Caffeine is an alkaloid chemical derived from plants, but also produced synthetically by man. Caffeine belongs to the methylxanthine group of alkaloids, which also includes theobromine found in chocolate and theophylline found in tea. The most common dietary sources of plant based caffeine are tea, coffee and chocolate. However caffeine is also added to a number of foods most notably soft drinks, and this synthetic caffeine can contribute significantly to overall intake. Studies have investigated the intakes of caffeine in Western nations and generally it appears that caffeine intake may have peaked. For example, in one study1, researchers estimated the caffeine intake of individuals living in the United States of America between 2001 and 2010. In this regard, the authors concluded that the mean intake for an adult was 186 mg per day, with men consuming 211 mg per day and women consuming somewhat less at 161 mg per day. Based on body weights, the average consumption for men and women is therefore likely similar.
However, excluding non-caffeine drinkers, the consumption per consumer increased. Amongst only consumers the authors calculated the average intake to be 211 mg per day, with men consuming 240 mg per day and women consuming 183 mg per day. The highest consumption of caffeine was estimated to be 1066 mg per day with the highest average consumption of caffeine being in the male 30 to 50 years age group. The lowest caffeine consumption was in women aged 19 to 30 years. Intakes of caffeine came primarily from coffee (64 %), tea (16 %) and soft drinks (18 %). Consumption of energy drinks still only contributed less than 1 % of caffeine, but their contribution had increased significantly since 2001. Therefore new caffeine products have been introduced to the market, and their consumption has increased, however, the authors concluded that caffeine consumption had not increased from the 2001 level by 2010. In Western populations overall caffeine intake may therefore have stabilised.
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