Quiz: The Truth About Tea

Tea leaves come from the Camellia sinensisplant. They contain antioxidants that counter free radicals, which can damage cells. Antioxidants may reduce or help prevent some of this damage.

The difference between the three main varieties of tea (green, black, and oolong) is the process used to make them. Black tea is exposed to air, or fermented, which darkens the leaves and gives them flavor. Green tea is made by heating or quickly steaming the leaves. Oolong tea leaves are partially fermented.

There’s no hard evidence that drinking tea can prevent cancer in people in general; many factors affect cancer risk. However, several studies have linked drinking tea to a lower risk of cancer for some people. More research is needed to define those groups.

Some studies show that drinking green tea may help curb a few heart disease risk factors, including body weight, blood pressure, and cholesterol absorption. However, the FDA denied a petition filed by a green tea maker that wanted to put heart-health claims on its product's label, ruling that there wasn’t credible scientific evidence to support the claims.

There is some evidence that green tea may help control glucose (or blood sugar) levels; however, that hasn't been widely tested in people. More research is needed to learn how much green tea would be needed and whether green tea also helps curb body weight and body fat.

Herbal teas are not made from the Camellia sinensisplant and are not really teas at all. Herbal teas are infusions of leaves, roots, bark, seeds, or flowers from other types of plants. Common herbal teas include chamomile and mint. They are not associated with the potential health benefits of green, black, or oolong tea.

You get the most antioxidants from freshly brewed tea; those compounds are reduced in instant tea, decaffeinated tea, and bottled tea. Researchers have not determined how many cups of freshly brewed green tea are recommended each day, but people in Asia typically drink at least three cups daily.

Fresh brewing is the way to get the most antioxidants from your tea, so knowing how long to steep the tea is an important part of the process. Three to five minutes is the recommended amount of time for maximizing the benefits.

Iced tea often contains low to negligible amounts of catechins compared with the high concentrations found in a cup of hot tea, because adding water to brewed tea dilutes the concentration. However, iced tea and hot tea could contain approximately the same level of antioxidants if, when preparing iced tea, you use 50% more tea than when preparing a similar amount of hot tea, to allow for dilution. About 85% of the tea drunk in the U.S. is iced tea.

Blended teas are made with teas of different origins, combined to achieve a certain flavor. For example, English breakfast tea traditionally was a blend of China Keemum teas, but the blend now includes Ceylon and India teas as well.

Little is known about the effects of green tea on children, because the research on green tea has been done on adults.

Green tea contains caffeine, so pregnant women or those who are breastfeeding shouldn’t drink more than one or two servings of green tea per day, according to the Academy of Nutrition and Dietetics. People with irregular heartbeats or anxiety disorders also should be cautious about how much caffeine they get, from green tea or other sources.

A Swiss study found that drinking black tea with a meal reduced iron absorption by 79% to 94% when compared with drinking water. People with an iron deficiency might consider drinking tea only between meals.