Journal Title (Medline/Pubmed accepted abbreviation): Nutr Metab
Number: August 3
Page numbers: 65
doi (if applicable): 10.1186/1743-7075-7-65
Summary of Background and Research Design
Hypothesis:Capsinoid ingestion 30 min prior to exercise would generally induce metabolic changes consistent with increased metabolic rate and lipid oxidation, namely: elevating resting oxygen consumption; a shift in metabolism (respiratory exchange ration [RER] towards greater lipid oxidation; and increase catecholamine release consistent with a stimulation of the adrenergic system). The authors further hypothesized that these changes would be maintained with moderate exercise.
Subjects: 12 healthy, nonsmoking, young males (mean age = 24 y, mean body weight = 83 kg, mean body mass index = 25.5 kg/m2). Subjects were recreationally active, exercise at least 2 times per week but no more than 5. Subjects had a VO2 max of >40 mL/kg/min.
Experimental design: Double-blind, placebo-controlled, crossover
Treatments and protocol: Subjects underwent pretrial testing to determine VO2 max on a cycle ergometer and a pretrial ride for familiarization with the workload to be studied (55% of VO2 max). On the day of each test, subjects reported to the laboratory in a fasting state and a blood sample was taken. Measurements of VO2, VCO2, ventilation (VE), and heart rate were also taken. The subjects then rested for 30 min. The sampling above was repeated and then the subjects were provided with 10 capsules that contained either a mixture of rapeseed oil and medium-chain triglyceride (control) or the same oil plus 1 mg capsinoids per capsule (total dose of 10 mg capsinoids). The capsinoids used had been extracted from the pepper fruit variety CH-19 sweet (Capsicum anuum L.). Capsinoids consisted of capsiate, dihydrocapsiate, and norhydrocapsiate in a 70:23:7 ratio as determined by HPLC. After receiving the treatment, subjects then rested for another 30 min. Following completion of this rest period, the subjects exercised on the cycle ergometer at 55% VO2 max for 90 minutes. The measurements described above were taken at the start of exercise and at 15, 30, 60, and 90 minutes during exercise. Post exercise measures were taken at 15 and 30 min after completion of exercise. Ratings of perceived exertion during exercise were also obtained.
Summary of research findings:
From 30 min before to 30 min after capsinoid ingestion, there was a significantly greater increase in resting oxygen consumption for the capsinoid treatment (~23%) compared with the control (~6%). The RER, serum free fatty acids, and plasma glycerol also declined significantly for capsinoid versus control at these time points, while norepinephrine increased. The capsinoid ingestion did not affect any variables measured during exercise, though, with the exception of blunting a slight increase in lactic acid observed at 60 minutes of exercise with the control.
Interpretation of findings/Key practice applications:
The capsinoids were of interest to the authors because, although related to capsaicin, they are non-pungent. The authors suggested that the capsinoids might deliver some of the same benefits as capsaicin, but without the increases in heart rate or blood pressure that might accompany this more pungent compound. The capsinoids did not affect exercise heart rate, but they also did not alter any of the other variables measured during exercise (except the small effect on lactate mentioned earlier). The increase in resting energy expenditure observed at rest in this study is in agreement with other studies on capsaicin and capsinoids. The effects on serum free fatty acids and glycerol suggest that capsinoids may increase fat oxidation via sympathetic nervous system activity, as evidenced by the higher level of norepinephrine at rest.