Researchers in tea-loving London found people who drank black tea were able to de-stress more quickly than those who drank a fake tea substitute. In addition, tea drinkers had lower levels of the stress hormone cortisol after exposure to stress.
"Our study suggests that drinking black tea may speed up our recovery from the daily stresses in life. Although it does not appear to reduce the actual levels of stress we experience, tea does seem to have a greater effect in bringing stress hormone levels back to normal," says researcher Andrew Steptoe, of the University College London, in a news release. "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."
Black Tea Fights Stress
In the study, 75 young healthy male tea drinkers (average age 33) gave up their normal tea, coffee, and caffeinated beverages and were divided into two groups. For six weeks, one group drank a fruit-flavored caffeinated black tea mixture containing the active ingredients of a cup of tea, and the other drank an identical-tasting mixture containing the same amount of caffeine but without any other active tea ingredients.
Both groups were then subjected to challenging tasks designed to mimic everyday stresses, like the threat of unemployment or an accusation, while their stress hormone, blood pressure, heart rate, and self-reported levels of stress were monitored.
The tasks provoked sharp increases in blood pressure, heart rate, and subjective stress ratings in both groups. But 50 minutes after the stressful situation, levels of the stress hormone cortisol had dropped lower among black tea drinkers compared with the fake tea group. There was also an increase in subjective relaxation during the time after the stressful situation in the tea mixture drinkers compared with the fake tea group.
In addition, researchers also found that blood platelet activation was lower among black tea drinkers. Men who drank black tea also reported feeling more relaxed after the task than the other group. Platelet activation is involved in the formation of a blood clot, which increases risk of heart attack.
New Evidence for Old Remedy
"Drinking tea has traditionally been associated with stress relief, and many people believe that drinking tea helps them relax after facing the stresses of everyday life," says Steptoe. "However, scientific evidence for the relaxing properties of tea is quite limited."
In this study, the participants did not know who was drinking real or fake tea. Researchers say that means any differences were due to the active ingredients in the tea and not to the relaxing ritual of drinking it or its taste.
Steptoe says they don't know exactly which ingredients in black tea were responsible for these effects on stress recovery and relaxation. But tea is rich in many candidates, such as catechins, polyphenols, flavonoids, and amino acids, which are under investigation for a variety of healthy benefits.
Their results appear in the journal Psychopharmacology.
SOURCES: Steptoe, A. Psychopharmacology, Sept. 30, 2006 online edition. News release, University College London.
By Jennifer Warner
Reviewed by Louise Chang