The risks associated with green tea are the same as those associated with any other kind of tea (common black tea, White Tea etc.) and are primarily due to the content of caffeine and tannin. The contraindications may vary with the percentage of caffeine and tannins in it. Most people might be familiar with these adversities, but it is still important to review and summarize the components responsible, as well as the associated risks.
The oldest tea producing region in Japan is Uji, located near the former capital of Kyoto. It is thought that seeds sent by Eisai were planted in Uji, becoming the basis of the tea industry there. Today, Japan's most expensive premium teas are still grown in Uji. The largest tea producing area today is Shizuoka Prefecture, which accounts for 40% of total Japanese sencha production. Other major tea producing regions include the island of Kyushu and the prefectures of Shiga, Gifu, and Saitama in central Honshu.
Because matcha is prone to clumping (that’s why you’ll see instructions to sift it before whisking in the water or milk), you’ll want to take the same precaution in your baking experiments: Saffitz suggests combining the matcha with other dry ingredients like sugar or flour to avoid bitter lumps in your dough or batter. And use it sparingly, she suggests: Even a few teaspoons can create an intense flavor (and color).