title: Nonpungent capsaicin analogs (capsinoids) increase energy expenditure through the activation of brown adipose tissue in humans.
abstract: BACKGROUND
  Capsinoids-nonpungent capsaicin analogs-are known to activate brown adipose tissue (BAT) thermogenesis and whole-body energy expenditure (EE) in small rodents. BAT activity can be assessed by [¹⁸F]fluorodeoxyglucose-positron emission tomography (FDG-PET) in humans.
  
  
  OBJECTIVE
  The aims of the current study were to examine the acute effects of capsinoid ingestion on EE and to analyze its relation to BAT activity in humans.
  
  
  METHODS
  Eighteen healthy men aged 20-32 y underwent FDG-PET after 2 h of cold exposure (19°C) while wearing light clothing. Whole-body EE and skin temperature, after oral ingestion of capsinoids (9 mg), were measured for 2 h under warm conditions (27°C) in a single-blind, randomized, placebo-controlled, crossover design.
  
  
  RESULTS
  When exposed to cold, 10 subjects showed marked FDG uptake into adipose tissue of the supraclavicular and paraspinal regions (BAT-positive group), whereas the remaining 8 subjects (BAT-negative group) showed no detectable uptake. Under warm conditions (27°C), the mean (±SEM) resting EE was 6114 ± 226 kJ/d in the BAT-positive group and 6307 ± 156 kJ/d in the BAT-negative group (NS). EE increased by 15.2 ± 2.6 kJ/h in 1 h in the BAT-positive group and by 1.7 ± 3.8 kJ/h in the BAT-negative group after oral ingestion of capsinoids (P < 0.01). Placebo ingestion produced no significant change in either group. Neither capsinoids nor placebo changed the skin temperature in various regions, including regions close to BAT deposits.
  
  
  CONCLUSIONS
  Capsinoid ingestion increases EE through the activation of BAT in humans. This trial was registered at http://www.umin.ac.jp/ctr/ as UMIN 000006073.
authors.affiliation: Laboratory of Histology and Cytology, Department of Anatomy, Hokkaido University Graduate School of Medicine, Sapporo, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Yoneshiro
authors.forename: Sayuri
authors.initials: S
authors.lastname: Aita
authors.forename: Yuko
authors.initials: Y
authors.lastname: Kawai
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Iwanaga
authors.forename: Masayuki
authors.initials: M
authors.lastname: Saito
mesh_terms: D002001:Adipose Tissue, Brown / Q000378:metabolism*; D000328:Adult; D019440:Anti-Obesity Agents / Q000008:administration & dosage*; D001481:Basal Metabolism; D002211:Capsaicin / Q000008:administration & dosage / Q000031:analogs & derivatives*; D003080:Cold Temperature; D003287:Contrast Media / Q000493:pharmacokinetics; D018592:Cross-Over Studies; D019587:Dietary Supplements; D004734:Energy Metabolism; D019788:Fluorodeoxyglucose F18 / Q000493:pharmacokinetics; D006801:Humans; D007700:Kinetics; D008297:Male; D049990:Membrane Transport Modulators / Q000008:administration & dosage; D064847:Multimodal Imaging; D049268:Positron-Emission Tomography; D016037:Single-Blind Method; D012881:Skin Temperature; D050916:TRPV Cation Channels / Q000819:agonists; D022722:Thermogenesis; D014018:Tissue Distribution; D014057:Tomography, X-Ray Computed; D055815:Young Adult
chemical_list: D019440:Anti-Obesity Agents; D003287:Contrast Media; D049990:Membrane Transport Modulators; D050916:TRPV Cation Channels; C494482:TRPV1 protein, human; D019788:Fluorodeoxyglucose F18; D002211:Capsaicin