Black Tea and Stress Reduction
With much of the focus in the US on green and white teas due to the high content of EGCG antioxidant, I took particular interest in the study that came across my monitor regarding black tea and stress.
Drinking tea has traditionally been associated with relieving the stress brought on by our fast paced lives, butscientific research backing up those claims has been limited.
This study, conducted at University College London (UCL), is one of the first measuring teas impact on stressthrough the means of a double blind placebo controlled design, meaning neither the researchers or participants were aware of who was drinking the real tea and who was consuming the placebo or fake tea. Furthermore, both the placebo and real tea were absent of the familiar “soothing” elements such as smell and taste to avoid confusing the scientific results with traditional comforting elements, meaning any differences were due to the biological ingredients of tea and not the relaxing situations in which people might associate tea.
Researchers followed 75 young male regular tea drinkers for six weeks. Study participants were separated in to two groups and all stopped consuming their normal tea, coffee or caffeinated beverage. Group one, so labeled for the purpose of this article only, was given a caffeinated, fruit flavored tea mixture with the equivalent beneficial properties of an average cup of tea. Group two was given a similar tasting, caffeinated mixture minus teas' active, beneficial ingredients.
Both groups were subjected to tasks that triggered increases in blood pressure and heart rate and experienced similar stress level responses. So it was clear that neither group was able to avoid stress by drinking tea. But 50 minutes after exposure, the cortisol levels (a hormone released when stress is experienced) in group 1 (the tea group) had dropped by an average 47 per cent as compared with a 27 per cent decrease in group 2.
Researchers also found that blood platelet activation, linked to blood clotting and heart attacks, was lower in group one and that they reported a higher degree of relaxation in the recovery period.
Professor Andrew Steptoe, UCL Department of Epidemiology and Public Health stated that “ We do not know what ingredients of tea were responsible for these effects on stress recovery and relaxation. Tea is chemically very complex, with many different ingredients. Ingredients such as catechins, polyphenols, flavonoids and amino acids have been found to have effects on neurotransmitters in the brain, but we cannot tell from this research which ones produced the differences. Nevertheless, 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. 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.”