Air Date: Week of April 25, 2003

Living on Earth’s Jessica Penney reports on how drinking tea may improve your immune system.

Transcript

CURWOOD: Coming up, too much of a good thing: how abundant irrigation may end up putting some farmers out of business in California. First this environmental health note from Jessica Penney.

[MUSIC: Health Note Theme]

PENNEY: For centuries, people have believed that drinking tea can be good for you. Recent studies have focused on the beneficial antioxidants in tea, but now scientists in Boston have discovered a new way that tea may improve your health, by bolstering the immune system.

The researchers had one group of people drink five cups of tea a day for a month. Another group drank five cups of coffee. The scientists took blood samples from both groups and isolated immune cells to test how they responded to infections. They added molecules associated with certain bacteria and tumor cells to the immune cell samples. Over 60 percent of the tea drinkers had immune cells that responded quickly by dividing and producing bacteria-killing chemicals. Only 10 percent of the coffee drinkers showed this response.

The researchers think this happens because black and green teas, but not coffee, contain small molecules that are similar to molecules produced by the bacteria and tumor cells. The tea compounds are harmless, but the similarity helps prime human immune cells to recognize harmful bacteria and be ready to fight infection. This is basically the way a vaccine works.

In a separate test, the tea drinkers’ cells even responded to a different kind of bacteria that doesn't produce molecules similar to those in teas, indicating that tea might boost the immune system in a variety of ways. The scientists plan to repeat these tests with more volunteers.

That's this week's health note. I'm Jessica Penney.

CURWOOD: And you're listening to Living on Earth.