Tea is especially beneficial in returning stress hormone levels back to normal. Even after stress-inducing activities, men who drank four cups of black tea daily for six weeks in the new study experienced a quicker relief from the damaging stress hormone cortisol. Long-term exposure to cortisol has been linked with the onset of coronary heart disease.

The importance isn't so much that black tea prevents reaction to stress -- because it doesn't turn you into a zombie, after all -- but that it helps greatly in recovery from stress. At the end of the six-week study, the men in the tea-drinking group were asked to complete stressful activities such as preparing and delivering a presentation in only five minutes. These men experienced the same spike in blood pressure and cortisol as the non-tea drinkers -- however, 50 minutes after the exercise the tea drinkers stress hormone levels fell nearly 50 percent, while the non-tea drinkers had only experienced a 27 percent drop in cortisol.