Health effects of drinking tea

Tea drinkers who opt for black, oolong, green or white teas may find that these beverages offer health benefits.

The April issue of Mayo Clinic Health Letter covers what is -- and isn't -- known about the health effects of drinking tea.

Black, oolong, green or white teas have a common origin. Each is produced from the leaves of the Camellia sinensis bush. The leaves are loaded with flavonoids and other polyphenols that work as antioxidants, possibly lowering the risk of some diseases.

While numerous studies have found possible benefits, the actual benefits of drinking tea are not certain. Most research about tea's benefits is based on population (epidemiological) studies. Findings are limited because factors other than tea consumption could influence the results. Here's some of what's known about tea's potential benefits:

Cardiovascular: It's still uncertain if drinking tea over long periods might positively affect cholesterol levels, blood pressure and atherosclerosis. There's some early evidence that regularly drinking green tea may reduce heart attack risk or atherosclerosis. There's conflicting evidence on black tea consumption and heart attack risk reduction.

Cancer: It's still unknown whether regular black tea consumption influences cancer rates. Early lab tests with white tea indicate it may protect against colon cancer in particular. So far, well-designed studies haven't proven this.

Bone and joint health: Early laboratory research indicates green tea could be beneficial in reducing inflammation related to arthritis and slowing cartilage breakdown. Some early data indicate that regular tea consumption might improve bone mineral density in older women.

Memory: Studies are limited, but a recent one found that older adults in Japan who drank green tea daily showed less risk of memory difficulty, compared with those who didn't drink tea regularly.

While there's still much to learn about tea's health benefits, the potential benefits seem to be in the cup, not in supplements or tea extract capsules. So far, there's no certainty that the compounds in supplements are the same ones in tea, and even less certainty that these supplements might provide the same potential health benefits as tea.

Mayo Clinic Health Letter is an eight-page monthly newsletter of reliable, accurate and practical information on today's health and medical news.