Dr Jennifer Temple and her team at the State University of New York in Buffalo set out to test claims by drinks manufacturers that the primary function of caffeine in sweet, carbonated beverages is to enhance flavour or whether it might play another role.
The researchers found that the amount of caffeine added to an unfamiliar beverage was correlated with how much teenagers liked that beverage.
Although the children increasingly preferred the caffeinated drinks over time, they showed none of the signs of tolerance or withdrawal that would suggest a developing caffeine addiction.
“Because there were no differences among kids who consume caffeine at different levels, and because these kids showed little or no evidence of tolerance or withdrawal, we believe that most of the effects of caffeine in this study are due to positive, stimulating effects,” Temple told FoodNavigator.com
Adolescents aged between 12 and 17 visited the laboratory multiple times. During each visit, they sampled an unfamiliar drink and rated their preference for that beverage.
The sodas contained varying amounts of caffeine, and the caffeinated and non-caffeinated versions were varied across participants. Over repeated testing days, participants increased their liking of the soda with the highest levels of caffeine, whereas there was no change in preference for sodas with low or no caffeine.
“We gave the majority of the kids in the caffeine group 2 mg/kg [of bodyweight] and a subset 1 mg/kg. The 2 mg/kg dose was the one that was effective,” she says.
“The average amount of caffeine given to the kids was around 100 mg, which is higher than what is found in commercial soda - about twice as high. In addition, when we gave kids the lower dose, which is more comparable to what is found in commercial soda, it did not produce the same conditioning effect as the 2 mg/kg dose.”
“Children who were not typical consumers of caffeine were just as likely to show the effect as those who were high consumers of caffeine in our sample,” says Temple.
The Finnish Food Safety Authority Evira has previously assessed the exposure of adolescents to caffeine in Nordic countries and cautions that: “A daily dose of approximately 15 mg of caffeine does not usually have adverse effects on an adolescent weighing 50 kg, but the caffeine tolerance can increase with doses exceeding 50 mg. The increased tolerance is a sign of caffeine addiction, which develops with regular use.”
Authors: J. Temple, A.M. Ziegler, A. Bendlin, Y. Kosar, A.M. Graczyk, S. O'Leary, K.E. Vattana (Department of Exercise and Nutrition Sciences; School of Public Health and Health Professions; SUNY at Buffalo, Buffalo, NY, USA).