The subject of Tea and Health is mainly concerned with the various substances contained in different varieties of tea and how they affect the metabolism of the consumer.
Tea contains negligible amounts of protein and carbohydrate and is therefore not a source of primary nutrition. However, human metabolism requires thousands of other
substances which cannot be made or synthesised in the human body itself. These can either be found in sources of primary nutrition or in dietary supplements.
Tea contains many of these important substances, particularly anti-oxidant flavonoids as well as some vitamins. Green tea also contains some fluorine (which is good for
teeth) and theamine, a psychoactive substance which produces a soothing, stress relieving effect in the brain and improves cognition.
It should be remembered in any discussion of these substances that although their presence in a certain amount in a given type of tea is not difficult to determine, the vast
majority of experiments that are done to determine the biochemical properties of these substances are done in vitro (literally "in glass", i.e. in a laboratory experiment).
The possible effects of these properties are then tested for by taking samples from volunteers who have consumed the substance in question. Although there is a good match between
these types of experiments done for various types of teas, what exactly occurs in vivo (literally "in living", i.e. in the body) is still largely uncertain and a matter
of some debate.
We currently take the view that moderate consumption of green tea (and to a lesser extent good quality black tea) is beneficial to the health of the vast majority of people.
it may not be recommended for people on certain types of strong medication, but it certainly has far more benefits and far fewer side effects than the poor quality beverages that
are currently consumed on a daily basis in most western countries - particularly when these beverages are consumed with milk and sugar, and often with biscuits and low quality
confectionery also.
