Matcha is made from shade-grown tea leaves that also are used to make gyokuro. The preparation of matcha starts several weeks before harvest and may last up to 20 days, when the tea bushes are covered to prevent direct sunlight.[better source needed] This slows down growth, stimulates an increase in chlorophyll levels, turns the leaves a darker shade of green, and causes the production of amino acids, in particular theanine. Only the finest tea buds are hand-picked. After harvesting, if the leaves are rolled up before drying as in the production of sencha, the result will be gyokuro (jade dew) tea. If the leaves are laid out flat to dry, however, they will crumble somewhat and become known as tencha (碾茶). Then, tencha may be de-veined, de-stemmed, and stone-ground to the fine, bright green, talc-like powder known as matcha.[better source needed]
Although numerous claims have been made for the health benefits of green tea, human clinical research has not provided conclusive evidence of any effects. In 2011, a panel of scientists published a report on the claims for health effects at the request of the European Commission: in general they found that the claims made for green tea were not supported by sufficient scientific evidence. Although green tea may enhance mental alertness due to its caffeine content, there is only weak, inconclusive evidence that regular consumption of green tea affects the risk of cancer or cardiovascular diseases, and there is no evidence that it benefits weight loss.
The leaves are used to make a herbal tea that is called by the names: rooibos, bush tea (especially in Southern Africa), or redbush tea (predominantly in Great Britain). The tea has been popular in Southern Africa for generations, but is now consumed in many countries worldwide. It is sometimes spelled rooibosch in accordance with the original Dutch. The tea has a taste and color somewhat similar to hibiscus tea, or an earthy flavor like yerba mate.
Since some of the bioactive compounds in green tea are anti-viral and anti-bacterial, in much the same way as green tea can kill bacteria in your mouth, it can also inhibit bacteria and viruses in your bloodstream and throughout the rest of your body. Similarly, green tea may inhibit viral and bacterial infection via your nasal passages. All this means that green tea may help prevent colds and the flu, and furthermore seems to be able to alleviate the symptoms of colds and the flu once you are sick.
Matcha typically has more caffeine content than green tea, similar caffeine to black tea, and less caffeine than brewed coffee. Because matcha is produced from shade-grown tea bushes, the tea leaves tend to retain more of their caffeine content. In addition, since you’re consuming the ground tea leaf when sipping matcha, you’re ingesting more caffeine content than you would from the extraction of steeped green or black tea leaves. Like all drinks cultivated from caffeinated plants, however, a specific level of caffeine per cup of matcha tea will depend on the how the matcha was processed and prepared. Be sure and read the packaging carefully or ask your tea supplier directly for the caffeine information specific to the matcha you are buying.