What is tea?
The tea plant is a large evergreen shrub growing up to 8 meter high, but normally clipped to 1.5 meter to facilitate harvesting. The tea plant has glossy dark green leaves. The white tea flowers are formed on short stalks. The tea fruits are smooth and flattened capsule with three seeds.
Parts usedOnly the tea leaves are used. The young, light coloured leaves which grow at the top will produce the best tea.
Phytochemicals
These are typical phytochemicals found in tea: epigallocatechin gallate,
flavonoids,
tannins, caffeine,
polyphenols, boheic acid, theophylline,
theobromine,
anthocyanins,
gallic acid.
Benefits of tea
Because the tea tannins can bind with proteins, tea is used for its anti-diarrhoeal effect. The tannins have also antioxidant, diuretic and anti-cancer activity.
Tea seems to inhibit the absorption of cholesterol.
The best know effect of tea is the stimulating effect caused by caffeine. Caffeine affects adensine receptors and blocks the enzyme phosphodiesterase.
Antioxidant
The high levels of flavonoids in tea can protect our cells from oxidative damage by eliminating free radicals. Studies have shown that after consumption of green and black tea the antioxidant capacity in the blood increases. This enhanced blood antioxidant potential reduceds oxidative damage to molecules such as DNA and lipids.
Improves abdominal fat oxidation
Studies suggest that green tea catechins improve abdominal fat oxidation and may have a favourable effect on body composition. Studies with rodents have demonstrated that tea catechins increase fat oxidation and reduce dietary fat-induced weight gain.
Other facts
Green tea and black tea are the same plant. The difference is that during the tea production process only tea leaves for black tea undergo a fermentation process. Green tea is heat treated, fermented and dried. Black tea is rolled, fermented and then dried. This fermentation process changes the colour from yellow green to reddish brown. This fermentation also changes the composition of the phytochemicals: part of the polyphenols will oxidize. Green tea will therefore contain more antioxidant phytochemicals then black tea.
There are different myths about the discovery of tea. In one myth, the Gautama Buddha discoverd tea, when a tea leaf fell in his cup one day when he was meditating in a garden.
Other names
Green tea, black tea
Research Reviews
Abstracts
| 
