According to Eisai (*1), who brought Buddhism to Japan in the 12th century and wrote Japan's first book about tea, green tea is a precious medicine for health and long life.

Green tea is rich in natural elements and nutrients that are good for health.

(*1) Eisai was a Buddhist monk who studied in China and India. He brought Buddhist culture and tea culture to Japan.

(unit:g)	Tannin (Catechin)	Caffeine	Theanine/ Amino Acid	Fat	Carbo -hydrate	Fiber	Ash Content
Gyokuro	10.0	3.5	29.1	4.1	43.9	11.1	6.3
Sencha	13.0	2.3	24.5	4.7	47.7	10.6	5.0
Houjicha	9.5	1.5	18.2	4.8	39.2	18.7	5.5
Matcha	10.0	3.2	30.6	5.3	38.5	10.0	7.4
(per 100g of tealeaves)

	Vitamin A (μg)	C (mg)	E (mg)	B1 (mg)	B2 (mg)	Niacin (mg)
Gyokuro	21,000	110	16.6	0.30	1.16	6.0
Sencha	13,000	260	68.1	0.36	1.43	4.1
Houjicha	6,700	44	-	0.10	0.82	5.6
Matcha	29,000	60	28.1	0.60	1.35	4.0
(per 100g of tealeaves)

Catechin (Tannin)

Catechin, also called Tannin, is a bioflavonoid that has both antiviral and antioxidant qualities. It helps to prevent cancer by inhibiting the growth of cancer cells. Catechin also has many positive cholesterol-lowering effects. It helps to clear blocked veins and arteries, allowing your blood to flow more smoothly. Some studies show that Catechin may help prevent strokes, heart attacks, blood clots and even heart disease. Amazingly, Catechin also protects the entire body from oxidative damage due to free radicals and other toxins in our environment.
Tea leaves create Catechin to protect themselves from ultraviolet rays. So although all Japanese teas contain Catechin, those grown in full sunlight such as Sencha have the most Catechin.
Catechin is extracted best in water with a temperature of over 167 - 176F (75 - 80C).

The following is a list of the beneficial effects of Catechin:

• Removing free radicals (activated oxygen)
  Free radicals (activated oxygen) are powerful oxidizing agents in the body which are known to cause a wide variety of diseases, aging, and wrinkles. Free radicals increase by overexposure to ultraviolet rays, aging, smoking, and too much drinking. If you want to remove free radicals that have been created in your body, you may do this by consuming foods that have strong antioxidant properties. Catechin and Vitamin C are well known antioxidants. Japanese green tea contains both Catechin and Vitamin C. It is beneficial to drink Japanese green tea to remove these harmful free radicals.
• Reducing cholesterol
  Too much cholesterol is known to cause arteriosclerosis, myocardial infarction (heart attack), and cerebral infarction (stroke). But not all cholesterol is bad or unhealthy. LDL cholesterol is bad and HDL cholesterol is good. Too much LDL cholesterol can cause cells in the body to oxidize and cause arteriosclerosis. Catechin, which is found in Japanese green tea, blocks the formation of bad LDL cholesterol and therefore is helpful in preventing arteriosclerosis. Not only does the Catechin in Japanese green tea prevent bad LDL cholesterol from forming, but it increases good HDL cholesterol levels in the body as well.
• Reducing fat
  Many studies have shown that ingesting Catechin promotes healthy energy consumption in the body of human beings and animals - and reduces fat in the body and digestive system. It has also been reported that Catechin absorbed into the blood stream reaches cells in the liver and works to promote fat metabolism.
• Antibacterial and sterilizing
  Catechin has strong antibacterial and sterilizing effects on germs and bacteria. It has even been found to have the effect of sterilizing germs (NRSA) that cause infections in hospitals - so Catechin is beneficial to ward off infection and sickness in this way as well.
• Antiviral
  Studies have shown that Catechin can also prevent viral infections. Gargling with Japanese green tea has been shown to prevent influenza and the common cold and also helps to relieve symptoms of influenza and the common cold such as sore throat, cough, and nasal congestion.
• Preventing the influenza infection
  Hiroshi Yamada, doctor of internal medicine at Shizuoka General Hospital and professor of medicine at Shizuoka University, recently published a study regarding the effectiveness of Catechin against the new influenza (2009, H1N1 type). Through his research experiments, he proved that gargling with Japanese green tea can help to prevent the influenza infection. It is said that the positive effects of Catechin against influenza is the same with both the new influenza (2009, H1N1 type) and seasonal common influenza. In addition, it prevents the influenza infection more to ingest green tea, because Vitamin C and the other nutrients in Japanese green tea work together with Catechin. So, both gargling and drinking Japanese green tea are recommended.
• Moderating allergies
  Catechin has an effect of moderating allergies (including airborne pollen/mold allergies and dermatitis). It is recognized that Catechin moderates the symptoms of allergies including itching and sneezing.
• Oral care
  Catechin is an effective deodorant and general sterilizing agent. A cup of Japanese tea after a meal prevents the growth of germs, which cause periodontal disease and halitosis (bad breath).
• Preventing cavities
  Catechin is effective in preventing dental cavities. Catechin prevents existing cavities from becoming larger by balancing the enzymes found in the cavity area. By reducing harmful acids in the mouth which can destroy the tooth enamel, Catechin also works to protect the enamel and keep your teeth healthy and strong.

Theanine (Teanin)

Tea is the only plant that makes the amino acid Theanine, also known as Teanin or L-Theanine. Theanine stimulates alpha brain waves, which are associated with a relaxed but alert mental state. It helps relax the mind, allowing one to focus on the task at hand. Catechin is bitter and Theanine is sweet. These two elements create a perfect balance of taste.
Controlled experiments have shown that Theanine has a positive effect on the mind and improves memory by increasing Dopamine levels. The experiments also show that alpha brain waves increase 40 minutes after consuming Theanine. People can take advantage of their full mental capabilities when they are relaxed. So try a cup of green tea 40 minutes before work or study!
You might wonder how a cup of green tea, which contains so much caffeine, can be relaxing. The answer is Theanine. Theanine tempers the effects of caffeine, which can cause nervousness or excitability (as you might find with coffee) and works to relax the mind. So, although much caffeine is contained in green tea, green tea does not cause nervousness or excitability becaus of Theanine.
Much Theanine is found in tea leaves of Ichibancha (the first pick of the year) and Karigane (made from the stems of high grade tea). Gyokuro and Matcha are especially rich in Theanine because the tea leaves are grown in the shade before harvest. Theanine is equally extracted both in low and high temperatures.

Vitamin C

Vitamin C, Catechin, and Vitamin E work together to enhance immune function. These three nutrients also help to make your skin more beautiful by reducing blemishes, wrinkles and sun damage. Vitamin C found in green tea is water-soluble, and the heat used in brewing tea does not reduce its potency.

Caffeine

The mild caffeine in green tea has been found to increase cognitive performance, alertness, and energy. It can also help with weight loss through its stimulating and mild diuretic effects. The green teas with the highest caffeine content are Matcha, Gyokuro and Sencha. Houjicha (Bancha) and Genmaicha have the lowest caffeine content.

Bioflavonoids

The bioflavonoids found in green tea help to keep your teeth and gums healthy. You can gargle with green tea after brushing your teeth to kill germs and prevent bad breath.

Minerals

Tea is rich in minerals, including manganese, potassium and calcium, which help to alkalinize the blood, regulate the heartbeat, and build strong teeth and bones.

With all Japanese teas (Gyokuro, Sencha, Genmaicha, and Houjicha) except for Matcha, you can ingest large amounts of the beneficial constituents by brewing three times. It is said that 30% to 50% of the constituents are extracted into water by brewing tea leaves three times.

Matcha is ground into powder and completely dissolved in water when brewed (prepared), therefore you drink the whole constituents of the tea leaves and ingest all of the healthful nutrients without throwing away the leaves as one does with other teas: Gyokuro, Sencha, Genmaicha, and Houjicha. Besides, by drinking Matcha you can also ingest oil soluble constituents (Vitamin A, Vitamin E, Beta-carotene, etc.), which are not extracted into water when brewed.

To brew one cup of tea (Gyokuro, Sencha, Genmaicha, and Houjicha), about 3 to 4g (0.11 to 0.14oz) of tea leaves are used. To prepare one bowl (cup) of Matcha, about 2g (0.07oz) of tea leaves are used. So, if you are interested in ingesting constituents efficiently, you can most efficiently ingest constituents by drinking Matcha, more so than with other teas.

Even after teatime, used tea leaves can benefit your daily life!

Deodorizer

Green tea leaves have an amazing deodorizing effect. For example, you can burn dried used tea leaves as incense. The smoke will eliminate odors and make your room smell fresh. You can also put dried used tea leaves in your shoes to remove bad odors. Odors on cooking equipment like cutting boards and cooking pots can be removed by wiping them with damp used tea leaves.

Antirust

Wiping a steel pot or knife with used tealeaves can prevent the item from rusting. Tannin, an ingredient of green tea, makes an anti-rust coating on the surface of steel.

Antiseptic

Tea leaves have an antiseptic and astringent effect. You can gargle with green tea to kill germs or use as a topical antiseptic or astringent to keep your skin beautiful and healthy.

Traditionally, Japanese people used cloth soaked in Houjicha as baby wipes to keep the baby's skin clean and soft.