A tea leaf consists of 77 percent water and 23 percent solid matter. Of the latter, about one-third is made up of water-soluble components – including amino acids, polyphenol (includes catechins), polysaccharides, and vitamin C – and two-thirds consists of insoluble components – including crude fibers, cellulose, vitamin E, and carotene.
Each components has its own good qualities, and some, particularly the catechins that generate the astringency of tea, have many other benefits. Some nutrients that are not extracted when tea is used s a cooking ingredient.
Water Soluble Components :
- Amino acids (theanine)
- y-Amino butyric acid
- Vitamin C, vitamin B complex
- Water – soluble dietary fibers
Catechins are related to flavonoids, have antibacterial and anti-oxidative functions, and are effective in reducing oxidation, inhibiting the spread of cancer and tumors, and lowering cholesterol levels in the blood. They also play a part in stabilizing blood pressure and blood sugar, resist, viruses, and have a deodorization function.
Caffeine: The caffeine content of tea leaves is three time higher in the top shoot than in the lower stalk. It is estimated that 1 pound (450 grams) of the leaves – sufficient to make 200 cups of tea – contain approximately 1/2 ounce (16 grams) of caffeine. However, the caffeine in green tea is supposedly milder than that in coffee. Caffeine counteracts fatigue and drowsiness, stimulates heart function, and also acts as a diuretic.
Polysaccharides: Effective in lowering blood sugar.
Fluoride: Protects the enamel of teeth and prevents cavities.
Vitamin B complex: Effective in regulating the metabolism of saccharine.
Vitamin E: Its effects include an anti-oxidation action and slowing of the aging process.
Vitamin C: Its effects include lessening stress and building up resistance to mild infections such as colds.
y-Amino butyric acid (Gava): Protects against hypertension.
Flavonoids: Their effect include strengthening the walls of blood vessels and preventing halitosis.
Theanine: One of several amino acids, which are responsible for the distinctive aroma and flavor of tea.