Capseicin (Capsaicinoid)

Capsaicin (8-methyl-N-vanillyl-6-nonenamide) is the principal capsaicinoid found in Capsicum species (chili peppers). It is not a significant source of macronutrients, vitamins, or minerals itself, as it is typically consumed or applied in microgram-to-milligram quantities. Key details: • Chemical formula: C18H27NO3; molecular weight: 305.41 g/mol. • Concentration in source foods: Fresh hot peppers contain approximately 0.1–1.0% capsaicinoids by dry weight; habanero peppers can reach up to 2–3% capsaicinoids. Capsaicin typically represents 60–70% of total capsaicinoids, with dihydrocapsaicin comprising ~20–25%, and minor capsaicinoids (nordihydrocapsaicin, homodihydrocapsaicin, homocapsaicin) making up the remainder. • Scoville Heat Units (SHU): Pure capsaicin rates ~16,000,000 SHU; dietary intake from hot peppers typically delivers 0.5–5 mg capsaicin per gram of dried chili. • Bioactive co-compounds in whole pepper matrix: Vitamin C (approximately 140–240 mg per 100 g fresh pepper), provitamin A carotenoids (β-carotene, β-cryptoxanthin; up to 10,000–20,000 µg per 100 g in red varieties), vitamin E (tocopherols; ~0.7–2.0 mg per 100 g), vitamin K (~14 µg per 100 g), potassium (~320 mg per 100 g), dietary fiber (~1.5–2.0 g per 100 g fresh), and flavonoids (luteolin, quercetin). • Bioavailability: Oral capsaicin is rapidly absorbed in the stomach and upper intestinal tract with approximately 50–90% bioavailability depending on formulation and food matrix. Peak plasma concentration occurs within 45–60 minutes of oral ingestion. It is extensively metabolized hepatically via CYP450 enzymes (primarily CYP3A4 and CYP1A2) and vanilloid pathways. Half-life in plasma is approximately 24–26 minutes. Lipophilic nature (logP ~3.04) facilitates transdermal absorption, which is exploited in topical patches (e.g., 8% capsaicin patch delivers ~179 mg per 280 cm² patch). Topical bioavailability is low systemically (<1% reaches circulation) but achieves high local tissue concentrations. • Mechanism of action target: Transient receptor potential vanilloid 1 (TRPV1) channel agonist; prolonged exposure causes defunctionalization of nociceptive nerve fibers via reversible depletion of substance P and calcitonin gene-related peptide (CGRP). • Typical dietary intake: Estimated average daily capsaicin consumption ranges from 0.5–1.0 mg/day in Western diets to 25–200 mg/day in high-consumption regions (Mexico, India, Thailand, Korea). • Therapeutic doses studied: Topical creams 0.025–0.1% applied 3–4 times daily; high-concentration patches 8% (179 mg capsaicin) single application for 30–60 minutes; oral supplements 2–6 mg/day in capsule form.