Antioxidative Properties of Black Tea
To review the relationship between black tea consumption and adult health with emphasis on four key areas:
The Cochrane Library and MEDLINE were searched for epidemiological and clinical trials focusing on tea drunk in the 'western style'. Evidence was restricted to 1990 - 2004 and covered the following areas.
Main findingsAntioxidants - With CHD and some cancers (colorectal in particular), regular long-term consumption of black tea appears to have a protective effect. Robust evidence linking black tea to reduce CHD risk.
Hydration - Hydration appears to be satisfactory when the caffeine content is less than 250mg/cup (equivalent to five cups of tea). No evidence that all caffeine containing drinks should be avoided.
Fluoride - Fluoride in tea represents an important contribution to intakes in the UK � both through the water involved and the leaf content.
Caffeine - Effects of caffeine in tea were either positive or neutral. An increase in alertness was reported - there was no evidence for adverse effects on sleep duration or quality.
No consistent data suggests any harmful effects of black tea on dental health.
Evidence was limited in all areas except antioxidants.
Additional findings of media worth
Drinking three cups of tea for two weeks increases the concentration of flavonoids in the blood by 25%.
Long term tea drinking may increase the number of probiotic bacteria in the colon, leading to a drop in pH.
Black tea produces an increase in alertness and improvement in mood, without any adverse effects on sleep duration or quality.
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