Heat or boil water, but don’t let it completely boil and become too hot, as this can destroy some of the delicate compounds found in green tea leaves. The “ideal” temperature for brewing green tea is between 160 degrees Fahrenheit to 180 degrees F (traditionally standard Chinese green teas brew at a slightly higher temperatures). Pour hot water into the teapot to steep the leaves for only about 1–3 minutes. Larger leaves need more time to steep than finer, smaller leaves. At this point you can also add any fresh herbs you plan on steeping.
On 17 June 2011, at Charles de Gaulle airport in Paris, France, radioactive cesium of 1,038 becquerels per kilogram was measured in tea leaves imported from Shizuoka Prefecture, Japan as a result of the Fukushima Daiichi nuclear disaster on 11 March, which was more than twice the restricted amount in the European Union of 500 becquerels per kilogram. The government of France announced that they rejected the leaves, which totaled 162 kilograms (357 lb).[34]
The Alzheimer's Society commented that "this study adds to previous research that suggests green tea might help to reduce the risk of Alzheimer's disease. However, the researchers used a far higher dose of the active green tea chemical than would ever be found in the human body. More research is needed to see whether green tea is protective at a much lower dose, and to understand the mechanism involved."

Shade grown: All matcha is made from shade-grown tea leaves—a labor-intensive process where tea bushes are protected from the sun and light is filtered to the bushes in a very controlled manor. Shading boosts the chlorophyll production in the plant, giving the leaves a rich green color. The lack of sun reduces the plant’s photosynthesis of the leaves, which in turn alters the naturally occurring levels of caffeine, flavanols, sugars, antioxidants, and theanine. By controlling the sun exposure, tea producers can significantly alter the chemical make-up and flavor of the final tea leaves.