Updated December 10, 2018.
There’s a reason everyone from your grandmother to your health care provider recommends a cup of tea to remedy a variety of ailments. After all, tea has been shown to relieve stress, enhance immune function, soothe a sore throat, and more. And recent research indicates that tea may be helpful for protecting against even more ills, from eczema to secondhand smoke.
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What makes tea so healthy?
Most teas are derived from the Camellia sinensis plant (with the exception of herbal tea, which can be made from a variety of herbs, spices, and other plant material, and usually doesn’t contain caffeine). True teas all share similar health benefits, thanks to unique antioxidants called flavonoids, the most potent of which is ECGC, a potential protector against free radicals that contribute to cancer, heart disease, and clogged arteries. Green, black, white, and oolong teas also all contain varying levels of caffeine and theanine, an amino acid that may heighten mental alertness. Finally, these teas contain natural compounds known as polyphenols—also found in fruit, vegetables, cereals, and beverages—which may reduce the risk of a variety of illnesses, including cancer and heart disease.
Here’s a look at five popular teas and some of the health benefits associated with them.
Exposing tea leaves to oxygen-rich, moist air darkens their natural green hue, a process called oxidation. Oxidization is responsible for the dark color of black tea as well as the formation of two compounds, theaflavins and thearubigins, which influence black tea’s signature taste and may contribute to its health benefits.
Why it’s good for you: An animal study published in the Journal of Inflammation suggests black tea may protect lungs exposed to cigarette smoke by preventing oxidative damage and apoptosis (programmed cell death). And according to a review published in the European Journal of Clinical Nutrition, there is also sufficient evidence to suggest that black tea may reduce the risk for coronary heart disease due to its high concentration of polyphenols.
How much helps: The researchers behind the animal study didn’t make a specific recommendation regarding how much black tea might be beneficial for humans, but their results indicate that “regular intake” may protect smokers’ lungs. According to the research on coronary heart disease, daily consumption of 3 or more cups is associated with a reduced risk. Because black tea is high in caffeine, limit your intake to no more than 5 cups a day in order to avoid potential side effects such as difficulty sleeping, headaches, and irritability. Experts recommend no more than 400 milligrams of caffeine daily.
Oolong teas are oxidized less than black teas but more than green teas. The leaves are withered in direct sunlight before being shaken in bamboo baskets and air-dried several times, and then pan-fired at high temperatures to prevent further oxidation. This limits the amount of moisture in the teas and prolongs the shelf life.
Why it’s good for you: One Japanese study found that oolong tea could be beneficial for people suffering from a specific form of eczema, and another study suggests antioxidants in oolong may help lower high levels of LDL (or “bad”) cholesterol. A small Taiwanese study found that after consuming about 6 cups of Chinese oolong tea each day for 30 days, participants had significantly lower blood sugar levels.
How much helps: The participants in the eczema study drank approximately 1.5 cups of oolong tea 3 times per day, but the participants in the blood sugar study drank up to 6. An 8-ounce cup contains around 50 to 75 milligrams of caffeine.
Made from un-oxidized leaves, green tea is one of the less processed types of tea and therefore contains a higher concentration of antioxidants and polyphenols. Traditionally used in traditional Indian and Chinese medicine, green tea has been the focus of numerous research studies investigating its health benefits.
Why it’s good for you: One small study using functional magnetic resonance imaging (MRI) found that green tea may improve cognitive function, and other research indicates it may also reduce the risk of neurological disorders like Alzheimer’s and Parkinson’s diseases.
How much helps: Researchers generally recommend 2 to 3 cups of green tea per day for a beneficial dosage of polyphenols. One 8-ounce serving typically contains between 24 to 45 milligrams of caffeine, but caffeine-free green tea products are also available.
Also made from the Camellia senensis plant, white tea is made when the leaves are steamed or fried, and then dried almost immediately after harvesting. Because of the minimal processing involved, white tea retains a higher concentration of catechins, the antioxidants that fight and may prevent cell damage, and may help prevent atherosclerosis, hypertension, and other heart diseases.
Why it’s good for you: One study suggests that white tea may contain the most potent anti-cancer properties of all tea varieties, due to a higher concentration of polyphenols. Another study indicates compounds in white tea may prevent the breakdown of elastin and collagen in the skin, which can lead to wrinkles that accompany aging.
How much helps: It’s not known how much white tea was needed to see the benefit in either of the studies mentioned above. But one 8-ounce serving of white tea typically contains only between 30 and 55 milligrams of caffeine, so several cups a day is generally considered safe for healthy individuals.
Herbal tea isn’t made from the leaves of the Camellia sinensis plant, and the chemical constitution varies depending on the plants used. Because it may be made from a variety of fruits, seeds, herbs, and roots, it may have a lower concentration of antioxidants compared to other teas. Common varieties include jasmine, mint, chamomile, and ginger teas.
Why it’s good for you: There is limited research on the health benefits of herbal teas, but research indicates antioxidants in chamomile may help prevent complications from diabetes, and one small study found that 3 cups of hibiscus tea a day lowered blood pressure in people with elevated levels. Ginger tea appears to be helpful for digestion, and peppermint tea is soothing to the lower gastrointestinal tract, but it can cause heartburn in some people.
How much helps: Because of the variability, there is no recommendation for herbal tea dosage, and further research is necessary to demonstrate additional health benefits.
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