Twenty-five of those dealing with health were published, along with some others, in booklet from. Their results were reaffirmed and augmented in reports at a meeting of Chinese medical and tea scientists in Beijing in November 1989. Smaller conferences have met in France and elsewhere. The sampling of the findings below indicates some of the points that have been made about the relation between tea and health. The research so far has been scattered and unsystematic in that each group seems to investigate what interests it without and comprehensive plan.
Reports are fragmentary, results are sometimes contradictory, and methodology varies.
It is often impossible to compare studies on the efficacy of the various kinds of teas because different criteria were used in evaluating them. The victory over fatigue that tea provides is a big reason for its popularity. Caffeine is what does it, and caffeine has been a matter of controversy. A stimulant, caffeine has been shown to speed reaction time, increase alertness, and improve concentration. The original intake of caffeine causes the body to create stimulant chemicals, catecholamines, that relay nerve impulses to the brain.