Native to the rain forests of the mountains of southern China, the use of tea leaf, in the form of an infusion, merges with the history of China, where the plant has been used in traditional medicine for more than 5,000 years. , to stimulate cognitive functions, treat digestive disorders, promote the elimination of water, alcohol and toxins, activate blood circulation, and treat high blood pressure.
Green tea contains thousands of bioactive ingredients, mainly provided by polyphenols, which play a key role in the prevention and treatment of many diseases, due to their antioxidant, anti-inflammatory, anticancer, anti-cardiovascular, antimicrobial, properties. anti hyperglycemic and anti-obesity.
A little history
If America offered cocoa, Africa coffee and Oceania kawa, it remains only to attribute the genesis of tea to Asia. In China, legend has it that Emperor Chen Nong, “king of remedies” having tested more than 300 medicinal plants, plausible inventor of acupuncture needles, is also the one who propagated the idea of boiling water before drink it. So over 5,000 years ago, Chen Nong was boiling his water when a light breeze loosened some leaves from the nearby shrub. These leaves fell into the boiled water and Chen Nong was surprised to discover an infusion to his taste and did not fail to notice the tonic and euphoric effects.
When Marco Polo entered China, tea had long been the popular drink of this vast country. In the time of Lao Tzu (5th century BC), it was used as a tonic for the body and the mind, to chase away sleep as well as to refine vision as such, but also inner perception, which ranked tea among the sacred substances.
Tea, more than just a pleasure drink :
In the Tibetan heights and southwest China, however, tea was food for millions of human beings. For example, in China the leaves were first steamed, crushed in a mortar, boiled with rice and milk, flavored with ginger and orange peel, while in Tibet, besides the tea beaten in a churn with salt and butter, tsampa was prepared, a porridge made of tea leaves cooked with roasted and ground barley. It was not just a matter of accommodation, such as adding spinach to butter, for the tchang, the butter tea, symbol of human blood, was regularly offered to a female deity ruling over war, disease and the death.
The tea ceremony :
Japanese communal rite, the tea ceremony, leads the host to accompany his guests towards the tea pavilion, away from the main accommodation. Fairly small, it is endowed with the essential and not the superfluous, in a unity that emerges without any of the objects present standing out from the others. In this place, “where everything combines to place the soul in a delicious silence”, the sobriety of the decor nevertheless responds to the purity of the water chosen for the tea.
Let us enter the tea room, a stripped monastic cell, in which silences reign supreme. The service follows a rigorous order, each holding the cup over which they are ecstatic inwardly, spinning it for a long time in their hands. And each one, one after the other, absorbs the “liquid jade scum”, the master, the host completing the tasting. Silent thanks flow, we praise, in words steeped in grace and economy, the tea service, conclusion of this “intense and active vigil in contemplative silence”.
Let us now mention some therapeutic virtues of green tea
Neuropsychic, cognitive and neuroprotective properties :
The tea leaf has neurostimulatory properties due to its theine content, which is none other than caffeine. In fact, as with guarana or mate, the caffeine contained in tea increases the release of acetylcholine or catecholamines, which improves cognitive activity (memory, attention, alertness, concentration).
Lipid-lowering and cardiovascular properties :
Rich in flavonoids, tea inhibits the oxidation of LDL cholesterol, an atherogenesis inducer, which contributes in particular to lowering the cardiovascular risk. It increases the production of nitrogen monoxide, and promotes arterial vasodilation, especially at the aortic level.
Antidiabetic and metabolic properties :
Green tea extract aids in the management of obesity by stimulating thermogenesis of brown adipose tissue, an activity that is found to be much greater than what can be attributed to its caffeine alone. Its thermogenic properties could reside essentially in an interaction between its content of polyphenols (of catechin type) and of caffeine, and the noradrenaline released by the sympathetic system.
Antimicrobial properties :
Tea extracts indeed exhibit antibacterial activity against several gram positive and gram negative bacteria. Taking tea at concentrations identical to those found in the drink (one “cup” of tea contains about 3 mg of dry matter per ml) therefore inhibits methicillin-resistant Staphylococcus aureus.
Anti-cancer properties :
The catechins in tea inhibit the proliferation of tumor cells, and also promote the destruction of leukemia cells. Several epidemiological studies seem to indicate a positive effect of the consumption of green tea and the reduction of the risk of certain cancers, in particular that of the endometrium, ovaries, breast and prostate.
What are the precautions to take when consuming green tea :
- The use of green tea is contraindicated in cases of progressive gastric or duodenal ulcers, cardiovascular pathologies (arterial hypertension, arrhythmia) and hyperthyroidism, apart from medical supervision.
- The consumption of green tea is not recommended for pregnant or breastfeeding women.
- This plant is also reserved for adults.
Precautions for use :
- Do not exceed the recommended amounts.
- Do not combine the intake of caffeine and ephedrine (risk of hypertensive surge and increased cardiovascular risk).
- Avoid the association of products rich in caffeine (coffee, guarana, yerba, mate, kola nuts, etc.); cumulative risk of the molecule.
- Daily caffeine dosages are 400-450 mg maximum for an adult.
- Also avoid taking tea in the evening; the presence of caffeine causes sleep disturbances and reduces the sedative effects.
- Be aware that caffeine increases the elimination of calcium and magnesium in the urine.
- Take care in people with weak liver.
Drug interactions :
- The caffeine contained in tea can indeed interact with a large number of synthetic drugs, in particular with certain antibiotics (such as quinolones), theophylline and bronchodilators, psychotropic drugs (MAOIs), anticoagulants and antiplatelet agents, psychostimulants (amphetamines, cocaine, ephedrine), diabetes treatments, diuretics, lithium, cimetidine, antacids, clozapine, alendronate and nicotine.
- The tannins in tea can decrease the absorption of iron from the intestinal mucosa.
- Take into account the contribution of vitamin K in tea in case of joint intake of anti vitamin K.
- Green tea may also limit the absorption of folic acid.
- XING L. et al. Recent Advances in the Understanding of the Health Benefits and Molecular Mechanisms Associated with Green Tea Polyphenols. J Agric Food Chem. 2019 Jan 30
- CAULI O. et al., Caffeine and the dopaminergic system, Behav Pharmacol., 2005
- HOOPER L. et al. Flavonoids, flavonoid-rich foods, and cardiovascular risk. A meta-analysis of randomized controlled trials, Am J Clin Nutr., 2008 Jul
- DULLOO A.G et al., Grenn tea and thermogenesis : interactions between catechin-polyphenols, cafeine and sympathetic activity, International Journal of Obesity, 2000
- HAMILTON-MILLER J.M., Antimicrobial properties of tea (Camellia sinensis L.), Antimicrob Agents Chemother., 1995 November
- TANG N.P. et al., Tea consumption and risk of endometrial cancer : a mataanalysis, Am J Obstet Gynecol., 2009 Dec
- ZHANG M. et al. Tea consumption and ovarian cancer risk : a case control study in China, Cancer Epidemiol Biomarkers Prev, 2002
- OGUNLEYE A.A et al. Green tea consumption and breast cancer risk or recurrence : a meta-analysis, Brast Cancer Res Treat, 2010 Jan