Properties: Bitter, sweet, cold

Meridans Entered:
Primary: Stomach, Heart and Lung

1. Dispels Wind-Heat and clears the head and refreshes the mind
   Dizziness and vertigo
   Headache
2. Alleviates Thirst and promotes urination
   Agitation and thirst
   Prevents the drying, dispersing and ascending nature of diaphoretic herbs from harming the body
3. Resolves Food Stagnation and alleviates diarrhoea
   Nausea, vomiting, indigestion and diarrhoea
   Damp-Heat dysentery
   Greasy Food Stagnation
   Obesity
4. Resolves Toxicity
   Sores and boils
   Topically on inflammation or hot swelling injuries (tannins are also astringent and so can stop bleeding)

Suggested Daily Dosage: 3-12g in decoction, but usually infused or added near the end.

Cautions: Avoid in insomnia. Leave 1 hour between taking iron supplements.

Interactions:

• Iron supplements: Tannins and oxalate in tea bind to free iron from plant sources reducing uptake by 70-80%.
• Folic acid: Decreases folate blood concentration.
• CNS stimulants: The caffeine present can enhance the effects of other nervous system stimulants such as amphetamines, cocaine and ephedrine (Ma Huang).
• Bortezomib: Polyphenols can inhibit the effects of this anti-cancer drug for myeloma. Not generally an issue when taken as a drink but can be when taken as a supplement.
• Anti-coagulants: Slows blood clotting, possibly by inhibition of thromboxane synthase, so may have additive effect with warfarin, heparin, aspirin and NSAIDs.
• Calcium channel blockers: May work in a similar method to reduce blood pressure and so have an additive effect on these medications.
• Antidiabetic drugs: Lowers blood sugar so may have additive effect on medications that also lower blood sugar.
• Recommended to stop 2 weeks before surgery due to stimulation of CNS and source of vit. K, antioxidant which may antagonise actions of warfarin. It may also cause arrhythmias and requires caution in renal and thyroid disease and insomnia (Ang-Lee, Moss & Yuan, 2001; Yilmaz & Çifci, 2018).

• Caffeine
  Xanthine alkaloid that acts as a central nervous system (CNS) stimulant.
• L-Theanine
  Neuroprotective agent that is being trialled for ADHD.
• Theophylline
  Alkaloid derivative of xanthine that is a phosphodiesterase inhibitor used in therapy for respiratory diseases such as chronic obstructive pulmonary disease (COPD) and asthma.
• Theobromine
  The principle alkaloid in the cacao bean responsible for its bitter taste but also present in trace amounts in tea. It is a xanthine alkaloid that is used as a bronchodilator and as a vasodilator via suppression of the vagus nerve. Despite being almost identical to caffeine, it has much less effect on the central nervous system with practically no stimulant properties. It was formerly used in the treatment of angina pectoris and hypertension.
• Epigallocatechin-3-gallate
  Tannin and phenolic antioxidant catechin under study as a potential cancer chemopreventive agent and apoptosis inducer. It is present in much higher doses in green tea due to the pan frying processing that stops it degradation through oxidation via polyphenol oxidise enzymes. It is also marketed as a weight loss supplement. High levels, over 800 mg/day (equivalent to 7-8 cups of tea), has been linked to liver toxicity when taken as a supplement, but no reports have been made when using the raw herb. It is often marketed as "Green Tea Extract" suggesting safety due to familiarity.
• Epicatechin gallate gallate
  Antioxidant polyphenol catechin tannin.
• Epigallocatechin
  Antioxidant polyphenol catechin tannin.
• Epicatechin
  Antioxidant polyphenol catechin tannin.
• Quercetin
  Polyphenolic flavonoid with many purported health benefits ranging from antiproliferative effects to preventing cardiovascular disease, hypercholesterolemia, rheumatic diseases, infections and cancer but has not been shown to be effective in clinical trials for any medical condition.

Notes:

A quote attributed to Tien Yiheng, 8th century Chinese sage, says:

"Tea washes away the noise of the world."

However, there seems to be no information on the verified sources of this quote or on the life and history of any Tang dynasty figure with this name that I could find, just the quote reproduced on blogs and web pages.

Tea did undergo a revolution in popularity during the Tang dynasty though, with poems being written about tea and even Lu Yu writing the world's first monograph on tea, the "Classic of Tea" in 780.

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Tang Dynasty poet Lu Tong 盧仝 (Yu Chuan Zi 玉川子) wrote a poem called The Seven Bowl of Tea, in which he compared drinking tea to the stages of enlightenment, demonstrating the spiritual link that was forming between tea and ceremonial religion at this time:

Lu Tong's Seven Bowls of Tea (七碗诗 卢仝（唐. 790~835）):

The first bowl moistens my lips and throat; 一碗喉吻潤，
The second bowl breaks my loneliness; 二碗破孤悶，
The third bowl searches my barren entrails but to find 三碗搜枯腸，
Therein some five thousand scrolls; 惟有文字五千卷，
The fourth bowl raises a slight perspiration 四碗發輕汗，
And all life's inequities pass out through my pores; 平生不平事盡向毛孔散，
The fifth bowl purifies my flesh and bones; 五碗肌骨清，
The sixth bowl calls me to the immortals. 六碗通仙靈，
The seventh bowl could not be drunk, 七碗吃不得也，
only the breath of the cool wind raises in my sleeves. 唯覺兩腋習習清風生。
Where is Penglai Island, Yuchuanzi wishes to ride on this sweet breeze and go back. 蓬萊山，在何處，玉川子乘此清風欲歸去。

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A cream with 10% green tea extract (Verengen, Catephen) has been recommended by NICE as a treatment for external genital and perianal warts (NICE, 2015) and may be effective in plantar warts too (Meloni & Milani, 2018).