Sales of tea are soaring, with green teas, black teas, chais and herbals all hot options.

But determining which teas to drink – and which ones are low in caffeine, high in antioxidants and still flavorful – is about as difficult as, well, reading tea leaves.

Is green tea truly better for you than other teas? Does it contain caffeine? How about yerba mate, the hot drink of celebrities? What about black and red teas? And what is oolong tea, anyway?

"It's so easy to get confused about tea," said Beverly Hernandez, a registered dietitian at Piedmont Hospital in Atlanta. "Americans are converting from coffee to tea because it contains half the caffeine, and that's good, but people often aren't aware of how much caffeine various teas contain."

Here's the rundown:

Not fermented and, therefore, generally contains more antioxidants than other teas. Less caffeine than black tea. Health claim: Vitamin C helps immune system and promotes good health. Contains fluoride that helps strengthen bones and prevents cavities.

Not as processed as black tea but more so than green tea. Has a richer flavor than green tea but more delicate than black. Health claim: Helps with indigestion and lowers cholesterol, boosts metabolism.

High-quality black tea (fully fermented, containing more caffeine than other teas but still only half as much as coffee). Health claim: Lowers risk of stroke. High concentration of flavonoids helps reduce clotting and acts as an antioxidant.

Natural source of antioxidants with high level of flavonoids. Caffeine-free. Health claim: Helps soothe upset stomach and diminishes hay fever symptoms. Reduces insomnia, irritability, headaches, nervous tension and hypertension.

Not derived from the tea plant, but from an herb that was believed for years to contain no caffeine. Scientists recently discovered, however, that mate does have caffeine. Health claim: Energizes body, boosts immunity, tones nervous system, eliminates insomnia, aids weight loss, is a gentle diuretic and more.