In a study published on September 30, 2006, in the journal Psychopharmacology, Steptoe and his colleagues at University College in London have shown that drinking the equivalent of four cups of strong black tea for six weeks increases the rate of relaxation after a stressful event. This randomized, double-blind, placebo-controlled study showed that levels of cortisol, a stress hormone, were lower in the tea group. In addition, platelet stickiness, an important factor that contributes to strokes and heart attacks, was also decreased significantly compared to placebo. Subjective feelings of stress were also lower in the tea group.
L-theanine, an amino acid in tea that is known for its relaxation effects in the central nervous system, and its immune enhancing effects, is likely responsible for the decrease in post-event stress. Tea polyphenols, best known for their anti-oxidant and anti-inflammatory effects, also decrease platelet stickiness in test tube experiments, and these studies show that this effect occurs in vivo in tea drinkers.
Stress reduction leads to fewer heart attacks and strokes, decreased blood pressure, lower anxiety levels, better sleep, better sex, less depression, and less obesity, to list a few benefits. This study provides yet another reason to drink large quantities of tea.