Ever since its first appearance in Asia, tea has been considered beneficial for the body. Its oldest references come from historians advocating its medicinal properties: at first tea was used in the form of a paste, as a poultice to combat rheumatism.
In the 21th century medical science allows us to understand scientifically the many benefits that tea drinkers have known empirically for over two thousand years.
There are three alkaloids present in tea: caffeine, theophylline and theobromine. These are organic substances that are found in all types of teas whatever its colour.
This is the main alkaloid in tea; it represents 2% to 3% of the dry leaf. It is important to realize that caffeine found in tea and coffee is one of the same molecule, the only difference being that it is proportionately more present in coffee.
The caffeine content of a tea depends both on the leaf used - the bud and the first leaf contain twice as much as Souchong leaves - and on the season of the harvest, since climatic variations influence the maturity of the leaf.
Some teas are therefore high in caffeine: new season crops, those with many buds; others are almost entirely bereft of caffeine: smoked teas and Wu Long (oolong) teas. Caffeine is a strong stimulant to the nervous system. Unlike coffee, the caffeine in tea is released slowly into the body. Because of this, it allows us to stay awake and alert without becoming hyper. This makes tea the ideal beverage to accompany exercise, both mental and physical.
Theophylline is present in much smaller amounts than caffeine. Its function is essentially one of vasodilatation, in other words it helps to dilate veins and blood vessels, improving blood circulation. This explains why tea, whether ice cold or boiling hot, is a refreshing drink: vasodilatation is one of the mechanisms that contribute towards the thermoregulation of the body's temperature.
Theophylline is also a respiratory stimulant.
This alkaloid, which is found in lesser quantities than the previous two, has a strong diuretic effect.
Tannins or polyphenols
Tannins in tea are similar substances to the tannins found in wine, both have very similar properties. It is easy to recognise a tea that is high in tannin by the astringency of the drink, which sometimes translates into bitterness if the tea has been over brewed: tannins are released slowly but in an ever increasing way, so that an overly long infusion considerably raises their Tannins in tea are similar substances to the tannins found in wine, both have very similar properties. It is easy to recognise a tea that is high in tannin by the astringency of the drink, which sometimes translates into bitterness if the tea has been over brewed: tannins are released slowly but in an ever increasing way, so that an overly long infusion considerably raises their concentration and makes the tea bitter.
Scientific research has revealed that polyphenols have an effect on bad cholesterol. Thus a daily intake of 5 cups of tea leads to a lowering, after a few months, of LDL-cholesterol (the "bad" cholesterol as opposed to HDL-cholesterol). Other studies have further explored this matter and have highlighted the effects of green tea in the prevention of cardio-vascular disease.
One digestive effect of polyhenols has been demonstrated: drinking green tea limits the absorption of fats during digestion. So a cup of tea taken at the end of a meal, about 40 minutes afterwards, will aid digestion by activating a process of fat elimination.
Numerous scientific theories pertaining to the antioxidizing effects of polyphenols have also been tested. Polyphenols, which are present in considerable quantities in green tea, play a vital role in the fight against the free radicals that are responsible for the aging of cells. One of the polyphenols in green tea - epigallocatechol gallate - is the object of very detailed scientific research into the fight against the development of cancerous cells.
At the present time, this research has been tested only on animals, and the same results still have to be proven for man in order to establish a link between tea consumption and the prevention of certain cancers.
Tea is a plant with a naturally high vitamin C content (about 250 mg per 100g of fresh leaves).Unfortunately, this is completely destroyed from the minute the tea is infused in water at a temperature above 30°C. Vitamin P: Tea contains a considerable amount of vitamin P, which increases capillary strength and shortens bleeding time.
B group vitamins:
Highly soluble in water, many B vitamins are to be found in a cup of tea. They contribute to the general good health of the human body, by kick-starting the metabolism, in other words the whole series of reactions taking place within our organic tissue: energy output, nutrition, assimilation…
Tea is rich in potassium and fluoride. The importance of fluoride in the fight against dental cavities is well known. On the other hand it is low in salt, which makes it perfectly suitable for salt-free diets.
All the properties and benefits of tea underlined here are dietary and not therapeutic recommendations. Drinking tea, in whatever quantities, should never be seen as part of the treatment for curing such or such a disease. But, regular tea drinking effectively contributes towards maintaining good health and to the prevention of some infections.