Tea drinkers are less likely to develop cardiovascular disease than those who don't drink this soothing beverage. The hefty dose of flavonoids in tea may keep the heart and blood vessels healthy, according to the July 2015 Harvard Heart Letter.

"Tea is a good source of compounds known as catechins and epicatechins, which are thought to be responsible for tea's beneficial health effects," says Dr. Howard Sesso, associate professor of medicine at Harvard Medical School and associate epidemiologist at Brigham and Women's Hospital. These compounds belong to the flavonoid family of plant chemicals.

Flavonoids have been shown to quell inflammation. That, in turn, may reduce the buildup of cholesterol-filled plaque inside arteries. Green tea has slightly higher amounts of flavonoids than black tea. Short-term studies have shown that drinking tea may improve vascular reactivity—a measure of how well blood vessels respond to physical or emotional stress. There's also evidence that drinking black or green tea may lower harmful LDL cholesterol levels.

Several large, population-based studies show that people who regularly drink black or green tea may be less likely to have heart attacks and strokes. However, people who drink tea tend to be different from people who don't drink tea. As a result, researchers can't be certain if it's the tea or something else that tea drinkers do that lowers their risk of cardiovascular disease.

"Drink tea if you enjoy it, in moderation, and not because you're taking it as a medicine," says Dr. Sesso. Stirring in a little sugar is fine, but adding a few heaping teaspoons of sugar probably cancels out tea's possible benefits, he notes. And beware of the sugar found in many bottled teas, which can contain up to nine teaspoons of sugar per serving—almost as much as colas and other soft drinks.