Survey of caffeine levels in retail beverages in Portugal

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Abstract
The caffeine content of 85 retail beverage samples purchased from local supermarkets between 1995 and 2004 was determined. The potential intake of caffeine through the consumption of these beverages (but excluding coffee) was estimated for students of the University of Coimbra, Portugal. The caffeine content of the beverages ranged from 47.5 to 282.5 mg l−1 for teas, from 20.1 to 47.2 mg l−1 for tea extracts samples, and from 80.7 to 168.7 mg l−1 for cola soft drinks. Caffeine was not completely absent from caffeine-free colas, and energy drinks had a far greater caffeine content than regular drinks, ranging from 21 to 2175 mg l−1. Soft drinks were consumed by 72% of the individuals, although 14% of the survey participants did not drink any of the different types of the beverages studied. Contrary to expectations for this age group, no consumptions of energy drinks was reported. Daily caffeine intake was estimated to range from 4.7 to 200 mg day−1, but with only 5% reporting a daily intake around 200 mg caffeine. Cola-type beverages were an important dietary source of caffeine for the population studied. Statistical differences in the caffeine intake between the male and female populations were found, with p = 0.014, being higher for the male population. Of the beverages studied, cola-type drinks showed statistical differences for the male population, p = 0.03, and tea showed statistical differences for female population p = 0.013, respectively.