My actual green tea: Tokujyou Sencha (Tenkaichi)

Made from the softest young leaf tips and medium steamed (nakamushi).  
This delicate Sencha tea is one of the finest teas available in Japan.  
Recommend only for the experienced tea drinker, this tea should be brewed for a short time between 70 and 80 degrees celsius.

How much daily green tea?

Like black tea, green tea comes from the Camellia sinensis plant. The difference between them is green tea is made with unfermented leaves, while fully fermented leaves comprise black tea. Fermentation reduces the leaves' concentration of natural antioxidant compounds, or polyphenols, making green tea higher in antioxidants than black. The polyphenols in green tea appear to be more potent antioxidants than vitamin C, according to the University of Maryland Medical Center, and drinking it in moderation may benefit your health.

Catechins

Green tea contains six different types of polyphenols from the catechin family. The most active and widely studied of these is epigallocatechin gallate, or EGCG, a powerful antioxidant compound that also has antibacterial properties, according to authors of a "British Journal of Pharmacology" article published in 2013. They also noted that drinking green tea may ward off viral infections, such as influenza, hepatitis and herpes simplex, and may offer antifungal and antibacterial benefits, preventing a wide variety of diseases.

Cardiovascular Benefits

A high dose of antioxidants prevents free radicals from damaging your cells, protecting you from illness and premature aging. Drinking green tea may help keep your blood sugar and cholesterol low, making it a beneficial beverage for diabetics and people at an elevated risk for heart disease. It also may prevent atherosclerosis, or hardened arteries, according to Brazilian researchers who published a study in "Nutrition Research" in 2012. The research team found mice that drank water infused with a low dose of green tea extract for four weeks experienced significant improvements in atherosclerotic lesions and vascular reactivity, compared to mice that drank plain water. Higher concentrations of green tea extract were less effective than lower concentrations.

Cancer Prevention

In countries where green tea consumption is high, cancer rates tend to be low. Although research has yielded mixed results, some studies have indicated a link between green tea and a reduced risk of some types of cancer. Researchers from a study published in "Biomedical Research" in 2009 treated bladder cancer cells with green tea extract and found its catechin agents significantly inhibited the cells from growing. Green tea also may treat and prevent cancers of the pancreas, skin, breast, stomach, ovaries, esophagus, lungs and prostate.

Daily Intake

The potency of green tea varies from brand to brand, as does the potential for toxicity from excessive use. An overdose of green tea can lead to liver damage and other unpleasant side effects. To maximize the health benefits of green tea safely, the UMMC recommends drinking 2 to 3 cups daily, giving you 240 to 320 milligrams of polyphenols. If you take green tea extract supplements, 100 to 750 milligrams per day is recommended. Opt for caffeine-free products when possible. Because few studies have been done on green tea's effects on children, it is safest not to give it to them.

Source:  http://healthyeating.sfgate.com/green-tea-good-much-can-drink-daily-8620.html

The Most Common Types of Japanese Tea

Sencha Is the most common type of Japanese Green Tea and is brewed and served on a daily basis in most Japanese homes.  Sencha is steamed and rolled soon after it is harvested.

Fukamushi Sencha Fukamushi Sencha is the same as Sencha but it is steamed two or three times longer.

Other than Sencha, there are many kinds of Japanese Teas.  Below are some more common types of tea.

Gyokuro Gyokuro is made from from "Shinme" the first flush of tea leaves, and is shaded from sunlight for about 20 days before it is harvested and processed.  Gyokuro is the highest quality tea available.

Tencha Tencha is of the same class as Gyokuro and is also kept shaded from the sunlight before harvesting.  The main difference is that Tencha is not rolled.

Matcha Match is a fine powder made from Tencha and is dissolved in hot water rather than brewed like Sencha Teas. Matcha is recognized mostly for its use in the "Tea Ceremony".

Additionally, there is Kabusecha which is made from the second flush of leaves and is shaded from sunlight for 5 to 15 days before harvesting.

Bancha After the second flush of tea leaves are harvested, the tea plant continues to grow. Bancha tea is made from the later flushes of more firm leaves and stems. It is a coarse tea. The lower quality of Bancha makes it less expensive than Gyokuro and Sench. Bancha is also a popular and commonly served tea.

Houjicha Houjicha is roasted after it is dried.  It is made from the remains of Bancha.  Houjicha is brown in color.

Genmaicha Genmaicha is a blended tea.  It is made with Bancha, dry roasted brown rice and popcorn rice.  It has a distinct and fragrant aroma.

Kukicha Kukicha also called "stem tea" is actually what remains after sifting Gyokuro and Sencha.  It has a light sweet taste and is very mild.  It is often served with traditional Japanese snacks.

KonachaKonacha is a powdered tea and is usually made into tea bags.  It is often served in Sushi restaurants.

Source: http://www.japanesegreenteashops.com/teatypes.html