Acute effects of hot red chili on autonomic and metabolic functions in healthy subjects

To investigate if chili consumption as a food ingredient in a fried rice meal would have any real acute pharmacological effects on autonomic nervous system (ANS) and metabolic system (MS), a randomized, cross-over, intervention trial was conducted in 33 healthy subjects. The study found that a moderate dose of chili (containing 16.96 - 24.40 mg capsaicin plus 4.86 - 6.99 mg dihydrocapsaicin) given in a meal significantly increased systolic blood pressure and decreased rMSSD (the square root of mean of sum of square of successive difference) parameter of heart rate variability reflecting a reduced parasympathetic function of the ANS. Chili also affected MS by significantly reducing the body temperature, but not other MS parameters. Time-passing also had highly significant effects on ANS and MS. However, the linear mixed modeling revealed that there was little evidence that chili modified the physiological response over a 180 min period. This result suggests that the body's strong physiologic responses modulate any chili effects to the extent that there are minimal differential responses over the experimental period. These findings confirmed that moderate amount of chili in food have significant acute effects on the modulation of ANS and MS but not therapeutic effect on weight reduction