All About Tea
Tea is the world’s most popular nonalcoholic beverage. Most tea is grown in India, Sri Lanka, China, Japan, Taiwan, and Indonesia from a shrub in the camellia family. Like coffees, the best-quality teas are grown in the shade at high altitudes, and the finest leaves are plucked from the youngest shoots and unopened leaf buds, which also contain the highest levels of phenols, enzymes, and caffeine. Researchers are discovering evidence that tea may offer not only soothing warmth and mild stimulation, but also health benefits.
An Antioxidant Brew
Tea contains hundreds of compounds, including various flavonoids, a class of chemical with powerful antioxidant properties. A subclass of flavonoids, the catechins, is responsible for the flavour as well as many of the beneficial health effects of tea.
The extent to which these compounds are present in the final beverage depends on how the leaves are processed. To make black tea, the dried leaves are crushed to liberate enzymes, which react with the catechins over a few hours to produce changes in colour and flavour. This is often referred to as “fermentation.” Green tea is not fermented, it is made by first steaming the leaves to halt any enzyme activity. Oolong tea is partially fermented. The highest concentration of catechins is found in green tea, although black tea is also a good source. Brand-name teas are mixtures of as many as 20 different varieties of leaves, blended to ensure a consistent flavour.
A cup of hot brewed tea has only 2 calories and-with one exception in green tea-no appreciable vitamins or minerals, except for fluoride. Green tea contains vitamin K, a nutrient needed for normal blood clotting.
Drink to a Healthy Heart
The antioxidants in tea may explain the fact that people who drink a lot of tea are much less likely to die from heart disease. Antioxidants prevent the oxidation of cholesterol, making it less likely to stick to artery walls.
One study found that the risk of stroke was reduced by about 70 per cent in men who drank five or more cups of black tea a day, and other studies showed that the risk of having a heart attack was reduced by more than 40 per cent for men and women who consumed one or more cups of tea per day. Flavonoids may protect against stroke in two ways. They reduce the ability of blood platelets to form clots, the cause of most strokes. They also block some of the damage caused to arteries by free radicals, the unstable molecules that are released when the body consumes oxygen.
Cure for Cancer?
A number of studies have shown that tea offers protection against a variety of cancers. A type of catechin called EGCG (epigallocatechin gallate) is thought to be responsible for tea’s anticancer properties. EGCG protects the DNA in cells from cancer-causing changes. It may also inhibit an enzyme that cancer cells need in order to replicate.
The flavonoids in tea may suppress the growth of harmful bacteria, which helps prevent infections.
Tannins, which are found in wine as well as tea, are chemicals that bind surface proteins in the mouth, producing a tightening sensation together with giving the impression of a full-bodied liquid. They also bind and incapacitate plaque-forming bacteria in the mouth. The fluoride in tea-particularly green tea-also protects against tooth decay. Tea’s binding action makes it useful against diarrhea.
Bottoms Up to Breathe Easier
Naturally occurring theophyllines in tea dilate the airways in the lungs and have been found to help some people with asthma and other respiratory disorders to breathe more freely. In fact, theophyllines have been developed as drugs to treat asthma and other constrictive lung disorders.