Caffeine Variability in Unlabelled Ready-to-Drink Beverages: Laboratory Quantification and Compliance with Indonesian National Standard and U.S. Food and Drug Administration Standards

Abstract

This study quantified the caffeine content of unlabelled Ready-To-Drink (RTD) caffeinated beverages commonly consumed by Malaysian university athletes, focusing on products from tea- and coffee-shops, and to evaluate their compliance with international (U.S. Food and Drug Administration (U.S. FDA) and Indonesian National Standard (INS) safe guidelines. A total of 31 RTD beverages (20 tea shops, 11 coffee shops) were selected using purposive sampling and analysed in triplicate by validated High-Performance Liquid Chromatography (HPLC). Results were analysed using descriptive statistical analysis and inferential testing to compare mean caffeine levels between beverages. Caffeine concentrations varied markedly, ranging from 2.94–69.47 mg/100 mL in tea beverages and 9.86–432.21 mg/100 mL in coffee beverages. Most tea beverages (12 of 20) and nearly all coffee beverages (10 of 11) exceeded the INS per-serving threshold (≤50 mg), and several coffee products also surpassed the FDA limit (≤200 mg). Statistical analysis confirmed significantly higher caffeine levels in coffee-shop compared with tea-shop beverages (p<0.001). When expressed relative to body mass, multiple beverages delivered caffeine doses within or above the commonly recommended ergogenic range of 3–6 mg/kg, indicating potential for unintentional high exposure. The absence of mandatory caffeine labelling limits consumers’ ability to estimate intake and may increase the risk of excessive consumption. These findings highlight the need for regulatory action mandating accurate caffeine disclosure and reinforce the importance of caffeine literacy among athletes, practitioners and the general-public to support informed and safe caffeine use.