T Nation

Have Some Tea, Lower Your Cortisol


Drinking tea soothes stress, researchers say
Thursday, 5 October 2006
Cosmos Online

SYDNEY: Daily cups of tea can help you recover more quickly from the stresses of everyday life by affecting levels of the stress hormone cortisol, a new British study shows.

Published in the international journal Psychopharmacology, the study found that people who drank tea were able to de-stress more quickly than those who drank a tea substitute. Following a stressful event, tea-drinkers also had lower levels of cortisol in their blood when compared with a control group who drank placebo tea.

“Drinking tea has traditionally been associated with stress relief,” said co-author Andrew Steptoe, of the Department of Epidemiology and Public Health at University College London. Until now, however, scientific evidence for the relaxing properties of tea has been quite limited, he said.

The study involved 75 young male tea drinkers who all gave up their normal tea, coffee and caffeinated beverages for the duration of the study. Instead, they consumed a tea concoction four times a day for six weeks.

Participants were divided into two groups: one group was given a fruit-flavoured caffeinated tea mixture made up of the constituents of an average cup of black tea; the other group - the control group - was given a caffeinated placebo, identical in taste but devoid of active tea ingredients.

All drinks were tea-coloured, but were designed to mask some of the normal sensory cues associated with tea drinking (like smell, taste and familiarity of the brew) to eliminate confounding factors such as the ‘comforting’ effect of drinking a cup of tea.

Both groups were subjected to stressful tasks while their blood cortisol, blood pressure, blood platelet and self-rated levels of stress were measured.

In one task, volunteers were exposed to a stressful situation - either the threat of unemployment, a shop lifting accusation or an incident in a nursing home - and had to prepare a verbal defence and argue their case in front of a camera.

The tasks triggered substantial increases in blood pressure, heart rate and subjective stress ratings in both of the groups. However, 50 minutes after the task, cortisol levels had dropped by an average of 47 per cent in the tea drinking group compared with 27 per cent in the fake tea group.

UCL researchers also found that blood platelet activation - linked to blood clotting and the risk of heart attacks - was lower in the tea drinkers, and that this group reported a greater degree of relaxation in the recovery period after the task.

“We do not know what ingredients of tea were responsible for these effects on stress recovery and relaxation,” said Steptoe. "Nevertheless, our study suggests that drinking black tea may speed up our recovery from the daily stresses in life.

“This has important health implications, because slow recovery following acute stress has been associated with a greater risk of chronic illnesses such as coronary heart disease.”

with University College London