Japanese green tea contains potassium, vitamin C, caffeine, and tannin.

Type of tea Calories
Vitamin C
Infusion conditions
(Amount of tea leaves, water temperature & amount, brew time)
Matcha Tea leaves
324 2700 60 3.2 10.0
Gyokuro Tea leaves
329 2800 110 3.5 10.0  
Tea 5 340 19 0.16 0.23 10 g, 60°C/60 ml, 2.5 min.
Sencha Tea leaves
331 2200 260 2.3 13.0  
Tea 2 27 6 0.02 0.07 10 g, 90°C/430 ml, 1 min.
Tea 0 32 3 0.01 0.03 15 g, 90°C/650 ml, 0.5 min.
Hojicha Tea 0 24 Trace amount 0.02 0.04
Genmaicha Tea 0 7 1 0.01 0.01
Oolong tea Tea 0 13 0 0.02 0.03
Black tea Tea 1 8 0 0.03 0.10 5 g, 100°C/360 ml,
1.5 to 4 min.

Source: Standard tables of food composition in Japan, 2010 (Shokuhin Seibunhyo 2010), Yoshiko Kagawa (ed.).

Tannin Tannin is the source of tea’s astringency. It has been shown in many studies that the catechin component fights bacteria and lowers cholesterol.
Caffeine Caffeine is the source of tea’s bitterness. Although caffeine is a stimulant, its potency in green tea is somewhat offset by the presence of theanine, an amino acid which offers a calming effect.
Potassium Potassium helps to curb high blood pressure and enhances muscle function.
Vitamin C Green tea, especially sencha, contains a relatively high amount of vitamin C. Readily soluble in hot water, vitamin C is known for helping to maintain complexion, as well as for offsetting the harmful effects of alcohol and nicotine.
Theanine Theanine is an important amino acid found in Japanese green tea. It is responsible for its umami flavor, and also produces a calming effect on the body, helping to curb high blood pressure and regulate brain and nerve function.

The amount of theanine found in the different types and grades of green tea is shown in the table below.

Theanine—the source of umami flavor

Whether or not the tea is shade-cultivated greatly affects the amount of theanine it contains—theanine is the component that gives Japanese green tea its umami (full-bodied mellow sweetness). The shade-cultivated teas, matcha and gyokuro, are higher in theanine than sencha and bancha, which are not shade-cultivated.

Matcha / gyokuro tea group

During a period of about twenty days before harvesting, matcha and gyokuro tea plantations are completely shaded, so that the tea grows without direct exposure to sunlight.

Sencha / bancha tea group

Cultivated in open fields the entire time, sencha and bancha teas remain fully bathed in sunlight as they grow.

Type of tea Theanine
Matcha Higher-grade 抹茶上級 2,260
Medium-grade 抹茶中級 1,790
Lower-grade 抹茶下級 1,170
Gyokuro Higher-grade 玉露上級 2,650
Medium-grade 玉露中級 1,480
Lower-grade 玉露下級 1,340
Sencha Premium-grade 煎茶上級 1,980
Higher-grade 煎茶中級 1,280
Medium-grade 煎茶中級 1,210
Lower-grade 煎茶下級 612
Bancha     ---

Source: The Science of Tea (Cha no Kagaku), Keiichiro Muramatsu (ed.).

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