Everything You Need to Know About

Tea plant (Camellia sinensis)

Botanical family: Theaceae

Parts used: Leaves

Overview and Health Benefits

The subtle aroma of freshly brewed Camellia sinensis has long been a hallmark of cultural traditions and medicinal practices, enjoyed in the form of green tea or black tea. Revered for its potent polyphenol content, particularly catechins such as epigallocatechin gallate (EGCG), green tea in particular has gained recognition in herbal medicine for its wide-ranging health benefits. Black and oolong tea require partial fermentation of the leaves, but green tea is produced by steaming fresh leaves, which inactivates oxidising enzymes in the leaves and preserves polyphenol content. From enhancing cardiovascular health to offering protective effects against various forms of cancer, green tea is much more than just a comforting beverage—it's a potent ally in promoting health and longevity. The antioxidant properties of green tea’s bioactive compounds are central to its therapeutic effects, making it a valuable component in the prevention and management of chronic diseases.

Key Benefits:

Antioxidant Powerhouse
Cardiovascular Health
Cancer Prevention
Metabolic and Endocrine Regulation
Neuroprotective Effects
Antimicrobial and Antiviral Properties

Green tea is renowned for its high catechin content, especially EGCG, which significantly contributes to its powerful antioxidant activity. These compounds help neutralise free radicals, thereby reducing oxidative stress—a major contributor to chronic diseases and ageing. This antioxidant action is crucial for maintaining cellular health and preventing damage that could otherwise lead to conditions like cardiovascular disease and neurodegeneration (Lambert & Elias, 2010; Hajam et al., 2022; Vinson et al., 1995).

Regular consumption of green tea has been linked to improved cardiovascular outcomes. The catechins in green tea help lower blood pressure, improve lipid profiles, and prevent the oxidation of LDL cholesterol, a key factor in the development of atherosclerosis. Studies suggest that drinking green tea may reduce the risk of heart disease and stroke, highlighting its role as a cardioprotective agent (Sano et al., 2004; Sánchez et al., 2020; Vinson et al., 1998). Furthermore, green tea polyphenols promote hepatic detoxification pathways and protect against cardiac toxicity during chemotherapy (Sengottuvelu et al., 2008).

The potential anticancer effects of green tea are widely studied, with evidence suggesting that EGCG may inhibit cancer cell growth and metastasis (Yang et al., 2011). Green tea catechins interfere with cellular mechanisms of various cancers, including breast, prostate, and colorectal cancers, by promoting apoptosis and inhibiting angiogenesis, thereby reducing tumour growth and spread (Pastore & Fratellone, 2006; Demeule et al., 2002). Additionally, green tea has been shown to inhibit key pathways involved in tumour initiation, growth, and metastasis, such as NF-kappa B and VEGF, and to potentiate the effects of certain chemotherapeutic agents while protecting against their side effects (Lambert & Elias, 2010).

Green tea supports metabolic health by enhancing insulin sensitivity and glucose metabolism. These effects are particularly beneficial for individuals with or at risk of type 2 diabetes, as they help regulate blood sugar levels and reduce the risk of diabetes-related complications (Sánchez et al., 2020). Additionally, green tea’s thermogenic properties aid in weight management by increasing fat oxidation and improving lipid metabolism, making it a popular component of weight loss regimens (Hursel et al., 2011; Hodgson et al., 2013; Sánchez et al., 2020).

The neuroprotective properties of green tea, attributed largely to EGCG, include the potential to protect against neurodegenerative diseases like Alzheimer’s and Parkinson’s (Mandel & Youdim, 2004). Green tea polyphenols help reduce inflammation and oxidative stress in the brain, which are key contributors to neurodegeneration. Moreover, green tea has been shown to enhance cognitive function, possibly due to its effects on neurotransmitter regulation and the protection of neuronal cells from oxidative damage (Scholey et al., 2012).

Green tea has demonstrated significant antibacterial and antiviral effects (Steinmann et al., 2012). The catechins in green tea, particularly EGCG, are effective against a range of pathogens, including Staphylococcus aureus, Helicobacter pylori, and various viruses such as HIV, HPV, and influenza (Sugita-Konishi et al., 1999; Carneiro et al., 2016). These properties make green tea a valuable natural remedy for preventing and managing infections.

Safety

While green tea is celebrated for its numerous health benefits, it is important to approach its consumption with awareness of potential cautions and contraindications. Green tea contains tannins, which can inhibit iron absorption, making it advisable to leave at least two hours between consuming tea and iron-rich foods or supplements (Disler et al., 1975). The caffeine present in green tea, though moderate, acts as a stimulant and diuretic, which can be problematic for individuals sensitive to caffeine or those with anxiety disorders, insomnia, or certain cardiovascular conditions (Hodgson et al., 2013). Excessive intake of green tea, particularly in supplement form, can lead to adverse effects such as gastrointestinal discomfort, liver toxicity, and impaired iron absorption due to its high tannin content (Bonkovsky, 2006). Moreover, the caffeine present in green tea, although relatively moderate, can exacerbate conditions like anxiety disorders, insomnia, and certain heart conditions, and may interact with medications such as blood thinners, beta-blockers, and stimulants (Hodgson et al., 2013). Additionally, studies have shown conflicting evidence regarding the interaction between Camellia sinensis and certain cancer medications, suggesting that those undergoing treatment should seek expert advice (Schönthal, 2011). It's important to note that the risks associated with green tea or its active compound, EGCG, generally arise with very high doses, far above what is typically consumed in a daily diet (Schönthal, 2011). Green tea polyphenols have also been shown to inhibit the activity of certain drug-metabolising enzymes, which could alter the effectiveness of prescription medications, including chemotherapy agents and anticoagulants (Lambert & Yang, 2003).

Therefore, as with any herbal remedy, it is best to consult with a qualified medical herbalist before using green tea in significant doses for medicinal purposes, especially if you have a pre-existing medical condition or are taking any prescription medications.

Featured Products Containing Tea plant (Camellia sinensis)

Key Body Systems Tea plant (Camellia sinensis) relates to

Cardiovascular and Circulatory

Digestive System

Nervous system

Warming

Drying

Key actions

Antioxidant
Anti-inflammatory
Antidiabetic
Neuroprotective
Neuroprotective

Key uses

Improve mental alertness, cognitive function and mood
Fight oxidative stress
Relieve fatigue
Promote relaxation

Where to Find Tea plant (Camellia sinensis)

Camellia sinensis, the plant from which white, green, black, and oolong teas are derived, is a small, evergreen shrub belonging to the Theaceae family, a group known for its glossy leaves and showy flowers. Botanically, Camellia sinensis is characterised by its dark green, serrated leaves that are pointed and oval-shaped, with a waxy texture. The young leaves, which are typically harvested for tea production, are more tender and lighter in colour compared to the mature leaves.

Camellia sinensis can grow up to 2-3 metres in height if left unpruned, though it is typically kept shorter in cultivation to facilitate leaf picking. The bark of the shrub is smooth and grey, providing a subtle contrast to the vibrant leaves.

This plant thrives in the subtropical and tropical regions of Asia, particularly in areas like China, India, Sri Lanka, and Japan, which are renowned for their tea production – although in a changing climate, tea cultivation has now spread to other more temperate regions, including in the UK. It favours acidic, well-drained soils and flourishes in regions with high humidity and ample rainfall. The ideal temperature for its growth ranges between 10°C and 30°C, with elevations between 600 to 2,000 metres above sea level providing the best growing conditions, especially for high-quality tea.

Camellia sinensis shares this lineage with other Camellia species, many of which are cultivated for their ornamental flowers.

References

Balappanavar, A. Y. (2020). Tea and oral health. In G. Justino (Ed.), Tea - Chemistry and Pharmacology. IntechOpen. https://doi.org/10.5772/intechopen.80998

Bonkovsky, H. L. (2006). Hepatotoxicity associated with supplements containing Chinese green tea (Camellia sinensis). Annals of Internal Medicine, 144(1), 68-71. https://doi.org/10.7326/0003-4819-144-1-200601030-00020

Carneiro, B. M., Batista, M. N., Braga, A. C. S., Nogueira, M. L., & Rahal, P. (2016). The green tea molecule EGCG inhibits Zika virus entry. Virology, 496, 215-218. https://doi.org/10.1016/j.virol.2016.06.012

Demeule, M., Michaud-Levesque, J., Annabi, B., Gingras, D., Boivin, D., Jodoin, J., Lamy, S., Bertrand, Y., & Béliveau, R. (2002). Green tea catechins as novel antitumor and antiangiogenic compounds. Current Medicinal Chemistry - Anti-Cancer Agents, 2(4), 441–463. https://doi.org/10.2174/1568011023353930

Disler, P. B., Lynch, S. R., Charlton, R. W., Torrance, J. D., Bothwell, T. H., Walker, R. B., & Mayet, F. (1975). The effect of tea on iron absorption. Gut, 16(3), 193-200. https://doi.org/10.1136/gut.16.3.193

Hajam, Y. A., Rani, R., Ganie, S. Y., Sheikh, T. A., Javaid, D., Qadri, S. S., ... & Reshi, M. S. (2022). Oxidative stress in human pathology and aging: Molecular mechanisms and perspectives. Cells, 11(3), 552. https://doi.org/10.3390/cells11030552

Hodgson, A. B., Randell, R. K., & Jeukendrup, A. E. (2013). The effect of green tea extract on fat oxidation at rest and during exercise: Evidence of efficacy and proposed mechanisms. Advances in Nutrition, 4(2), 129-140. https://doi.org/10.3945/an.112.003269

Hursel, R., Viechtbauer, W., Dulloo, A. G., Tremblay, A., Tappy, L., Rumpler, W., & Westerterp-Plantenga, M. S. (2011). The effects of catechin rich teas and caffeine on energy expenditure and fat oxidation: A meta-analysis. Obesity Reviews, 12(7), e573-e581. https://doi.org/10.1111/j.1467-789X.2011.00862.x

Lambert, J. D., & Elias, R. J. (2010). The antioxidant and pro-oxidant activities of green tea polyphenols: A role in cancer prevention. Archives of Biochemistry and Biophysics, 501(1), 65-72. https://doi.org/10.1016/j.abb.2010.06.013

Mandel, S., & Youdim, M. B. H. (2004). Catechin polyphenols: Neurodegeneration and neuroprotection in neurodegenerative diseases. Free Radical Biology and Medicine, 37(3), 304-317. https://doi.org/10.1016/j.freeradbiomed.2004.04.012

Pastore, R. L., & Fratellone, P. (2006). Potential health benefits of green tea (Camellia sinensis): A narrative review. Explore, 2(6), 531-539. https://doi.org/10.1016/j.explore.2006.08.008

Sánchez, M., González-Burgos, E., Iglesias, I., Lozano, R., & Gómez-Serranillos, M. P. (2020). The pharmacological activity of Camellia sinensis (‎L.‎) ‎Kuntze‎ on metabolic and endocrine disorders: A systematic review. Biomolecules, 10(4), 603. https://doi.org/10.3390/biom10040603

Sano, J., Inami, S., Seimiya, K., Ohba, T., Sakai, S., Takano, T., & Mizuno, K. (2004). Effects of green tea intake on the development of coronary artery disease. Circulation Journal, 68(7), 665-670. https://doi.org/10.1253/circj.68.665

Scholey, A., Downey, L. A., Ciorciari, J., Neale, C., Moss, M. C., Gawrylowicz, J., ... & Stough, C. (2012). Acute neurocognitive effects of epigallocatechin gallate (EGCG). Appetite, 58(1), 414-418. https://doi.org/10.1016/j.appet.2011.11.016

Sengottuvelu, S., Duraisami, S., Nandhakumar, J., Duraisami, R., & Vasudevan, M. (2008). Hepatoprotective activity of Camellia sinensis and its possible mechanism of action. Iranian Journal of Pharmacology & Therapeutics, 7(1), 9–14. https://www.sid.ir/EN/VEWSSID/J_pdf/101020080102.pdf

Steinmann, J., Buer, J., Pietschmann, T., & Steinmann, E. (2012). Anti-infective properties of epigallocatechin-3-gallate (EGCG), a component of green tea. British Journal of Pharmacology, 168(5), 1059-1073. https://doi.org/10.1111/bph.12009

Sugita-Konishi, Y., Hara-Kudo, Y., Amano, F., Okubo, T., Aoi, N., Iwaki, M., & Kumagai, S. (1999). Epigallocatechin gallate and gallocatechin gallate in green tea catechins inhibit extracellular release of Vero toxin from enterohemorrhagic Escherichia coli O157. Biochimica et Biophysica Acta (BBA) - General Subjects, 1472(1-2), 42-50. https://doi.org/10.1016/s0304-4165(99)00102-6

Vinson, J., Dabbagh, Y. A., Serry, M., & Jang, J. (1995). Plant flavonoids, especially tea flavonols, are powerful antioxidants using an in vitro oxidation model for heart disease. Journal of Agricultural and Food Chemistry, 43(11), 2800-2802. https://doi.org/10.1021/jf00059a005

Yang, C. S., Wang, H., Li, G. X., Yang, Z., Guan, F., & Jin, H. (2011). Cancer prevention by tea: Evidence from laboratory studies. Pharmacological Research, 64(2), 113-122. https://doi.org/10.1016/j.phrs.2011.03.001

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Overview and Health Benefits

Key Benefits:

Safety