Caffeine content: Matcha tea contains some amount of caffeine which may trigger allergic reactions. These reactions may include diarrhea, cardiac arrhythmia, and irritable bowel syndrome. Caffeine can also cause drug interactions basis the amount consumed. If you are new to matcha and are unaware of its sensitivities, then it is always advisable to ensure natural vigilance while trying it for the first time.
In 2004, scientists at the University of Newcastle studied the effects of black and green tea on Alzheimer’s disease. In laboratory studies, both teas prevented the breakdown of acetylcholine, the neurotransmitter strongly linked with memory. The teas also inhibited enzymes known as BuChE and beta-secretase. These enzymes are found in protein deposits found in the brain of Alzheimer’s patients. (7)
Houjicha: Also spelled as “Hojicha”, this is not a pure or absolute green tea. Rather, it is a mixture of green tea and powdered roasted cereals such as wheat, barley, or rice. The quality and price of this variety depend upon the percentage or ratio of green tea to cereal content. The better ones, which have more green tea in them, are more expensive and have a greener look when brewed; on the other hand, those with higher grain contents yield a golden brown color and are cheaper.
Experts emphasize that the primary thrust of scientific research has been on the pure tea products -- green, black, or oolong tea, derived from a plant called Camellia sinensis. All of the many other "herbal" or "medicinal" teas found in supermarkets and health food stores may be tasty, and may be good, bad, or indifferent for your health -- but they haven't been the focus of concentrated research, says John Weisburger, PhD, of the American Health Foundation.

Along with caffeine, which gives green tea its characteristic taste, bitterness, and stimulating effect, green tea is also rich in a group of chemicals, called catechin polyphenols (commonly known as tannins, which contribute to bitter taste and astringency). These catechin polyphenols include catechin, epicatechin, epicatechin gallate (ECG), epigallocatechin gallate (EGCG), and various proanthocyanidins. They are also known as flavonoids and are very powerful antioxidants. Flavonoids, together with some amino acids like thiamine, are responsible for the potent flavor of green tea. 

It’s important to note that I was not interested in, hoping for, or expecting any drastic changes to my appearance. I already lead a pretty healthy lifestyle: I drink 80 oz. of water a day, I work out at least 4-5 days a week, and I do my best to eat lean protein and lots of fruits and veggies. Like I said, I love food, but I’m usually good at keeping my cravings in moderation. I did not have a “goal weight,” and there were no numbers I was hoping to change (blood pressure, weight, heart rate, etc.). I cannot stress this enough: Acknowledge your own body, its needs, and its goals before you try any new regimen. A detox should fit into your life — you should not expect it to change your body overnight.

"Drink tea if you enjoy it, in moderation, and not because you're taking it as a medicine," says Dr. Sesso. Stirring in a little sugar is fine, but if you add a few heaping teaspoons of sugar, you're probably canceling out tea's possible benefits, he notes. And beware of the sugar found in many bottled teas, some of which contain as much as nine teaspoons of sugar per serving—almost as much as colas and other soft drinks. Check bottled tea labels and choose only pure, unadulterated tea—or save money and brew your own at home.
Grown under shade for three weeks prior to plucking, gyokuro is one of the most exclusive varieties of tea produced in Japan.[60] The shading technique imparts a sweeter flavor, and produces a particularly rich color thanks to the higher amounts of chlorophyll in the shaded leaf. Gyokuro tea is associated with the Uji region, the first tea-growing region in Japan. It is often made using smaller-leaf cultivars of the tea plant.[61]