Caffeine in Green Tea Vs. Coffee

Caffeine, thought to be the world’s most frequently consumed stimulant drug according to 2015 research published in "Current Neuropharmacology," occurs naturally in some foods and beverages like coffee, tea, and chocolate.

Both green tea and coffee contain caffeine. (Image: DevMarya/iStock/GettyImages)

While green tea and coffee both have caffeine, coffee has a significantly greater amount per cup. Coffee and green tea have other nutrients in them that have been linked with significant health benefits.

However, with any caffeinated beverage, there may be health risk. Certain populations should reduce or avoid caffeine for health reasons, so decaffeinated tea or coffee may be the best option.

Effects of Caffeine

Caffeine has been consumed for hundreds of years and studies have gone back and forth on whether or not caffeine is safe.

Because of its classification as a stimulant, it effects the central nervous system and is used to increase alertness, concentration, and athletic performance, according to 2015 research published in "Advances in Nutrition."

Caffeine is also a diuretic and can lead to increased urination and possibly dehydration. Caffeine can also be isolated and is used in medications for headaches, appetite, pain relief, and asthma.

Green Tea

If you drink a cup of green tea every day, you are receiving a relatively small dose of caffeine. Eight ounces of green tea contain about 35 mg of caffeine, which is about half the amount of caffeine found in regular, black tea.

However, this is still more significant than decaffeinated tea, which has between 2 to 10 mg of caffeine per cup. Even iced green tea has caffeine, about 15 mg in a 16 ounce container. Exercise caution when drinking iced green tea or green tea lattes, as they can be loaded down with added sugar and contribute to extra calories.


The average cup — 8 ounces — of coffee has about 100 to 200 mg of caffeine. You would need to drink at least three cups of green tea to get the same amount of caffeine as one cup of coffee.

In comparison, a popular anti-sleep aid has about 200 mg of caffeine per tablet. Drinking a cup of decaffeinated coffee provides you with about 2 to 12 mg of caffeine. Interestingly, a 1 ounce shot of espresso has only about 60 to 75 mg of caffeine, so a 16 ounce latte has about the same amount of caffeine as 8 ounce of coffee, but well over 200 calories from added milk and sugar.

Comparing Coffee and Tea to Other Caffeine Sources

In general, coffee may have more caffeine per 8 ounce cup than 1 can of regular cola, depending on how the coffee was brewed. Conversely, green tea has less caffeine than coffee or soda. Coffee and tea can provide you with additional naturally occurring nutrients while most sodas and energy drinks only have added sugars and artificially added vitamins.

According to the "British Journal of Nutrition," coffee can provide significant levels of essential nutrients like niacin, magnesium and potassium. In addition, moderate coffee consumption has shown to have a positive impact on antioxidant levels, neurological disorders, metabolic disorders and liver function.

According to the "Journal of the American College of Nutrition," the polyphenols, flavonoids and antioxidants naturally found in green tea have been associated with improved body weight control and reduced risk of cardiovascular disease and some forms of cancer.

Potential Side Effects

Drinking a couple of cups of coffee each day is generally considered safe. In fact, research suggests that 85 percent of U.S. adults regularly consume caffeine from different sources, according to "Frontiers in Psychiatry."

Consuming large amounts of caffeine, more than 500 to 600 mg per day, in either food or pharmaceutical form can lead to symptoms including restlessness, irritation, disturbed sleep cycles, and abnormal heart rhythms.

In addition, if you are sensitive to caffeine, pregnant or nursing you may want to consider limiting your caffeine intake. Caffeine consumption during pregnancy has been linked to preterm birth and low birth weight according to 2017 research published in "The BMJ."In addition, caffeine has been shown to interact with some medications, so speak to your physician about any significant changes in caffeine intake.

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