Tea leaves, from the plant Camellia sinensis, can be processed in different ways to produce green, black and oolong teas with different properties. Tea contains manganese, zinc, potassium and magnesium and no carbohydrates or fats.

Tea is rich in fluoride – the green tea variety containing about twice as much per cup as the black tea.

Tea does not contain tannin of the type obtained from tree bark but a class of chemicals called polyphenols, which are chemically similar but do not have detrimental effects. Some scientists believe they can even help ward off cancer.

Caffeine is present in tea leaf. It is very soluble in boiling water. Each cup contains about 40 milligrams of caffeine, less than half that found in coffee.
The forming of a cream or precipitate when tea infusion cools is a result of caffeine.

The pigment, Chlorophyll predominates in tea. During manufacture it undergoes biological decomposition. It is a big molecule and has got the same sort of parent structure as hemoglobin but differs as the latter is made up of Iron, while Chlorophyll is made up of Magnesium. During withering Chlorophyl loses its colour and decomposes giving Magnesium.

Polyphenols is made up of carbon, hydrogen and oxygen. Teas grown under heavy shade or in dull weather are found to have lower polyphenol content When tea leaves are ruptured during rolling, the polyphenols and oxidase mix and oxidation starts if oxygen is present.

In the tea legend, the Chinese were very aware of the medicinal properties of the leaf from the tea bush. The Tang Dynasty records show that tea was cultivated specifically for health enhancing reasons.

When tea was first introduced to Japan in AD800 it was recognized as beneficial to health. The Dutch and British introduced tea to their market through apothecary shops and, with publicity describing its virtues, in the coffee houses.

In the U.K some famous brands have connections with medicine: ‘Typhoo’ is the Chinese word for doctor; the ‘PG’ of ‘PG Tipps’ stands for pre-gestive; and the cooperative company’s ‘99’ tea comes from the form number of the prescription pads used by doctors.