Tea is hot: Americans downed more than 3 billion gallons of it in 2010. Worldwide, tea is the most widely consumed beverage after water. And a daily cup or two confers surprising health benefits, research shows.
"There's been a lot of research about tea's beneficial compounds," says integrative nutritionist Beth Reardon of Duke University. "For example, it's one of the richest sources of antioxidants you can consume."
Here are five tea benefits worth lifting your teacup to:
How Tea Can Help You Lose Weight
How it works: Compounds in the Camellia sinensis plant (from which comes all black, green, and white tea) provide a mild metabolic boost that amounts to the body burning an extra 45 to 50 calories a day, Reardon says. "It sounds small, but over just a year, that could easily add up to five or more pounds."
What's more, in 2011 Japanese researchers identified two tea compounds, theaflavins and thearubigins, that slow weight gain in rats fed a high-fat diet -- though only when there was no milk added (proteins in cow's milk interfered with weight control). Chinese researchers have identified another compound in tea called catechins, which also contribute to weight loss.
Here's one other way drinking tea contributes to weight loss: Without additives like dairy or sugar, tea is a zero-calorie substitute for sodas, juice, or sugared drinks. And the more tea you sip, the fuller you feel.
Tea note: Neither herbal teas -- which are made from infusions of fruits, leaves, roots, grains, and flavorings -- or green tea capsules have been shown to contribute to weight loss.
How Tea Can Keep You Calm and Focused
How it works: The caffeine in black and green teas can contribute to keeping you awake, although not as well as coffee. But another compound called L-theanine, a unique neurologically active amino acid that crosses the blood-brain barrier, can also have a direct effect on your ability to focus. By altering brain-wave activity, the substance has been shown to create a relaxed, alert state.
Green tea is an especially good source of L-theanine. Three to four cups of tea a day have been shown to have a calming effect while also enhancing attention, Reardon says. It's like having the jolt of joe but without the jittery side effect.
Regular tea drinkers have also been found to have lower levels of cortisol -- the "stress hormone."
Tea note: Worried that tea will dehydrate you? To the contrary: Researchers have found tea to be as hydrating as water -- and possibly even more beneficial, since it provides protective antioxidants while also replacing fluids. (Coffee tends to be more dehydrating, since it contains almost twice as much caffeine as even strongly brewed tea.)
How Tea Can Help Repair Cancerous Cell Damage
How it works: Tea is one of the richest sources of flavonoids, an antioxidant plant compound that can help fight cell damage. Flavonoids help regulate the normal cell cycle or reestablish a cell cycle gone awry. That means that flavonoids help repair DNA damage that can make cells become cancerous, or repair signals that encourage abnormal cells to self-destruct before they reproduce rampantly. "Flavonoids can act to put out the fires of oxidative damage," Reardon says.
Green tea has been linked in research studies to a reduced risk of breast cancer, skin cancer, lung cancer, colon cancer, ovarian cancer, and bladder cancer. Black tea has shown similar benefits in various cancer studies, but it contains lower concentrations of antioxidants. (Green tea has been the most studied in terms of cancer prevention and is a hotbed of ongoing research.)
Tea note: Let green tea steep for several minutes in order to get the maximum flavonoids. Green tea is the best food source of catechins, an antioxidant that may be more powerful than vitamin C and vitamin E in its ability to halt oxidative damage. Tea also has higher concentrations of polyphenols (a type of antioxidant that's even better at combating the free radicals that cause cell damage) than most fruit or vegetable sources.
How Tea May Ward Off Postmenopausal Bone Loss
How it works: Scientists aren't sure exactly how tea seems to protect the microarchitecture of bones. But there's growing evidence that women ages 65 to 76 who drink black tea have stronger bones than their counterparts who don't. In both women and men over age 50, drinking black tea has been associated with a lower risk of hip fracture in some studies. Other studies have found that those who drink the highest levels of green tea tend to have the lowest rate of osteoporosis.
The research about bone health and tea is still considered speculative, but some health experts recommend drinking tea as a preventive measure for those who are premenopausal or who are at risk of osteopenia (bone thinning that's a precursor to osteoporosis).
Tea tip: You can vary the taste of tea by experimenting with different types: black, oolong, green, and white. Black has the most caffeine, while white has the most antioxidants (followed closely by green) and the least caffeine. The difference between the four types lies in their processing: White tea is picked and air-dried. Green tea is picked, heated (usually steamed), and then dried. Black tea goes through an added step of oxidation, and oolong is partly oxidized.
How Tea Protects Your Teeth and Gums
How it works: The antioxidant catechin found in tea may help reduce inflammation and inhibit the growth of harmful plaque, protecting teeth and gums. Tea also contains some fluoride -- the enamel-protecting substance that dentists recommend.
A 2009 study in the Journal of Periodontology looked at 940 Japanese men ages 49 to 59 and found that those who drank green tea regularly had healthier gums than those who drank less green tea. For every cup of green tea consumed per day, there was a decrease in three key indicators of periodontal problems. (Periodontal disease is a chronic inflammatory disease of the gums and bones.)
Other studies at the University of Illinois College of Dentistry have found similar benefits from black tea and oolong tea. These teas can affect the enzyme responsible for converting sugars into the sticky material that plaque uses to adhere to teeth. Black tea also destroys or suppresses growth and acid production of cavity-causing bacteria.
The same UI team found that rinsing with black tea for 30 seconds every three minutes, five times in a row, stops oral bacteria from growing and producing the acid that causes cavities.
Tea note: You can drink tea hot or cold, although be aware that iced tea tends to be more diluted. Some 85 percent of the tea drunk in the United States is iced tea, usually made with black tea, according to the Tea Association of the U.S. Be aware, too, of one potential downside for your pearly whites from black tea (whether cold or hot): It tends to stain enamel.