |
Background:
The prevalence of obesity is escalating among children, adolescents and adults to such a degree that WHO characterizes the condition as a worldwide epidemic. Due to the escalating prevalence of obesity it is pertinent to examine the effect of well-known harmless food ingredients on the sympathetic nervous system (SNS) activity in order to suppress appetite and increase energy expenditure (EE) in humans. It has previously been found that food ingredients such as green tea extract (GTE), caffeine and capsaicin (CAP) can decrease appetite and increase thermogenesis. How-ever, the effects are often weak when the compounds are administered separately, but are potentiated in a synergistic fashion when given as a combination. The principle mode of action is an enhance-ment of SNS activity by increasing the level of noradrenalin (NA), which causes suppression of hun-ger, enhanced satiety and stimulation of EE, covered in part by increased fat oxidation.
Overall aim of PhD study:
To investigate the ability to stimulate SNS of different food ingredients, which seem to stimulate the synthesis, increase release, prolong effect and inhibit removal of the neurotransmitter NA. The PhD study is a combination of 4 sub-studies with the aims:
1: To investigate whether the thermogenic effect of a combination of capsaicin, GTE, caffeine, tyro-sine, and calcium can increase EE acutely, whether the effect is maintained after 8-weeks of sub-chronic supplementation, and whether local effect of capsaicin in the gastric mucosa is involved in the efficacy.
2: To investigate if the thermogenic effect of the mixture of capsaicin, GTE, caffeine, tyrosine, and calcium can influence body weight reduction/maintenance and changes in body composition after 8-weeks of sub-chronic supplementation, and whether the 8-weeks supplementation can increase 24-hour fecal excretion of energy and fat, and urinary excretion of catecholamines.
3: To investigate the physiological mechanisms through which capsaicin and the mixture of capsai-cin, GTE, caffeine, tyrosine and calcium influence energy expenditure and appetite regulation by measuring the acute change in concentration of appetite regulating GI hormones, catecholamines and vagus stimulation.
