Does Tea Hydrate You As Much As Water? Here's What The Science Says

Tea is the world's most popular drink after water. For most adults, consuming between two and four cups of tea per day is considered highly beneficial. Not only is it calorie-free, it's also packed with polyphenols (antioxidants) and supports hearth health. What's more, a cup of tea can do wonders for calming your nerves due to the presence of an amino acid called L-theanine (check the best teas for soothing anxiety). But the real question is whether it works as effectively as plain water at keeping us hydrated.

Dr. Carrie Ruxton, a dietitian at the Tea Advisory Panel, an independent group of U.K.-based nutritionists, dietitians, and doctors, explained in an exclusive talk that tea is just as hydrating as plain water. "We conducted a randomized controlled trial where tea was compared with water; either at four or six servings daily," she told Chowhound. The 2011 paper, published in the British Journal of Nutrition (via Cambridge University Press), found no difference in blood or urine markers between tea and water consumers.

Although the study was limited to participants at rest in a controlled lab setting, Dr. Ruxton reported that earlier research from the European Journal of Applied Physiology (via Springer Nature Link) shows that tea can also support hydration under more physically stressful conditions. "For example, there was a study at [Mount] Everest base camp which looked at climbers consuming tea versus other non-caffeinated drinks," she highlighted. "Again, there were no differences in urine markers of hydration but, interestingly, the group drinking tea reported significantly less fatigue."

However, tea does come with a catch: caffeine, one of the most common stimulants in the world. It is naturally present in all teas which derive from the Camellia sinensis plant, including black, green, white, and oolong. While herbal tea is caffeine free, black tea has the highest caffeine content (over 50 milligrams per cup). Discussing how black tea's caffeine content compares to coffee, Dr. Carrie Ruxton stressed herbal teas may be slightly better for keeping fluid levels up. "Coffee has double the caffeine of a cup of tea, on average (80-120 milligrams per serving depending on the type), and would be less hydrating," she explained. "Sodas are hydrating, but their high sugar content makes them far less healthy than teas."

Caffeine is a mild diuretic, which means consuming more than 500 milligrams a day (more than five cups of caffeinated beverages), can lead to dehydration. "Caffeine can influence hydration when a large amount is consumed at once ... or when people are not used to taking caffeine," Dr. Ruxton said. "This is why caffeinated drinks are not recommended for young children." She also stated that tea contains no additives, since its nutrients and other compounds come naturally from the tea plant. However, some mass-market tea brands do use artificial flavors and colors to mask the use of lower-quality tea leaves. Even so, she confirmed tea can be a good, healthy way to support people's daily fluid intake requirements.