Naohiko Inoue

Non-pungent capsaicin analogs (capsinoids) increase metabolic rate and enhance thermogenesis via gastrointestinal TRPV1 in mice

Capsinoids are non-pungent capsaicin analogs which increase energy expenditure like capsaicin. However, the mechanisms underlying the enhancement of their energy expenditure despite their non-pungency are poorly understood. We suggest here that capsinoids increase energy expenditure in wild-type mice, but not in transient receptor potential vanilloid 1 (TRPV1) knockout mice, implying that capsinoids increase energy expenditure via TRPV1. The jejunal administration of capsinoids to anesthetized mice raised the temperature of the colon and intrascapular brown adipose tissue. Denervation of the extrinsic nerves connected to the jejunum inhibited this temperature elevation. These findings suggest that capsinoids increase energy expenditure by activating the intestinal extrinsic nerves. Although the jejunal administration of capsinoids did not raise the tail skin temperature, an intravenous injection of capsinoids did, indicating that capsinoids could barely pass through the intestinal wall into the blood. Taken together, gastrointestinal TRPV1 may be a critical target for capsinoids to enhance energy expenditure.

Enhanced Energy Expenditure and Fat Oxidation in Humans with High BMI Scores by the Ingestion of Novel and Non-Pungent Capsaicin Analogues (Capsinoids)

The biochemical and physiological indices were monitored in 44 subjects after 4-week capsinoids (capsaicin analogues with low pungency) intake. The subjects were randomly assigned to 3 groups: CSNs3 (3 mg/kg of capsinoids), CSNs10 (10 mg/kg of capsinoids) and the control (placebo). Measurements were performed in the morning on overnight-fasted subjects. The oxygen consumption (VO2), resting energy expenditure (REE) and fat oxidation increased slightly compared to pre-administration values without any adverse effects, although the increase was not significant. The increase in fat oxidation was positively and significantly correlated with the body mass index (BMI). A meta-analysis was therefore conducted on a subgroup consisting of subjects with BMI ≥ 25 (n=28). As a result, not only VO2 increased significantly (p<0.05) in the CSNs10 group, but also REE in the CSNs10 group and fat oxidation in the CSNs3 and CSNs10 groups tended to increase (p<0.1). Consequently, a capsinoids intake would be able to enhance the energy expenditure and fat burning in humans, particularly those with high BMI.

Effects of CH-19 Sweet, a Non-Pungent Cultivar of Red Pepper, in Decreasing the Body Weight and Suppressing Body Fat Accumulation by Sympathetic Nerve Activation in Humans

‘CH-19 Sweet’ is a non-pungent red pepper and enhances the energy expenditure in humans in like manner to the pungent red pepper. We investigated in this study the effects of a repeated intake of CH-19 Sweet for two weeks on the body weight and body fat in humans. Changes in the autonomic nervous activity after ingesting CH-19 Sweet were also measured by a power spectral analysis. We established a new protocol which allows the precise detection of weight change in humans by using fewer subjects. These methods were used to show that the repeated intake of CH-19 Sweet reduced the body weight and suppressed body fat accumulation. Furthermore, the body weight loss due to the repeated intake of CH-19 Sweet was significantly correlated with the sympathetic nervous response after its ingestion. We propose that the repeated intake of CH-19 Sweet reduced the body weight and suppressed body fat accumulation by sympathetic nervous activation in humans.

Effects of CH-19 Sweet, a Non-Pungent Cultivar of Red Pepper, on Sympathetic Nervous Activity, Body Temperature, Heart Rate, and Blood Pressure in Humans

We investigated the changes in autonomic nervous activity, body temperature, blood pressure (BP), and heart rate (HR) after intake of the non-pungent pepper CH-19 Sweet and of hot red pepper in humans to elucidate the mechanisms of diet-induced thermogenesis (DIT) due to CH-19 Sweet. We found that CH-19 Sweet activates the sympathetic nervous system (SNS) and enhances thermogenesis as effectively as hot red pepper, ant that the heat loss effect due to CH-19 Sweet is weaker than that due to hot red pepper. Furthermore, we found that intake of CH-19 Sweet does not affect systolic BP or HR, while hot red pepper transiently elevates them. These results indicate that DIT due to CH-19 Sweet can be induced via the activation of SNS as well as hot red pepper, but that the changes in BP, HR, and heat loss effect are different between these peppers.

Autonomic Nervous Responses According to Preference for the Odor of Jasmine Tea

The effect of jasmine tea odor on the autonomic nervous system was investigated by a power spectral analysis of the heart rate variability. We assigned eight volunteers to two groups with either a predilection for or antipathy toward the jasmine tea odor. We tested both high- and low-intensity jasmine tea odors. The low-intensity odor was produced by diluting 20-fold the jasmine tea used for the high-intensity odor test. The low-intensity odor produced an increase in parasympathetic nervous activity in both the predilection and antipathy groups. The high-intensity odor produced an increase in parasympathetic nervous activity in the predilection group, but an increase in sympathetic nervous activity in the antipathy group. The odor of Chinese green tea, a basic ingredient of jasmine tea, produced no effects similar to those of the jasmine tea odor. These results suggest that the jasmine tea odor activated the parasympathetic nerve, whereas the higher-intensity odor activated the sympathetic nerve in those subjects who disliked the odor.