After water, tea is the most commonly consumed beverage in the world. But can it really improve your health, as claimed?
Black, green, oolong and white tea all come from the Camellia sinensis shrub and contain a range of polyphenols, notably flavonoids, which have antioxidant and other biological properties that are thought to help protect against disease. Green teas, for example, are rich in catechins, while black tea contains thearubigens and theaflavins. Various polyphenols may have different biological properties and thus different effects in the body—and so far, no one knows if any type of tea is “best.”
Here’s a brief look at some of the research:
Heart health: Population studies have linked tea consumption with a reduced risk of cardiovascular disease. Tea may lower LDL (“bad”) cholesterol and make it less susceptible to artery-damaging oxidation, as well as improve blood vessel functioning, lessen inflammation and inhibit blood clotting. But not all studies show heart benefits.
Cancer: In lab studies, tea polyphenols have been shown to inhibit various cancers, including colon, bladder, lung, skin and prostate. Results from human studies, however, are less consistent. Several observational studies in women, for example, have linked tea with reduced risk of ovarian cancer. On the other hand, one review article cited mixed results on tea and lung cancer.
Body weight: There’s some evidence that tea may have a weight-loss effect, though not all studies find this, and any benefit would be modest at best. In a small study a few years ago, oolong and green tea boosted energy expenditure in healthy women. And in a Swiss review, most studies found that green tea reduced body weight and body fat. Tea polyphenols may stimulate energy metabolism and boost fat burning, but part of the effect may also be due to tea’s caffeine.
Bone health: Long-term tea drinkers tend to have greater bone density than nondrinkers, several studies have found. Tea contains fluoride, flavonoids and other compounds that are good for bones.
The brain: Lab studies support the role of tea in aiding cognition. Studies in people, however, are limited. In a Japanese study in 2006, older people who reported drinking as little as four to six cups of green tea a week had a reduced risk of cognitive impairment compared to those who drank less.
Bottom line: Though its effects in the body are not fully understood, tea can be a healthy addition to your diet. And all types have something to offer. Without added sugars or milk, tea has negligible calories. But check the labels on bottled and instant teas, since many have lots of added sugar. If you don’t like caffeine, decaffeinated tea is often available.