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Tea, Caffeine and your body
Caffeine acts as a stimulant to the nervous system, and its mild action may help to prevent a feeling of fatigue. However, it is also a weak diuretic, which stimulates the production of urine by depressing secretion of anti-diuretic hormone. The suggested maximum daily intake is 300mg.
Tea does contain caffeine, however significantly less than coffee. A typical cup of Black Tea contains around 50mg per 190ml cup compared to up to 150mg in a coffee. Green Tea contains even less caffeine, typically around 25mg per cup, with White Tea containing even less at an average of 20mg.
Over the past decade or so we have become far too used to popping into Starbucks for a Skinny Latte or a Double Espresso on a regular basis without thought for the amount of caffeine we are consuming. This puts undue stress on the body and the mind and we are slowly beginning to move towards a more health conscious society in which Tea will play an important role once again.
Recently a panel of experts, which included internationally renowned nutritionists and biochemists, identified tea drinking as being hydrating rather than dehydrating and something that, due to its relatively low caffeine content, was mood enhancing yet had no negative effect on sleep quality or duration.
Re-hydration
Up to 70% of our body is water and it is therefore important to replace fluids that are lost through day-to-day activities. The suggested daily intake of water is 2.5 litres.
Due to the low caffeine levels found in Green Tea and White Tea, they would not be classed as being diuretic and can be drunk throughout the day all of which will count toward your daily intake of fluids.
Other Effects of Caffeine
Caffeine increases the risk of low birth weight and spontaneous abortion increases with increasing maternal caffeine intake during pregnancy. The Food Standards Agency advises that caffeine intakes above 300 mg/day shows a plausible association with low birth weight and spontaneous abortion, given the available evidence from studies. For caffeine intakes of 150 to 300 mg/day there is less evidence for an association.
(Food Standards Agency. Statement on the reproductive effects of caffeine. October 2001, COT Statement 2001/06)
Intake of 300 mg/day caffeine is equivalent to around four cups of instant coffee, two cups of freshly ground coffee, about six cups of Black Tea and 12 cups of Green Tea (assuming average caffeine contents).
In men, it has been shown that caffeine reduces rates of sperm mobility, which may account for some findings of reduced fertility.
Caffeine has also been associated with bladder cancer.
(Clavel J, Cordier S. Coffee consumption and bladder cancer risk. International Journal of Cancer 1991)
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