Studies on green tea’s impact on cancer have been mixed. But green tea is known to aid healthy cells in all stages of growth. There are some clues that green tea may help destroy cancer cells, but that research is still in its early stages, so you shouldn’t count on green tea to prevent cancer. In fact, the National Cancer Institute's web site says it "does not recommend for or against the use of tea to reduce the risk of any type of cancer." 

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.
So what are the best detox teas to choose? If you’re really focused on a start-and-stop teatox (rather than just incorporating detox teas into your diet), check out programs like SkinnyMe Tea, which offers 14- or 28-day packages of high-quality, loose-leaf herbs to steep. Or save a little cash and try one of these four off-the-shelf detoxifying varieties, recommended by Lagano and Villacorta. 

Researchers from the Netherlands confirmed in a recent study that two green tea compounds, L-theanine and caffeine, can significantly boost levels of attention and alertness, building on what is already known about the brain benefits of green tea. The drink is less likely to make you jittery and anxious than other energy-boosting drinks, because it contains lower levels of caffeine than other teas or coffee. In another study published in the American Journal of Clinical Nutrition, researchers discovered that drinking just one cup of green tea a day made people age 55 and older 38 percent less likely to experience a decline in their mental abilities. Drinking a second cup daily made them 54 percent less likely to show mental declines.
Like black and green tea, rooibos is rich in polyphenols, such as rutin and quercetin. Cell and animal studies, mostly from South Africa, have shown that rooibos extracts have antioxidant, immune-stimulating, and anti-cancer properties. But studies of rooibos tea in people are limited. There’s little or no evidence to back claims that it relieves constipation, headaches, eczema, asthma, insomnia, high blood pressure, mild depression, ulcers, diabetes, and so on.
This best-selling detox tea has a loyal following, with thousands of reviewers claiming that it helped with excess bloating, daily digestive issues, and ultimately contributed to weight loss when consumed alongside a balanced diet and regular exercise. Made with green tea leaf, matcha green tea, and guarana seed, this tea blend is quite caffeinated — so don't sip it before bedtime. 

Green Tea comes from Camellia sinensis leaves that are immediately steamed or pan-fired rather than being exposed to air so that no oxidation occurs.   This special handling makes for a more delicate brew that is typically lower in caffeine than black and Oolong teas.  Although amounts vary, green teas are highest in polyphenols known as EGCG, which is why so many make it part of their healthy lifestyle.
Rooibos contains polyphenols that have anti-inflammatory, antiviral, and antimutagenic qualities. Polyphenols are organic chemicals that are often praised for their antioxidant capabilities. Studies suggest that regularly drinking organic red rooibos tea provides the liver with potent antioxidants, helping the organ to improve detoxification. Antioxidants act as scavengers of free radicals throughout the body, which are detrimental byproducts of cell metabolism that can cause cancer and heart diseases. Aspalathin and nothofagin are two other vital antioxidants that rooibos tea contains, making it a great beverage to boost your immune system and protect your body against all types of diseases.
Because you’re consuming whole leaves in matcha, you may get three times as much caffeine than a cup of steeped tea, about the amount in a cup of brewed coffee. Matcha aficionados say that compared to the caffeine buzz from coffee, matcha creates an “alert calm” due to a natural substance it contains called l-theanine, which induces relaxation without drowsiness. Still, I do believe it’s best to nix all forms of caffeine (including matcha) at least six hours before bedtime, to ensure a good night’s sleep.
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]
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