Caffeine levels and voluntary labelling accuracy of guarana-containing solid foods in Korea: A pre-implementation...

Caffeine labelling requirements in the Republic of Korea were revised in 2024, with expanded provisions for guarana-containing solid foods implemented on 1 January 2026. This study quantified caffeine concentrations in 61 guarana-containing solid and semi-solid products purchased in Korea (2020-2021), prior to the enforcement of the revised requirements, using HPLC with diode-array detection (HPLC-DAD). Single-serving caffeine intake was estimated based on labelled serving sizes and compared against established safety benchmarks. For powdered products, caffeine concentrations ranged from 0.2 to 30.2 mg/g, yielding up to 218.7 mg per maximum labelled serving. Single-serving exposure peaked at 4.4 mg/kg body weight (bw) for a 50 kg adolescent, exceeding the conservative daily intake screening value of 2.5 mg/kg bw/day, applied under a one-serving-per-day worst-case assumption. This exposure also accounted for approximately 109% of the 200-mg single-dose reference and 55% of the 400-mg/day guidance level for adults. Eight powdered products exceeded a hazard quotient (HQ) of 1 for adolescents under a conservative one-serving-per-day screening scenario. The HQ framework was used solely as a screening tool to identify products requiring further scrutiny; HQ values > 1 should not be interpreted as evidence of adverse health effects. Applying Korea's current high-caffeine criterion for guarana-containing solid foods (≥ 0.15 mg/g), 59 of 61 products (96.7%) would require mandatory quantitative disclosure; however, only 14 of 61 (23.0%) provided such information at the time of purchase. These findings establish a pre-implementation baseline for post-2026 market monitoring.