Caffeine: Everyone knows that caffeine is an external stimulant and raises blood pressure, and is actually toxic in nature (it may be fatal for some animals). Caffeine is also addictive and can have adverse effects on the liver and internal organs over the course of many years. That being said, it is the component of tea which makes it energizing and refreshing, which is why people are willing to risk it.
Generally, lower-quality green teas are steeped hotter and longer while higher-quality teas are steeped cooler and shorter, but usually multiple times (2-3 typically). Higher-quality teas like gyokuro use more tea leaves and are steeped multiple times for short durations. Steeping too hot or too long results in the release of excessive amounts of tannins, leading to a bitter, astringent brew, regardless of initial quality. The brew’s taste is also affected by the steeping technique; two important ones are to warm the steeping container beforehand to prevent the tea from immediately cooling down, and to leave the tea leaf in the pot and gradually add more hot water during consumption.
There are three main varieties of tea: green, black, and oolong. All three varieties are made from the leaves of the same species of plant called Camellia sinensis; the difference is in how the tea leaves are processed. Green tea is made from unfermented leaves, while oolong tea is made from partially fermented leaves and black tea is fully fermented.
Drinking green tea or taking green tea supplements decreases the blood concentration of total cholesterol (about 3–7 mg/dL), LDL cholesterol (about 2 mg/dL), and does not affect the concentration of HDL cholesterol or triglycerides. A 2013 Cochrane meta-analysis of longer-term randomized controlled trials (>3 months duration) concluded that green tea consumption lowers total and LDL cholesterol concentrations in the blood.
In 1994, Burke International registered the name "Rooibos" with the US Patent and Trademark Office, thus establishing a monopoly on the name in the United States at a time when it was virtually unknown there. When the plant later entered more widespread use, Burke demanded that companies either pay fees for use of the name, or cease its use. In 2005, the American Herbal Products Association and a number of import companies succeeded in defeating the trademark through petitions and lawsuits; after losing one of the cases, Burke surrendered the name to the public domain.