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. Legends about tea, whether Chinese, Indian or Japanese, all show, in their own way, the stimulating and invigorating properties of tea. The Emperor Shen Nung, father of Chinese medicine and farming, states in his Medical Book that, "tea relieves tiredness, strengthens the will, delights the soul and enlivens the sight."
In the 20th century medical science allows us to understand scientifically the many benefits that tea drinkers have known empirically for over two thousand years.

 

Xanthics

There are three xanthics present in tea: caffeine, theophylline and theobromine.

These are organic substances that are found in all types of teas whatever its colour.

Caffeine
This is the main xanthic 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.

While this stimulating effect can cause a slight tendency towards insomnia in sensitive people it is very easy, on the other hand, to "decaffeinate" one's tea at home without altering the flavour: because the caffeine in tea is a constituent which is released in the first few seconds of infusion, just rinse the leaves with a first pouring of boiling water, leave for about thirty seconds and then throw the water away.

Theophylline
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, which is used in certain medicines for the treatment of asthma. However tea should not, under any circumstances, be considered as a remedy for this type of complaint.

Theobromine
This xanthic, which is found in lesser quantities than the previous two, has a strong diuretic effect. By stimulating renal circulation, it encourages evacuation though the urinary tract.