Capsaicin-induced satiety is associated with gastrointestinal distress but not with the release of satiety hormones

Background: Capsaicin, which is the major pungent principle in chili peppers, is able to induce satiety and reduce caloric intake. The exact mechanism behind this satiating effect is still unknown. We hypothesized that capsaicin induces satiety through the release of gastrointestinal peptides, such as glucagon-like peptide-1 (GLP-1) and peptide YY (PYY), from enteroendocrine cells in the small intestine. Objective: We investigate the effects of an intraduodenal capsaicin infusion (1.5 mg pure capsaicin) in healthy volunteers on hunger, satiety, and gastrointestinal symptoms and the release of GLP-1 and PYY. Design: Thirteen participants (7 women) [mean +/- SEM age: 21.5 +/- 0.6 y; body mass index (in kg/m(2)): 22.8 +/- 0.6] participated in this single-blind, randomized, placebo-controlled crossover study with 2 different treatments. During test days, an intraduodenal infusion of either capsaicin or a placebo (physiologic saline) was performed with the use of a nasoduodenal catheter over a period of 30 min. Visual analog scale scores were used to measure hunger, satiety, and gastrointestinal symptoms. Blood samples were drawn at regular intervals for GLP-1 and PYY. Gallbladder volumes were measured with the use of real-time ultrasonography. Results: The intraduodenal capsaicin infusion significantly increased satiety (P-treatment effect < 0.05) but also resulted in an increase in the gastrointestinal symptoms pain (P-treatment X time interaction < 0.0005), burning sensation (P-treatment X time interaction < 0.0001), nausea (P-treatment X time interaction < 0.05), and bloating (P-treatment X time interaction < 0.001) compared with the effects of the placebo infusion. Satiety scores had a positive correlation with all gastrointestinal symptoms. No differences in GLP-1 and PYY concentrations and gallbladder volumes were observed after the capsaicin infusion compared with after the placebo infusion. Conclusions: An intraduodenal infusion of capsaicin significantly increases satiety but does not affect plasma concentrations of GLP-1 and PYY. Rather, the effect on satiety seems related to gastrointestinal stress as shown by the associations with pain, burning sensation, nausea, and bloating scores. This trial was registered at clinicaltrials.gov as NCT01667523.