Caffeine (1, 3, 7‐trimethylxanthine) in Foods: A Comprehensive Review on Consumption, Functionality, Safety, and Regulatory Matters

Abstract

Caffeine ranks as one of the top most commonly consumed dietary ingredients throughout the world. It is naturally found in coffee beans, cacao beans, kola nuts, guarana berries, and tea leaves including yerba mate. The total daily intake, as well as the major source of caffeine varies globally; however, coffee and tea are the 2 most prominent sources. Soft drinks are also a common source of caffeine as well as energy drinks, a category of functional beverages. Moderate caffeine consumption is considered safe and its use as a food ingredient has been approved, within certain limits, by numerous regulatory agencies around the world. Performance benefits attributed to caffeine include physical endurance, reduction of fatigue, and enhancing mental alertness and concentration. Caffeine has also been recently linked to weight loss and consequent reduction of the overall risks for developing the metabolic syndrome. However, the caloric contribution of caffeine-sweetened beverages needs to be considered in the overall energy balance. Despite all these benefits the potential negative effects of excessive caffeine intake should also be considered, particularly in children and pregnant women.

The effect of caffeine on energy balance

“…The intracellular signal, which produces increased lipolysis, heat production in skeletal muscle, and putative satiety signals in the liver, occurs by the inhibition of PDE and also by increasing the UCPs [2,4,59]. It has recently been demonstrated in an in vitro study that caffeine suppresses adipocytes differentiation by inhibition of C/EBPα and PPARγ expression, known as the main adipogenic transcription factors, and by promotion of the expression of negative regulators such as pre-adipocyte factor 1 and KLF2.…”

“…Glade [35] caffeine). Caffeine also antagonizes the effect of adenosine in the presynaptic nerve terminals, by reversing the adenosine-mediated inhibition of the release of CA [2,4] (see Figure 1). …”

“…Caffeine is metabolized by the liver, and through enzymatic action results in three metabolites: paraxanthine (1, 7-dimethyl-xanthine), theophylline (1, 3-dimethyl-xanthine), and theobromine (3, 7-dimethyl-xanthine) [2,3]. Paraxanthine is the major metabolite and accounts for 84% of the identified products [2]. Elevated levels of caffeine appear in the blood stream within 15-45 min of consumption, peaking around 60 min post-consumption.…”

“…Some common sources of caffeine are the kola nut, cacao bean, yerba mate, and guarana berry. However, roasted coffee beans and tea leaves (Camellia sinensis) are the world's primary sources of dietary caffeine [1,2].…”

“…Approximately 80% of the world's population consumes a caffeinated product every day, and 90% of adults in North America consume caffeine on a daily basis [2].…”