Green Tea 101: A Complete Guide

pouring green tea
Antioxidant-packed green tea may help prevent cancer and aid in weight loss, among other potential health benefits.Dejan Beokovic/Stocksy

Water is the most-consumed beverage in the world, but occupying the No. 2 spot is tea, according to 2019–2020 data from the Tea Association of the USA. More than 159 million Americans have this brewed beverage every day, and no wonder: Tea can be enjoyed hot or cold, and comes in different varieties for different tastes. Plus, tea has been well studied for its health benefits, particularly green tea. This guide explores all the reasons why green tea is good for you, as well as ways to drink more.

What Exactly Is Green Tea?

All tea comes from the same plant, Camellia sinensis, but the leaves are processed differently to make green, black, and oolong tea, according to the National Center for Complementary and Integrative Health (NCCIH). Green tea leaves are steamed, which accounts for their fresh, almost grassy flavor.

Tea-drinking is a ritual that people have been practicing for centuries, dating back to B.C. 2737 in Asia, according to some accounts. It is known for its high content of antioxidants called catechins (more on those later) and beloved for its crash- and jitter-free dose of caffeine, which is thanks to its generous supply of L-theanine, an amino acid that research has found to have a calming effect on the nervous system. Melissa Salazar, an International Tea Master Association–certified tea master, says that green tea has the highest quantity of L-theanine compared with other teas. “It helps to increase brain waves, which induces deep relaxation and increases focus,” she adds. “This makes green tea a very special plant indeed.”

Some small studies have observed this as well, finding that L-theanine increased alpha wave emission in people with anxiety and improved mental alertness. A study of 69 Japanese men and women published in 2021 in the Journal of Medicinal Food found it to improve attention and memory-related tasks.

With that being said, some green tea blends have more caffeine than others. Matcha, a popular powdered form of green tea, has the most. That’s because it’s made by grinding the entire Camellia sinensis leaf, explains Salazar, and is delivered to the body in its entirety, as opposed to tea leaves that are steeped in water and then removed prior to serving. Matcha’s unique preparation also makes it more plentiful in the good stuff, like antioxidants.

Today, green tea is still most commonly sipped in drink form, but it’s also finding its way into supplements, skin care, and more.

Common Questions & Answers

Is green tea good for you?
Absolutely! Green tea is packed with compounds called catechins, which have been shown to have extensive health benefits, including reducing the risk of developing cardiovascular issues.
How does green tea stack up compared with other caffeinated beverages?
In 8 ounces of green tea, there are between 30 and 50 milligrams (mg) of caffeine, roughly half the amount found in the same volume of coffee (80 to 100 mg) and around the same as you’ll find in 12 ounces of caffeinated soda (30 to 40 mg).
Will green tea help you lose weight?
Green tea isn’t directly correlated with weight loss — in fact, studies have shown that it doesn’t have a direct slimming effect. However, it’s never a bad idea to sub plain, unsweetened green tea for sugary soda, juice, or high-calorie coffee drinks as a part of your weight loss plan.
How do you make green tea?
It depends on the variety, but for traditional loose-leaf green tea, experts recommend combining 1 teaspoon of leaves per 6 ounces of just under boiling water and allowing it to steep for one to two minutes.
Is matcha the same thing as green tea?
No. Matcha is made from mixing finely ground whole green tea leaves with water, while traditional green tea steeps the leaves in water and discards the leaves afterward. For this reason, matcha is more concentrated in flavor and nutrients than other forms of green tea.

Matcha Two Ways: Latte and Tea

Everyday Health staff nutritionist Kelly Kennedy, RDN, shows you how to use matcha to make tea and a latte.
Matcha Two Ways: Latte and Tea

What’s in Green Tea? A Look at Its Nutrition Facts

Brewed green tea is primarily water based, which means it’s free of the usual macronutrients found in other foods and drinks. It doesn’t contain any fat, carbohydrates, or protein, and there aren’t any calories in unsweetened tea. It gets its healthy reputation from compounds called catechins, specifically epicatechin, epicatechin-3-gallate, epigallocatechin, and epigallocatechin-3-gallate (EGCG). These catechins have anti-inflammatory and anti-cancer effects, according to a review published in March 2020 in the International Journal of Molecular Sciences. They’re also believed to have probiotic benefits, per a study published in Nutrients.

A cup of green tea has around 28 milligrams (mg) of caffeine, which puts it slightly behind black tea’s 47 mg, according to the Mayo Clinic. However, there can be a lot of variation in caffeine content depending on how tea is processed and brewed.

The amount of catechins per cup also varies, with a systematic review stating a range of between 25 and 750 mg per cup.

What Are the Possible Health Benefits of Drinking Green Tea?

Green tea's benefits may include:

Can Green Tea Aid Weight Loss? What the Science Says

You’ve probably heard that sipping green tea can turn your body into a fat-burning machine. The thinking is that the caffeine and catechins in tea work together to send the metabolism into overdrive, which helps the body burn calories and, as a result, drop pounds.

It sounds too good to be true — and it is. These claims come from studies that presented green tea as the secret to weight loss, but most of them were small and short term, and often involved green tea extract rather than cups of brewed tea. Unfortunately, expecting green tea to produce a significant change in your waistline isn’t realistic.

“Evidence from clinical trials is mixed in their findings of weight loss associated with green tea consumption,” says Caroline West Passerrello, RDN, a licensed dietitian nutritionist and spokesperson for the Academy of Nutrition and Dietetics. “Extracts that are rich in ECGC may increase calorie and fat metabolism (maybe because of the catechins, caffeine, and theanine), and it might suppress appetite in animal research. Impact remains undetermined with well-designed studies.”

A study published in BMC Complementary and Alternative Medicine analyzed the effects of green tea extract on overweight women with high LDL levels compared with those taking a placebo. After six weeks, there were no significant changes in participants’ weight. Additionally, a review of 15 clinical trials published in Nutrición Hospitalaria found that green tea was effective for weight loss only when combined with 80 to 300 mg of caffeine per day.

On its own, however, plain, unsweetened green tea is a low-calorie beverage that is part of a sensible diet and will save you calories when swapped for sugary soda, juice, or high-calorie coffee drinks.

How to Select Green Tea

The type of green tea you choose will depend on the benefits you’re seeking, explains Salazar. If you’re looking for max caffeine and antioxidants, she says that matcha is your best bet. You can also steep the leaves of your favorite Chinese variety, she adds. It’s all a matter of trial and error to find what you like.

Like other teas, green tea is available loose, which requires a tea infuser or strainer to brew, or in sachets and tea bags.

You can also find green tea in dozens of products:

  • Powders
  • Bottled beverages
  • Supplements
  • Weight loss products

Experts caution not to overdo the supplements and weight loss products because the U.S. Food and Drug Administration (FDA) doesn’t regulate them. Everything else, though, is relatively safe.

If weight loss is your goal, be sure to check the ingredient label of green tea beverages. Regular, unsweetened tea is always a better bet than the sweetened bottled versions, which may have loads of added sugars. Unsweetened Green Tea from Pure Leaf, for instance, has 0 calories and 0 grams of (g) sugar in 18.5 ounces, while Arizona Green Tea packs 130 calories and 34 g of sugar into 8 ounces. Keep in mind that sweetened teas often come in larger portions than the unsweetened variety, so they have a greater potential to lead to weight gain.

How to Brew Green Tea

Preparation varies slightly depending on the tea type, as well as taste preference. But it’s important to know that overall green tea is sensitive to high temperatures and can get bitter if boiled, per Salazar. “The general rule of thumb is that you use a lower temperature than boiling,” she explains, which is anywhere from 150 to 175 degrees Fahrenheit.

“I like to brew my matcha at 165 degrees,” she adds. “How delicate the leaves are will determine the actual steeping time.” She recommends measuring out 1 teaspoon of leaves per 6 ounces of water, then steeping for one to two minutes. If you want to enjoy your cup cold, no need to worry about sacrificing its benefits. Salazar says that they don’t really wane from hot to iced. “For iced tea, you would simply steep the tea as you would and then pour over ice,” she adds.

What Are the Possible Side Effects of Drinking Too Much Green Tea?

Although green tea is generally considered safe and healthy, thanks to its many proven benefits, as with any food or drink, there can be too much of a good thing. Because green tea contains caffeine, drinking too much of it can lead to classic signs of caffeine overconsumption, such as feeling jittery and having trouble with sleep, per the NCCIH.

Consuming green tea in the form of concentrated extracts can end up damaging the liver. A study published in Cancer Prevention Research found that women who took a high dose of green tea extract (equivalent to five cups of brewed tea) daily developed high levels of liver enzymes, which could indicate that the cells within the liver have been damaged.

The take-home message? Approach green tea extracts with caution because they’re not regulated by the FDA. But if you decide you want to try them, experts recommend taking them only with meals and stop taking them and see a doctor if you notice signs that your liver’s in trouble, such as if you have especially dark urine or experience abdominal pain.

Also, stay away from green tea if you have a heart condition or other cardiovascular problems, or renal failure. For anyone who is pregnant or breastfeeding, up to six cups of green tea per day has been found to be safe, according to the NCCIH. It’s a good idea to consult your healthcare provider for individual recommendations.

Other Uses for Green Tea

You may spot green tea as an active ingredient in skin-care products because its anti-inflammatory properties and antioxidants make it an effective multitasker, according to Marisa Garshick, MD, a board-certified dermatologist at Manhattan Dermatology and Cosmetic Surgery and adviser to BioRepublic. Some research has found that the polyphenolic compound EGCG in green tea has antimicrobial activity, which may help inhibit the growth of bacteria that cause some difficult to treat skin infections.

The polyphenols in green tea may also prevent sun damage with their anti-inflammatory and antibacterial properties, a study found. And specific polyphenols called catechins have been found to have a moisturizing effect on skin, which may help reduce the appearance of fine lines, age spots, and wrinkles. “It’s a powerful antibacterial agent for treating acne and unclogging pores,” Garshick adds, although only small, limited studies have been done on this topic, and further research is necessary.“Green tea is chock-full of vitamin B2 and vitamin E, both essential for skin health.”

Summary

Green tea is a plant-based beverage that has been used medicinally for centuries and has plenty of research to back up its health-boosting properties. Its high concentration of antioxidants and versatility make it a popular drink as well as an ingredient to add to other foods and wellness products. Because it contains caffeine, it is important to use caution with supplements and extracts, and only use them in the recommended amounts.

Additional reporting by Kayla Blanton.

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