引言饮用含有咖啡因的饮料已遍及全球。大多数西方国家如美、英、法,习惯饮用咖啡;大多数东方国家如中、印、日,习惯用茶。还有一些国家喜欢饮含少量咖啡因的可可,“瓜拉那”等。据估计每年世界咖啡消费量已超过400万吨(Rokeitson,1978)。茶在中国的消费,也从1965年的43000吨,上升至1976年的139000吨(“中国经济年鉴”,1981)。为什么全世界范围内这样普遍地饮用咖啡和茶呢?原因是这些饮料中的咖啡因能提神解劳,提高感觉敏锐度和反应速度,使思路畅通,延长智力劳动的时间。如Nash(1962)的研究表明,咖啡因有助于成对联想学习,听觉材料的及时回忆,以及完成不完整的句子。但是近年来人们发现,咖啡因对人体有有害的作用。摄入咖啡因后,其中的甲基黄嘌呤 Introduction Drinking caffeinated beverages is worldwide. Most Western countries such as the United States, Britain, France, used to drinking coffee; most of the East countries such as China, India, Japan, used to tea. Some countries like to drink cocoa with a small amount of caffeine, “Guarana” and so on. It is estimated that the world’s coffee consumption has exceeded 4 million tons per year (Rokeitson, 1978). The consumption of tea in China rose from 43,000 tons in 1965 to 139,000 tons in 1976 (China Economic Yearbook, 1981). Why is coffee and tea commonly consumed around the world as such? The reason is that the caffeine in these drinks can help relieve fatigue, improve sensory acuity and responsiveness, smooth the mind and prolong the period of intellectual work. Studies such as Nash (1962) show that caffeine helps paired associative learning, timely recall of auditory material, and the completion of incomplete sentences. However, in recent years, people have found that caffeine has a harmful effect on the human body. After ingesting caffeine, one of the methylxanthines