Abstract
Methylxanthines present psychostimulant effects. These compounds have low toxicity and their consumption at moderate levels presents some beneficial health effects, whereas some significant risk appears at high levels. Samples of common types of methylxanthine-containing beverages and foods consumed in Spain were analyzed to determine their content. Caffeine was the methylxanthine that was most found in the samples investigated. Instant coffees gave the highest caffeine percentage (18-44 mg·g(-1)). Green and scented teas were found to have a caffeine dry-weight content (8-26 mg·g(-1)) equivalent to ground coffees (13-23 mg·g(-1)), but black and pu-erh teas (18-30 mg·g(-1)) had a higher caffeine content. The evaluation of the most conventional methods for preparing espresso coffees showed that an espresso contains between 88-116 mg of caffeine. In the case of tea beverages, the amount of caffeine present was 2-3 times smaller than in espresso coffees. Energy drinks showed a similar caffeine content (80-106 mg) as espresso coffees. Chocolates had the lowest caffeine content. It has been found that none of the foods evaluated reach the recommended daily intake limit of 400 mg of caffeine with a single dose. This limit can be reached with 4-5 doses in the case of coffees and energy drinks. In the case of chocolates, the methylxanthine compound detected at large levels was theobromine, with amounts ranging from 4 to 10 mg·g(-1) for dark chocolates.