Turns Out Drinking Too Much Green Tea Can Be Seriously Harmful

A nutritionist and gastroenterologist weigh in.

close-up of a tea cup being held by a woman

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We know that green tea is packed with antioxidants and health benefits, like boosting your metabolism and giving you a nice, even energy boost sans the mid-afternoon coffee crash. Not to mention, nothing beats curling up and sipping on a warm cup of this soothing beverage.

But it turns out there can be too much of a good thing in this case. For some, drinking excess amounts of green tea can lead to iron deficiency—and for one 16-year-old, drinking three cups of green tea per day as part of a weight-loss plan may have led to herb-induced hepatitis—yikes! To find out why these things can happen, we chatted with NYC-based nutritionist Jennifer Maeng and NYC-based gastroenterologist Niket Sonpal. Keep reading to learn why they say drinking large amounts of green tea can be harmful.

Meet the Expert

  • Jennifer Maeng, MS, RD, CDN, CNSC, is a New York City-based nutritionist, former chef, and restaurateur that uses her clinical and culinary knowledge to help clients make lasting lifestyle changes.
  • Dr. Niket Sonpal is a Brooklyn-based gastroenterologist. 

What Is Green Tea?

Green tea comes from the Camellia sinensis plant, an evergreen shrub that grows mainly in China and India. While black tea and green tea come from the same plant, they are processed differently. Post-harvest, the leaves for green tea are quickly steamed or heated to stop oxidation. However, black tea leaves are crushed or rolled and given time to oxidize before being dried. Pretty cool, right? 

Is Drinking Green Tea Safe?

First things first, let's get one thing straight: Drinking green tea in moderate amounts is nothing to be concerned over. The antioxidant-rich beverage has been a staple in diets for thousands of years. The drink is also proven to lower cholesterol levels, reduce the chance of coronary artery disease, protect against oxidative stress, and soothe inflammation. That said, it is only problematic when consumed in large quantities.

If you're worried about whether you need to stop sipping green tea immediately, Sonpal says there's no need to fret: "Green tea is incredibly safe for the most part," he explains. "It's rare for hepatotoxicity to occur with daily normal consumption, like one or two cups." The damaging effects happen if you drink green tea religiously throughout the day.

"At Chelsea Nutrition, we consider seven cups (8 ounces per cup) of green tea (from a teabag) a little too high," Maeng says. "For our clients who love green teas, we recommend no more than four cups per day and no more than 1.5 ounces of matcha per day." As a reminder, Maeng says that matcha (which is a potent form of green tea) is made from whole leaves and can contain much, much, much more caffeine than green tea from a teabag.

At the end of the day, to find out how much green tea is too much, speak to your doctor since everybody breaks down the compounds in foods and herbs differently.

Green Tea and Caffeine Sensitivity 

If you have ever felt any jitters or nervousness, shortly after a cup of green tea, you may be sensitive to caffeine even in low doses. So monitoring your body after a cup can help you decide if you need to drink less or find an alternative like an herbal tea. While herbal teas don't come from the same Camellia sinensis plant as green tea, they can still yield many health benefits.

For example, chamomile tea has anti-inflammatory benefits like green tea but can be an excellent bedtime nightcap to help you sleep. And, if you're looking for a drink that can help with digestion similar to green tea, ginger tea can help soothe nausea, morning sickness, and motion sickness. 

Green Tea and Iron Deficiency

While experiencing adverse effects from green tea isn't super common, it's worth understanding why an excess can lead to an undesirable result. According to Maeng, green tea is high in EGCG (catechins) and tannins. "Too many tannins from green tea can reduce iron absorption in your body and lead to iron deficiency," she explains.

Green Tea and Herbal Hepatotoxicity

In the instance of the 16-year-old girl, the condition is known as herbal hepatotoxicity, which happens when too many herbs or supplements are ingested, thus leading to toxin-induced hepatitis. Just like the labels on painkillers warn, sipping too much green tea can have the same liver-damaging effect.

The ingredient in question is catechin, a natural phenol, and antioxidant. While catechin is a powerful anti-inflammatory, drinking too much of the ingredient can greatly harm your liver: "When you start taking the extracts and boiling them down into concentrated capsules, it's kind of like little, tiny bombs going into your liver," Sonpal says. Sounds incredibly scary.

The Final Takeaway

The majority of the time, drinking a couple of glasses of green tea isn't a cause for concern. However, if the low chance of developing one of these issues is enough to make you want to set your green tea habit aside in search of a new healthy beverage, we recommend the Asobu Stainless Steel Flavor U See Infuser Water Bottle ($20). Water flavored with pure, fresh fruit tastes great, delivers vitamins, and keeps you hydrated all day long—all while being relatively benign and nearly impossible to overdose on. And with hydration comes a healthy glow. So, drink up!

asobu Flavor U See a Stainless Steel Fruit Infuser
Asobu Flavor U See a Stainless Steel Fruit Infuser $20

Up next: Discover eight health benefits of drinking peppermint tea.

Article Sources
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  3. Srivastava JK, Shankar E, Gupta S. Chamomile: a herbal medicine of the past with bright futureMol Med Rep. 2010;3(6):895-901. doi:10.3892/mmr.2010.377

  4. Teschke R, Frenzel C, Glass X, Schulze J, Eickhoff A. Herbal hepatotoxicity: a critical reviewBr J Clin Pharmacol. 2013;75(3):630-636. doi:10.1111/j.1365-2125.2012.04395.x

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