Coffee, caffeine and health: What's in your cup?

摘要

Hundreds of millions of cups of coffee are consumed each day worldwide [1]. Its popularity can be attributed to its taste, and also to the effects of caffeine. Most consumers experience, and enjoy, increased alertness and a capacity to remain awake longer without sleep. For others, however, caffeine can have unpleasant symptoms. Caffeine has addictive properties, such that consumers habituated to caffeine-containing foods or drinks consume more of that foodstuff, and withdrawal of caffeine causes loss of alertness, and sometimes symptoms such as headache. In excess, caffeine leads to a state of excitement and anxiety [2]. Dose-responses vary. For some people even a single cup may be acutely unpleasant and cause sleeplessness with a racing mind. For others, through tolerance to increasing exposure, drinking ten times this amount may still be pleasant, partly reflecting genetic variation in susceptibility [3].