Cynthia Sass is a nutritionist and registered dietitian with master's degrees in both nutrition science and public health. Frequently seen on national TV, she's Health's contributing nutrition editor, and privately counsels clients in New York, Los Angeles, and long distance. Cynthia is currently the sports nutrition consultant to the New York Rangers NHL team and the New York Yankees MLB team, and is board certified as a specialist in sports dietetics. Cynthia is a three time New York Times best selling author, and her brand new book is Slim Down Now: Shed Pounds and Inches with Real Food, Real Fast. Connect with her on Facebook, Twitter, and Pinterest.

Both nutritionists we spoke to agree that drinking tea when you wake up and before bed can help your system rev up and calm down, depending on which variety you choose. If you’re a tea fanatic, work in a few cups throughout the day: Unless you’re sensitive to caffeine, you can probably handle five to seven cups a day without any negative side effects, says Lagano.

And not all the science has been favorable to tea. A report in the March 1 edition of The New England Journal of Medicine looking at green tea consumption in humans, found no effect on stomach cancers once adjustments were made for other factors that could affect risk. Those other factors included sex, age, history of stomach ulcer, use of tobacco or alcohol, and other dietary habits.
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) 

According to a report published in the Journal of the American College of Nutrition, “Tea is the most consumed drink in the world after water.” (2) What is green tea good for? According to dozens of studies, regularly drinking green tea may reduce your risk of developing heart disease or Alzheimer’s, help you maintain better bone mineral density, ward off eye diseases that affect vision in older age, prevent strokes, and even extend your life.
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)
An animal study published in 2009 in “Phytomedicine” found that green rooibos tea helped regulate glucose metabolism, preventing increases in fasting blood glucose levels during the course of the five-week study. This effect is a result of aspalathin, a compound found in green rooibos. Poor glucose tolerance and high fasting glucose levels are signs of type-2 diabetes and are common in obesity. The study suggests rooibos tea may help keep blood glucose levels in check, preventing sharp spikes and falls that can trigger symptoms of hunger and possibly leading to lower calorie consumption.
^ Jump up to: a b Onakpoya, I; Spencer, E; Heneghan, C; Thompson, M (August 2014). "The effect of green tea on blood pressure and lipid profile: a systematic review and meta-analysis of randomized clinical trials". Nutrition, Metabolism, and Cardiovascular Disease (Systematic Review & Meta-Analysis). 24 (8): 823–36. doi:10.1016/j.numecd.2014.01.016. PMID 24675010.
One of Japan’s own Zen priests studying in China’s Buddhist monasteries returned to Japan in the early 12th century with tea plant seeds and bushes. The young priest, called Eisai, used his experience in China growing and drinking “beaten tea” to popularize what he called “the way of tea” as a meditation ritual within his community of Japanese Buddhist monks. Eventually, he spread the tea drinking custom throughout the rest of Japan.
Tea culture of Korea was actively suppressed by the Japanese during the Japanese forced occupation period (1910‒1945), and the subsequent Korean War (1950‒1953) made it even harder for the Korean tea tradition to survive.[70] The restoration of the Korean way of tea began in the 1970s, around Dasolsa.[70] Commercial production of green tea in South Korea only began in the 1970s,.[71] By 2012 the industry was producing 20% as much tea as Taiwan and 3.5% as much as Japan.[72][73] Green tea is not as popular as coffee or other types of Korean teas in modern South Korea. The annual consumption per capita of green tea in South Korea in 2016 was 0.16 kg (0.35 lb), compared to 3.9 kg (8.6 lb) coffee.[74] Recently however, as the coffee market reached saturation point, South Korean tea production doubled during 2010‒2014,[75] as did tea imports during 2009-2015,[76] despite very high tariff rate (513.6% for green tea, compared to 40% for black tea, 8% for processed/roasted coffee, and 2% for raw coffee beans).
Rooibos tea is anti-inflammatory in nature, which means that it reduces blood pressure and scavenges free radicals like other antioxidants. Quercetin, another powerful antioxidant found in rooibos tea, has been linked to preventing a wide variety of heart conditions. It promotes an increase in HDL cholesterol (good cholesterol) and inhibits the LDL cholesterol (bad cholesterol) from binding to the walls of arteries and blood vessels.
2. Enables digestion: Red tea is caffeine-free and also free of tannins. This element is present in other teas and is known to cause digestive issues among many people. Red tea is a storehouse of antispasmodic elements, preventing diarrhea and gastric issues. It has no oxalic acid, this makes it suitable for those who are prone to developing kidney stones. 

One of the most unexpected health benefits of matcha tea, is that drinkers experience a boost of energy throughout the day. In one study, researchers had thought that this was from the caffeine in matcha, but they found that it was actually the combination of matcha’s natural properties. Another recent study found that matcha even improved physical endurance by 24%.
Green tea leaves are initially processed by soaking in an alcohol solution, which may be further concentrated to various levels; byproducts of the process are also packaged and used. Extracts may be sold in liquid, powder, capsule, or tablet form.[4] Decaffeinated versions are also available.[9] Green tea extract supplements are accessible over the counter in various forms.[10]
There are mixed opinions about how much green tea one should consume. The reality is one cup of green tea isn’t enough to affect your health. Some believe 2 cups of green tea will show benefits while others say 5. Some people say up to 10 cups is ideal but if you’re concerned about spending a lot of time in the bathroom you can add a green tea supplement to your diet.
Studies in laboratory animals have found that green tea polyphenols inhibit the growth of esophageal cancer cells (in line with its anti-cancer properties). Other clinical studies have found that green tea offers protection against the development of esophageal cancer, particularly among women. However, one large-scale population-based clinical study found just the opposite: drinking green tea was associated with an increased risk of esophageal cancer, and the stronger and hotter the tea, the greater the risk. It seems that if the water is very hot, it can damage the esophagus and lead to long-term adverse consequences. So just make sure the tea you drink isn’t extremely hot.
In 1904, Benjamin Ginsberg ran a variety of experiments at Rondegat Farm, finally curing rooibos. He simulated the traditional Chinese method of making Keemun by fermenting the tea in barrels. The major hurdle in growing rooibos commercially was that farmers could not germinate the rooibos seeds. The seeds were hard to find and impossible to germinate commercially.[citation needed]
Other Risks: Long-term consumption, in excessive quantities, may give rise to problems such as insomnia, restlessness, annoyance, irritability, headaches, hypertension, abnormal heartbeat, loss of appetite, spasms, constipation, and acute addiction to caffeine. Many times, people who are addicted to caffeine do not feel normal without the substance and suffer from acute constipation, irritation, and lack of concentration in the absence of green tea.

On this episode of Consumed, host and Eater Drinks editor Kat Odell looks into the matcha production process — how it differs from that of more traditional steeped green tea, and how two of New York's noted matcha purveyors (Ippodo Tea Company and Matchabar) are working with the product today. Watch the video above for a lesson in powdered green tea; if your interest is piqued, check this map for the best places to drink matcha across the country, and these recipes for making iced matcha drinks at home, perfect for the summer.
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