For definition of Groups, see Preamble Evaluation . Caffeine is a methylxanthine, which occurs naturally in more than 60 plant species throughout the world. It is prepared on an industrial scale by methylation of theobromine. Caffeine is consumed in beverages such as coffee, tea and mate and in soft drinks to which caffeine is added.
Coffee is the main source of dietary caffeine consumption.
The caffeine content of beverages varies widely. Caffeine is also used in numerous prescription and non-prescription pharmaceutical preparations. 5.2 Experimental carcinogenicity data Caffeine was tested for carcinogenicity in five studies in rats by oral administration. In two of these studies, no significant difference in the incidence of tumours at any site was found. The other three studies were found to be inadequate for evaluation.