Here's everything to know about the caffeine content of green tea.
Americans love a good beverage—especially if it’s caffeinated. Coffee holds the top spot for the nation’s favorite source of caffeine, with an estimated 62 percent of Americans drinking coffee daily, according to 2020 data from the National Coffee Association. But let’s not forget about tea, especially green tea, another caffeinated beverage that also boasts some health benefits.
Types of Tea
Under the umbrella of tea, there’s an entire world of different varieties. You can find (typically non-caffeinated) herbal teas like peppermint, chamomile, and ginger. Then there are teas that come from the Camellia sinensis plant: black teas, white teas, green teas, and other varieties. Of them, green tea gets a lot of credit for being high in antioxidants and giving the brain a potential boost in cognition.
Since the caffeine content in all of these different types of tea can vary—and some contain no caffeine at all—many people wonder whether green tea is caffeinated. In short, yes it is.
We asked registered dietitians to explain the caffeine content in green tea, factors that affect how much caffeine is in each cup, and how it stacks up to other caffeinated drinks.
Why Green Tea Does Contain Caffeine
Green tea is made from the leaves of the Camellia sinensis plant, and since this plant naturally contains caffeine, so does the resulting tea. Unless the tea has undergone a decaffeination process, all types of green tea will contain some amount of caffeine. However, not all types of green tea will contain the same amount of caffeine.
“The caffeine content in green tea may vary depending on the type of tea,” says Jenna Volpe, RDN, LD, a registered dietitian in Austin, Texas. Varieties like matcha and sencha are examples of green teas with the highest caffeine content.
Factors that can affect the caffeine content in green tea include the water temperature during steeping, for how long the tea steeps, and the age of the tea leaves.
In terms of storage and environment, “time, light, and heat generally seem to degrade potency in herbs, so younger green tea leaves are usually higher in caffeine,” Volpe adds.
Using hotter water to make it and allowing the tea to steep for longer can have a significant impact on extracting (aka increasing) caffeine and other compounds in green tea, according to a 2021 study in Molecules.
The Caffeine Content in Green Tea Can Vary
An 8-ounce cup of brewed green tea contains around 28 milligrams (mg) of caffeine, according to the Mayo Clinic. But since the caffeine content in green tea exists on a spectrum, the FDA estimates an 8-ounce cup of green tea can contain anywhere from 30 to 50 mg of caffeine. There are many factors that can influence the caffeine content in green tea, as mentioned, however, so there may be cases where it’s even higher.
Matcha green tea, for instance, is highest in caffeine.
Matcha green tea, for example, contains the most caffeine of all the types of green tea, notes a 2020 review. “Matcha is a special type of green tea that involves grinding the tea leaves into a fine powder,” explains Maggie Moon, RD, a Los Angeles–based registered dietitian. “Because drinking matcha means consuming the whole leaf powder, it is higher in caffeine than simply drinking an infusion of green tea leaves.”
Researchers estimate that the caffeine in matcha falls between 18.9 and 44.4 mg per gram—nearly double that of regular green tea. A typical serving of matcha is about 2 grams, which would yield up to 88.8 mg of caffeine per cup.
Sencha tea is also a higher-caffeine green tea.
Sencha green tea, another popular Japanese green tea, is also higher in caffeine than your typical bagged and steeped green tea. There isn’t as much research on the compounds found in sencha compared to other teas, but sencha tea is believed to contain up to 75 mg of caffeine per cup.
If you're curious about the specific amount of caffeine in the green tea bags you have at home, most brands will include the caffeine amount on the packaging somewhere (on the box or canister, for instance). You can also usually find it by doing an internet search of the brand and its tea product for more information.
Yes, You Can Find Decaf Green Tea
If you’re wondering if decaf green tea is an option, it sure is! Some varieties of green tea undergo a decaffeination process to remove some of the caffeine after it’s been harvested. However, there’s no such thing as a truly caffeine-free tea—as with decaf coffee, trace amounts of caffeine may still be present after the decaffeination process, per the FDA.
How Much Caffeine Should You Have Per Day?
According to the FDA, the safe upper limit of caffeine for most adults is around 400 mg per day.
“It’s important to be aware of all food and drink sources of caffeine, including the caffeine in green tea, because caffeine is a psychoactive stimulant that affects people differently,” Moon says, adding that some people are more sensitive to caffeine than others. There are also groups that should limit their caffeine intake, such as children and women who are pregnant or breastfeeding.
Caffeine in Green Tea vs. Other Beverages
Caffeine is a stimulant and shouldn’t be consumed in excessive amounts. From your morning pot of coffee to your afternoon tea, and perhaps a soda with dinner or even a post-meal slab of chocolate, it’s easy to get doses of caffeine throughout the day. It can add up quickly, so here’s what you need to know about consuming caffeine in safe, healthy amounts.
Here’s how the caffeine in green tea compares to other beverages, per the FDA:
Green tea: 30 to 50 mg per 8 ounces
Soda: 30 to 40 mg per 12 ounces
Black tea: 30 to 50 mg per 8 ounces
Coffee: 80 to 100 mg per 8 ounces
Energy drinks: 40 to 250 mg per 8 ounces
Though there are exceptions, green tea tends to contain less caffeine than most popular caffeinated alternatives, Volpe says. And it’s usually gentler and has the added benefit of being free of added sugars, Moon adds.
Top Health Benefits of Green Tea
“On average, an 8-ounce cup of standard brewed green tea provides about 8 to 10 percent of the FDA’s daily recommended upper limit of 400 mg,” Volpe says. A couple cups of green tea per day can certainly perk you up in a healthy way, but that’s not all it has to offer. It’s also a good source of beneficial compounds.
For starters, it’s a great source of antioxidants, which help fend off free radicals that can damage healthy cells and contribute to disease. “The majority of green tea’s health benefits are attributed to its antioxidants, especially a catechin called epigallocatechin gallate (EGCG),” Volpe explains. These catechins may even inhibit some types of cancer, such as breast cancer, according to a 2020 review.
Green tea is also a source of an amino acid called L-theanine, which can influence mood and cognitive function. It’s commonly associated with reducing anxiety. “Research shows the combination of L-theanine and caffeine improves mental focus,” Moon says. Its anti-aging and cognitive benefits may even offer some protection against neurodegenerative diseases like Alzheimer’s, notes Volpe, referencing a 2019 review in Nutrients.
Of course, the caffeine itself proves beneficial in certain contexts and in moderation (no more than about 400 mg per day). Caffeine is touted as giving athletes a boost in athletic performance, Moon says, pointing to a 2021 review linking caffeine to increased exercise performance.
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