Products
Teas made from the leaves and buds of the tea plant are available, for example, in pharmacies, drugstores, tea specialty stores and grocery stores. They are one of the most consumed beverages in the world.
Stem plant
The tea plant from the tea shrub family (Theaceae) grows into an inmmergreen shrub or a tree. It is native to the border area of China and Burma and has been used for thousands of years. The two main varieties are:
- Camellia sinensis var. sinensis (China tea plant, small-leaved).
- Camellia sinensis var. assamica (Assam tea plant, large-leaf).
Medicinal drug
The leaves and buds of the plant are used as medicinal raw material, more rarely the stems. From them, the various types of tea are made. These include:
- Green tea, unfermented
- Black tea, fully fermented
- White tea, virtually unprocessed
- Pu-erh tea, microbially fermented, pressed, stored.
- Oolong, partially fermented
- Yellow tea, partially fermented
- Matcha, ground to powder green tea from Japan.
The plant parts contain enzymes that lead to oxidation of the ingredients. This process is called fermentation, but no microorganisms such as fungi and bacteria are involved. An exception is Pu-Er tea, which is microbially fermented. The different types of tea are created due to the different processing steps. The main ones are:
- Withering
- Steaming, roasting
- Rolling
- Drying, often also in the sun
- Ferment (oxidize)
Ingredients
The range of ingredients depends on the variety, cultivation and processing, among other factors. The main ingredients are:
- Methylxanthines: caffeine, theobromine, theophylline.
- Flavonoids, polyphenols, catechins (eg epicatechin, epicatechin-3-gallate, epigallocatechin, epigallocatechin gallate, EGCG), tannins.
- Theaflavins, thearubigens
- Amino acids (eg, theanine), proteins, enzymes.
- Aromatic substances, volatile compounds
- Minerals, vitamins
Effects
The teas have various health-promoting effects. In studies, they have shown antioxidant, anti-inflammatory, antitumor, antimicrobial, astringent, thermogenic and lipid-lowering properties, among others. Green tea has mild stimulant effects due to caffeine. However, the content is lower than in coffee, which is why teas are better tolerated.
Indications
Teas are consumed in the West mainly as health-promoting and mildly stimulating stimulants. They are also used medicinally, for example black tea for the treatment of diarrhea, headache or conjunctivitis.
Dosage
Teas are usually prepared as an infusion. For green tea should not be used boiling water, but only 70 to 90 ° C maximum. It is left to steep for only two to three minutes.
Contraindications
- Hypersensitivity
- Stomach or intestinal ulcers
- Cardiovascular diseases such as cardiac arrhythmias
- Hyperthyroidism (overactivity of the thyroid gland)
- Children
Interactions
Tannins can inhibit the absorption of drugs, such as tricyclic antidepressants or neuroleptics.
Adverse effects
Possible adverse effects of the tea include indigestion. Caffeine can cause various side effects and should not be overdosed (see there).
