Tea Plant - Camellia sinensis

Common Names: Tea plant, Tea shrub, Camellia sinensis, Tea, Chá, Thé, Thee, Cha, Green tea plant, Black tea plant, White tea plant, Oolong tea plant, Chashu, International: Camellia sinensis (Latin, botanical name), Chinese tea plant, Assam tea, Japanese tea plant

Latin Name: Camellia sinensis (Thea sinensis)

Origin: Africa, Asia, Australia, Europe, South America, North America

Short Introduction

The tea plant can be grown as a shrub or tree in tropical and subtropical zones, from lowland areas up to high elevations above 2,000 meters. While high-altitude varieties produce fewer and smaller leaves, their harvest is typically of higher quality. Tea is propagated from seeds or cuttings, often started in nurseries and transplanted after half a year. Cuttings are moved after rooting, usually about eight months later. In suitable climates, it's advisable to repot annually. Pruning may begin after two years, and the first harvest is possible after three years of growth. The tea plant is generally low-maintenance, tolerating varied conditions but requiring consistent humidity throughout the year—overwatering should be avoided as roots are susceptible to rot. Tea prefers loamy-sandy soils (not calcareous); in cooler climates, peat moss is a good substrate. Tea plants grow best in partial shade, typically achieved by planting under taller trees. In temperate regions, overwinter tea plants indoors; in spring, they resume growth at 10–12°C and may be moved outdoors for the summer. Once the plant is well-branched and bushy, it's ready for harvest—collect the three youngest leaves (tips) and the nearest five or six leaves for the best tea. Fresh leaves can be used for green tea or dried and fermented for other types. Good quality tea plants may produce for up to 30 years, with optimal varieties yielding up to 3–4 harvests a year. Tea flowers from autumn to winter, grows in spring, and has another growth period at the end of July and August; flowering in cooler climates can occur after about 10 years.

Detailed Description

The tea plant is one of the world's most famous herbs, used to prepare the most beloved beverage across the globe.

Botanical Information

The tea plant, Camellia sinensis, is an evergreen that can take the form of a shrub or small tree, typically reaching heights between 5 and 30 meters (the tallest specimens are rare), though on plantations it is usually pruned to about 1 meter for easier harvesting. Its root system is strong, and the stem is slender. Leaves are 4–15 cm long and 1–10 cm wide, usually green to grey-green, deeply veined, with fine white hairs on the underside, and have a leathery texture. The flowers are 2–4 cm in diameter, usually white to creamy-yellow, resembling cherry blossoms, with 7 or 8 sepals, and are pollinated by insects; for indoor cultivation, pollination can be helped by a soft brush. The tea plant blooms from autumn through winter. Its fruit is a woody capsule containing three compartments, each with one to three seeds that resemble nuts.

Origin and Distribution

Camellia sinensis is native to East, South, and Southeast Asia, but today it is cultivated nearly worldwide in suitable climates, especially in tropical and subtropical zones, at a variety of elevations—even surviving mild frosts. The first documented evidence of tea cultivation dates back to around the 3rd century AD, but legends trace the origins of tea use even farther—possibly as far back as 3000 BC. The first comprehensive tea book was written by the Chinese tea master Lu Yu during the Tang Dynasty (7th–10th century). Over time, the popularity of tea grew rapidly not only in China, due to its unique taste and health benefits, but worldwide, becoming a prized trading commodity and leading to the spread of tea plantations in many regions. Today, the tea plant is cultivated under optimal conditions in China, Japan, India, Vietnam, Sri Lanka, the Caucasus, Java, Sumatra, Indonesia, South Africa, and even parts of Europe, such as Georgia and the Azores.

Usage / Dosage

The contents of fermented Camellia sinensis leaves, when taken in safe amounts, are believed to help prevent cancer growth, as shown in tissue culture studies. They also help reduce cholesterol levels in the blood. Polyphenols in the tea plant may help, through angiotensin regulation, to manage high blood pressure and lower blood sugar. Tannins support healthy digestion, may mildly reduce diarrhea, and help eliminate toxins from the body.

Theaflavins and their derivatives are still used as agents for improving blood flow and are supportive remedies for relieving asthma symptoms in both children and adults. Other key components include fluorides (which help prevent dental cavities) and manganese (important for energy metabolism and activating enzymes). The flavonoid complex in tea is thought to strengthen veins and is traditionally used as part of a regimen to relieve hemorrhoids, vein inflammation, varicose veins, and swollen lower limbs.

Tea leaf extract or infusion contains a wide spectrum of bioactive compounds. High catechin concentration in the extract can significantly reduce lipid radical levels in blood plasma (up to 50 times lower compared to Ginkgo biloba extract). Polyphenols, flavonoids, and anthocyanins in tea show up to double the antioxidant effect of the same dose of vitamin C, promoting a surge in natural antioxidant enzymes (superoxide dismutase and glutathione dismutase) and decrease in lipid radicals. The effect is so pronounced that green tea is officially recognized as an antioxidant by the European Medicines Agency (EMA).

Tea's bioactive compounds, especially caffeine, support fat metabolism and weight management. Caffeine acts as a cardiac stimulant and helps speed up bodily processes that increase fat usage for energy, especially when combined with physical activity. Overconsumption, however, is not recommended as tolerance develops with regular high intake.

Bioactive compounds in tea have recognized effects on stimulating the nervous system and metabolism. In appropriate doses, they can work as a natural remedy to reduce tiredness and address sleepiness and lethargy. Tea can also improve mental clarity, focus, and coordination. For athletes, caffeine and its derivatives can increase short-term athletic performance and endurance, with the effectiveness depending on individual weight and tolerance.

Lab studies with cell cultures have shown a significant antibacterial effect of tea's polyphenols against Streptococcus mutans, a key cause of tooth decay. This bactericidal effect, attributed to tea's antioxidant flavonoids, targets harmful bacteria while sparing beneficial ones, helping to maintain oral flora and prevent cavities—especially with regular brushing and sugar-free tea consumption.

The antioxidant effects of tea's polyphenols help reduce arterial hardening (atherosclerosis). Animal studies confirm that regular tea consumption protects the heart and blood vessels by preventing fat oxidation, lowering the risk of heart disease and myocardial infarction if additional risk factors are controlled.

Another important constituent is epigallocatechin gallate (EGCG), a flavonoid studied for its ability to regulate blood sugar after meals, apparently by blocking the alpha-amylase enzyme. Studies show that after exposure to Camellia sinensis, the activity of this enzyme drops by about 30%.

An alternative traditional use of tea's compounds includes the prevention of acne. Tea appears to block sebum production, exert a mild anti-inflammatory effect, and kill certain pathogenic bacteria responsible for acne. EGCG, in particular, is known for reducing cytokine migration and supporting immune function at inflammation sites, as well as reducing skin testosterone levels (a factor in male acne).

Some studies suggest that tea's compounds can stimulate bone formation and reduce bone resorption. Exposure to catechins on tissue cultures increases osteoblast activity and bone mineralization, thus strengthening the skeleton. This could be particularly beneficial for women during menopause, when the risk of bone loss is higher.

Preparation and Dosage

Tea varieties differ in preparation and dosage by type, cultivar, origin, and harvest time. Black tea is dried and extensively oxidized (fermented), while red, oolong (semi-fermented), white, yellow, and green teas are processed differently. Flavors, aromas, and colors vary widely, from strong, earthy Chinese Pu-erh (aged at least 3–5 years) to fresh Indian Darjeeling black teas, prized for their unique taste after the current year’s harvest.

Locally, tea is traditionally used for many ailments—green tea for cancer and cardiovascular prevention, dental and bone health, strengthening blood vessels, refreshment and fatigue reduction, lowering cholesterol and flu symptoms, and boosting short-term mental focus.

Traditional Chinese medicine uses tea as a bronchodilator for asthma, as well as for angina pectoris (and other coronary diseases) and peripheral vascular disorders. Some teas in China are also blended with herbs for type 2 diabetes treatment.

Active Compounds

Tea leaves contain 70–85% water; in dried form, about one third consists of tannins, 1–5% alkaloids (mainly caffeine), essential oils, vitamin C, and up to 25% protein. The full spectrum of constituents is complex—tea leaves contain up to a thousand compounds, many of them still not fully described. The main components include polyphenols, amino acids (notably theanine, which provides a relaxing effect by stimulating alpha waves in the brain), enzymes, carbohydrates, methylxanthines (caffeine, theobromine, theophylline), pigments (chlorophyll, carotenoids), and minerals (fluorine, manganese, selenium, iodine, aluminum, sodium, nickel, arsenic). Essential oils in tea include linalool, linalool oxide, nerolidol, methyl salicylate, phenylethanol, benzaldehyde, hexenal, hexenol, and n-hexanal. Major polyphenols include flavonoids, flavanols (catechin, epicatechin, epicatechin gallate, gallocatechin, epigallocatechin, and epigallocatechin gallate), flavonols, isoflavones, anthocyanins, theaflavins, and thearubigins.

Traditional Dosage

Preparation and dosage of tea depend greatly on the type and intended use. For most teas, steeping for up to 2 minutes yields most of the caffeine, while 2–4 minutes extracts additional tannins. The best results come from using the correct utensils (teapot, water, cup, strainer, etc.), with porcelain often preferred for preserving flavor. Teapots are best cleaned with water rather than detergent, and ideally dedicated to tea only. Spring water at 60–90°C is generally used, with cooler water for green teas. The usual amount is 2–5g of tea leaves per brew (one small teaspoon is sufficient for a single serving).

Tea can be sipped throughout the day, ideally in smaller, high-quality, well-prepared servings across multiple cups, independently of meals (though interesting food pairings exist).