Tea Health Benefits, Risks & Tips

Tea, a shrub in the camellia family, is the world’s most popular nonalcoholic beverage. Most tea is grown in India, Sri Lanka, China, Japan, Taiwan, and Indonesia. 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. 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 flavor as well as many health benefits. The extent to which these compounds are present in the beverage depends on how the leaves are processed.

White tea is made from the green buds and young leaves that are steamed and dried. It is the least processed type of tea. Green tea is made by steaming the leaves to halt any enzyme activity. Black tea is made by crushing, fermenting (exposing the leaves to the air), and drying the leaves. Oolong tea is only partially fermented. The highest concentration of catechins is found in green tea and white 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 flavor.

Herbal teas are not true tea. They are infusions, or tisanes, of various pleasant-tasting plants such as chamomile, fennel, lavender, and peppermint. Because most of them do not contain caffeine, they offer an alternative for people who prefer to avoid this stimulant.

TEA FACT
• Commercial iced teas, flavored with fruit syrups and sweetened with sugar, contain about as many calories as soft drinks.

Health Benefits

Promotes weight loss.
The results from a number of randomized, controlled intervention trials have shown that consumption of green tea catechins (270 mg to 1200 mg a day) may reduce body weight and fat, possibly by increasing energy expenditure and promoting the oxidation of fat.

Helps prevent stroke.
One study found that the risk of stroke was reduced by about 70% in men who drank five or more cups of black tea a day: Other studies showed that the risk of having a heart attack was reduced by more than 40% for men and women who consumed one or more cups of tea per day. Flavonoids in tea 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, unstable molecules that are released when the body consumes oxygen.

Fights diabetes.
Research suggests that people who drink green tea are less likely to develop type 2 diabetes and have a lower risk of death from cardiovascular disease. The biological mechanisms are still unknown but a popular hypothesis is that the epigallocatechin gallate (EGCG) in green tea decreases blood pressure, lowers blood sugar, and increases blood flow.

Fosters heart health.
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.

Inhibits cancer.
A number of studies have shown that tea may offer protection against a variety of cancers. EGCG 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.

Fights infections.
Researchers report in the Proceedings of the National Academy of Sciences that they have found a chemical in tea that boosts the body’s defense against disease fivefold. They say they isolated from ordinary black tea a substance called L-theanine, also found in green and oolong tea. L-theanine is broken down in the liver to ethylamine, a molecule that primes the response of an immune blood cell called the gamma-delta T cell. Gamma-delta T cells in the blood are the first line of defense against many types of bacterial, viral, and parasitic infections.

Alleviates asthma symptoms.
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.

Supports dental health.
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.

Quells diarrhea.
Tea’s binding action makes it useful against diarrhea.

Health Risks

Iron absorption.
The tannins in tea can cut iron absorption by more than 80% when tea is sipped with an iron-rich meal. Tea-drinking vegetarians are especially susceptible. Individuals with a tendency to anemia can drink citrus juice at mealtimes to promote iron absorption; squeezing a wedge of lemon or adding milk to tea also binds the tannins and partly blocks their effect on iron. Tea drinking between meals does not affect iron absorption.

Excessive urination.
Tea has a diuretic effect, which increases the kidneys’ output of urine. Excessive urination can upset the body’s fluid and chemical balance by washing potassium from the body.

Insomnia.
Tea leaves contain twice as much caffeine, weight for weight, as coffee beans do. But when measured by volume, tea has only half as much caffeine as coffee because tea is drunk weaker and coffee is more completely extracted from the grounds. A cup of black or green tea contains 35 to 45 mg of caffeine. Theobromine, which is also found in tea, has effects similar to those of caffeine but milder.

Migraines.
Tea may trigger a migraine headache in hypersensitive people; for others, it may alleviate headaches when taken with aspirin or similar painkillers.

Eating Tips
• Use cooled brewed black tea in place of wine in poultry braises.
• Poach prunes and dried apricots in red rooibos tea.
• Freeze double-strength green tea in cubes, then crush in the food processor to make granita.

 Buying Tips
• For best flavor and healing properties, purchase whole tea leaves.
• Look for unbleached natural fiber tea bags.

Storing Tips
• Store tea leaves in a metal container in a cool spot for up to a year.
• Tea bags retain flavor for about a year.