The influence of caffeine on energy content of sugar-sweetened beverages: 'the caffeine-calorie effect'

Background/Objectives: Caffeine is a mildly addictive psychoactive chemical and controversial additive to sugar-sweetened beverages (SSBs). The objective of this study is to assess if removal of caffeine from SSBs allows co-removal of sucrose (energy) without affecting flavour of SSBs, and if removal of caffeine could potentially affect population weight gain. Subjects/Methods: The research comprised of three studies; study 1 used three-alternate forced choice and paired comparison tests to establish detection thresholds for caffeine in water and sucrose solution (subjects, n = 63), and to determine if caffeine suppressed sweetness. Study 2 (subjects, n = 30) examined the proportion of sucrose that could be co-removed with caffeine from SSBs without affecting the flavour of the SSBs. Study 3 applied validated coefficients to estimate the impact on the weight of the United States population if there was no caffeine in SSBs. Results: Detection threshold for caffeine in water was higher (1.09 +/- 0.08 mM) than the detection threshold for caffeine in sucrose solution (0.49 +/- 0.04 mM), and a paired comparison test revealed caffeine significantly reduced the sweetness of sucrose (P<0.001). Removing caffeine from SSBs allowed co-removal of 10.3% sucrose without affecting flavour of the SSBs, equating to 116 kJ per 500 ml serving. The effect of this on body weight in adults and children would be 0.600 and 0.142 kg, which are equivalent to 2.08 and 1.10 years of observed existing trends in weight gain, respectively. Conclusion: These data suggest the extra energy in SSBs as a result of caffeine's effect on sweetness may be associated with adult and child weight gain. European Journal of Clinical Nutrition (2011) 65, 1338-1344; doi:10.1038/ejcn.2011.123; published online 20 July 2011