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 and activator of mitochondrial biogenesis via activation of AMPK, calcium, cAMP and PGC-1α pathways, protecting against metabolic and neurodegenerative stresses (Yamada et al., 2022; Vaughan et al., 2012).
• L-Theanine
  Amino acid that promotes relaxation and alpha brain waves and with neuroprotective properties. It smooths out the caffeine spike, which can feel calming or even sleepy. It has been trialled for ADHD (Kahathuduwa et al., 2020; Lyon et al., 2011) and is often used as a supplement but evidence is limited and is not yet recommended as a replacement for medication (Dashwood & Visioli, 2025). It is almost completely destroyed by oxidation meaning that black tea tends to have a stronger stimulant effect.
• 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 with antioxidant, anti-inflammatory, anti-microbial and chemopreventive properties that suggest it might be useful to inhibit the growth of cancer cells, prevent tooth decay, reduce inflammation, and protect neurons from damage (Alam et al., 2024). 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 (Henderson, 2022). It is often marketed as "Green Tea Extract" suggesting safety due to familiarity.
• Epicatechin gallate
  Antioxidant polyphenol catechin tannin.
• Epigallocatechin
  Antioxidant polyphenol catechin tannin.
• Epicatechin
  Antioxidant polyphenol catechin tannin. It is structural analogue snd mimic of 11-Β-OHP (11-Β-hydroxypregnenolone), a steroid that induces mitochondrial biogenesis (McDonald et al., 2020).
• 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:

Tea underwent a revolution in the Tang dynasty with Lu Yu writing the world's first monograph on tea, the "Classic of Tea" in 780, the world's first comprehensive treatise on the origins, cultivation, tools, and methods of drinking tea.

During the same dynasty, the poet Lu Tong 盧仝 (Yu Chuan Zi 玉川子) also wrote a poem called The Seven Bowl of Tea, in which he compared drinking tea to the stages of enlightenment, forging the spiritual link between tea and ceremonial religion at this time:

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

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

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Tian Yiheng, a Ming dynasty (16th century) scholar and poet, is famous for saying:

"One drinks tea and forgets about the clamour of the world."

During the Ming dynasty, tea was representative of a tasteful lifestyle, close to nature, aspired to by the literati (Jiang, 2023).

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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).