Health benefits of tea match those of coffee

The Medicine Cabinet: Ask the Harvard Experts

Q: I keep hearing about the health benefits of drinking coffee. I am tea drinker and really enjoy it. But would it be better for my health if I switch?

A: You’re correct. Over the last few years, there has been a flurry of studies showing the positive health effects of coffee consumption. While tea has taken a back seat of late, tea drinkers should continue to enjoy their beverage of choice. Here’s why.

Tea contains substances that have been linked to a lower risk for heart disease, stroke, diabetes and certain cancers. Also drinking tea can help improve mood, concentration and mental performance.

Those health enhancing substances are chemicals called polyphenols, in particular catechins and epicatechins. They get enriched in tea, especially green tea.

The fermentation process used to make green tea boosts levels of polyphenols. Black and red teas have them, too, but in lesser amounts and types that are less strongly tied to improved health.

Polyphenols act as antioxidants. Antioxidants latch on to and neutralize chemicals called oxidants, which cells make as they go about their normal business. Elevated levels of oxidants can cause harm to many tissues. For example, they damage artery walls, increasing heart disease and stroke risk.

While regular tea drinkers appear to have better health, that doesn’t prove that the tea itself is the reason. Studies attempt to rule out the possibility that tea drinkers simply live healthier lifestyles, but it’s difficult to be sure.

Like so many things in life, moderation is the key. For instance, drinking tea can help prevent kidney stones. But for people who have already had a kidney stone, the high oxalate content in some teas increases the chance of another stone forming. And of course, too much caffeinated tea can cause the jitters and keep you up at night.

Although green tea has a high concentration of polyphenols, it does have a slightly bitter edge. It’s tempting to use a sweetener. But don’t overdo it. The extra sugar will neutralize any of the potential health benefits from the tea.

(Howard LeWine, M.D., is an internist at Brigham and Women’s Hospital in Boston and assistant professor at Harvard Medical School. For additional consumer health information, please visit www.health.harvard.edu.)