Effects of Capsinoid Intake on Brown Adipose Tissue Vascular Density and Resting Energy Expenditure in Healthy, Middle-Aged Adults: A Randomized, Double-Blind, Placebo-Controlled Study

Capsinoids are some of the most promising ingredients to increase energy expenditure (EE) due to brown adipose tissue (BAT) activation. However, there is limited information regarding the effect of prolonged capsinoid ingestion (CI) on BAT activity and resting EE (REE) in healthy, middle-aged, normal to overweight subjects (Sub(healthy)) with distinct BAT characteristics. We examined the changes in BAT density (BAT-d), using near-infrared time-resolved spectroscopy, and REE/kg induced by daily CI. Forty Sub(healthy) [age, 43.8 (mean) years; BMI, 25.4 kg/m(2)] received either capsinoid (9 mg/day) or a placebo daily for 6 weeks in a double-blind design. Total hemoglobin concentration in the supraclavicular region ([total-Hb](sup)), an indicator of BAT-d, and REE/kg were measured. The changes in post-intervention [total-Hb](sup) were greater in the capsinoid group (CA-G) than in the placebo group (PL-G) [5.8 mu M (+12.4%) versus 1.0 mu M (+2.1%); p = 0.017]. There was a significant relationship between BAT-d and REE/kg; however, post-supplementation REE/kg was not significantly different between the two groups (p = 0.228). In the overweight subgroup, changes in REE/kg were greater in the CA-G than in the PL-G [0.6 cal/kg/min (+4.3%) versus -0.3 cal/kg/min (-2.1%); p = 0.021]. CI enhanced [total-Hb](sup), a reflection of BAT-d, showing a good correlation with REE in Sub(healthy).