Green Tea: Benefits, Side Effects, and Preparations

Green tea

Verywell / Alexandra Shytsman

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Green tea has been used for medicinal purposes in China and Japan for thousands of years. This popular tea is known for its bittersweet taste and nutty flavor and is widely regarded for its energy-boosting qualities and health benefits.

What Is Green Tea?

Much like black or oolong tea, green tea comes from the Camellia sinensis plant and is offered in several varieties, which will range in different flavors and colors depending on growing methods, harvesting, and processing. But green tea differs from black or oolong because the green tea leaves are picked, steamed, and roasted raw. This halts oxidation to the leaves and preserves many of the essential nutrients and antioxidants.

The discovery of green tea dates back to 2737 BC and is attributed to the mythological Chinese emperor Shennong, an herbalist who, according to legend, established an early agricultural society in China. And while green tea is said to have originated in China, it also has roots in Japan and parts of Southeast Asia. China is the largest manufacturer of green tea, but it is also grown and produced in many countries around the world. Here are some of the most common varieties.

  • Sencha: The most commonly drunk and well-known variety of Japanese green tea is Sencha. The tea leaves are said to be of the best quality because they come from the first harvest. The leaves are steamed, dried, and rolled, releasing the juices within the leaves for an intense flavor.
  • Gyokuro: The harvesting process for Gyokuro green tea differs from Sencha as the green leaves are removed from sunlight about three weeks before harvest. Without direct sunlight, less photosynthesis occurs retaining strong-flavored amino acids. The tea leaves are steamed, dried, and rolled similar to Sencha; Gyokuro green tea has a richer flavor and is more costly given the additional steps to cultivate.
  • Tencha: As the main ingredient to matcha green tea, Tencha Similar to Gyokuro, the green leaves are removed from sunlight three weeks before harvest. The leaves are steamed but dried without being rolled. This gives the tea a pale green color and mellow flavor.
  • Matcha: When Tencha is stoneground it becomes matcha green tea. Once the green tea leaves are steamed and air-dried, stems and veins are removed and ground into a powder ready for brewing. Matcha green tea is a light green color with an intensely rich taste with a lingering sweetness.
  • Funmatsucha: Ground tea leaves usually not high quality and cheaper in price. The harvesting is different than Matcha in that it receives no protection from the sunlight. The end product is a green tea with a bitter flavor.
  • Fukamushicha: A combination of Sencha, Gyokuro, and Kabusecha green tea leaves, Fukamushicha green tea leaves undergo a deep steaming process creating a deep color and rich flavored green tea.
  • Konacha: This green tea is made from the small leaves left behind after Sencha and Gyokuro processing. It is less expensive because it is a natural byproduct of other tea production and does not need to be cultivated by itself. This green tea has an intense green color and a strong bitter taste.
  • Shincha: This translates to “new tea” because it comes from the first harvest of Japanese green tea. Only the young, tender leaves are harvested by hand, steamed, dried, and rolled. This means the green tea leaves are of the highest quality and the most expensive. The flavor is light and refreshing.
  • Bancha: Cultivated and processed the same way as Sencha, but comes from later harvests. This means the green tea is considered lower grade and because of that is more budget-friendly. It has a golden color and a nutty sweet flavor.
  • Kukicha: Also referred to as a twig tea, Kukicha is made from the stems and veins of tea leaves initially harvested for Sencha and Matcha green teas. It contains minimal caffeine, is yellow in color, and has a mild, creamy sweet flavor.

How to Prepare

There are many ways to make green tea, from iced to warm. Keep in mind that adding additional ingredients like milk or sugar may alter the nutrition content. You can prepare green tea just as you would prepare any other type of traditional tea. When possible, it's a good idea to use filtered water and a temperature-controlled teapot (if you have one) to regulate water heat.

5 Steps to Prepare Green Tea

  • Place a green tea bag or a tea infuser containing about one tablespoon of loose tea leaves in a teacup. You could also place loose tea leaves at the bottom of a cup and then strain them out once it's steeped.
  • Heat water to 90-95º Celsius or 194-205º Fahrenheit. Alternatively, simply bring water to a boil and then let it sit for a minute to reduce the temperature before pouring it over the leaves.
  • Once the water has cooled slightly, pour eight ounces of water into your cup over the tea bag, infuser, or leaves.
  • Let the tea steep for as long as you like, depending on whether you prefer a lighter or stronger brew. For a lighter tea, 2 minutes should suffice; for a stronger cup, try 3–5 minutes. Keep in mind that steeping for too long may produce an overly bitter flavor.
  • Before drinking, be sure to remove the tea bag or infuser or strain the loose leaves from the cup.

Tea purists recommend drinking green tea without any milk or sweeteners, though many people enjoy a touch of honey to sweeten the taste. If you prefer a bit of both, use a tablespoon or two of your milk of choice and sweeten with cane sugar, honey, or agave according to your taste preference.

Check out these recipes for delicious ways to prepare this popular health drink.

Caffeine Content

In addition to valuable antioxidants, green tea contains about 25mg of caffeine per cup. This means it has stimulant properties, but much less than a cup of black coffee containing between 95 to 165mg of caffeine per cup. That said, experiencing the jitters typical with higher caffeine doses from a cup of coffee is usually not associated with drinking a cup of green tea.

Health Benefits

Green tea is a popular nutritious drink associated with a healthy lifestyle. Because green tea contains valuable phytochemicals, it is shown to play a valuable role in disease prevention. In addition to containing less caffeine than a cup of coffee, green tea also provides minimal calories. Research has indicated green tea to be associated with a wide range of medicinal properties.

Many of the health benefits of green tea come from the antioxidants, polyphenols (micronutrients), and caffeine, found in the green leaves. In fact, green tea is said to be richer in antioxidants compared to other forms of tea.

The antioxidant-rich plant compounds making this drink so healthy are called flavonoids. The most common flavonoid in green tea is a catechin known as epigallocatechin gallate (EGCG). Green tea also contains theanine (L-theanine), an amino acid shown to reduce anxiety. Other antioxidants found in green tea leaves are called proanthocyanidins and may help reduce inflammation in the body.

Green tea contains trace amounts of vitamins but is a rich source of minerals including magnesium, potassium, and sodium. Other minerals found in green tea include chromium, calcium, zinc, and more, which may vary in concentration depending on the fermentation process, age, and size of the green tea leaves. Here's a close look at some of the research on the health benefits of green tea.

Lowers the Risk of Diabetes

Green tea contains the catechin epigallocatechin gallate (EGCG) as well as polyphenols. Research indicates that EGCG in green tea may help regulate blood glucose (sugar) in the body helping to prevent or control diabetes. Other studies claim green tea to improve metabolic function directly related to a lowered risk of diabetes. While there is conflicting evidence to support these claims, most research represents green tea as an attractive alternative to promoting human health.

Supports Heart Health

Several studies indicate green tea may have beneficial effects on cardiovascular health. The catechins in green tea, especially EGCG, decrease the absorption of triglycerides (fat) and cholesterol. The reduction of fat in the blood helps to prevent plaque buildup (atherosclerosis) reducing the risk of heart attack or stroke.

Improves Digestive Health

Research shows that drinking green tea can help prevent gastrointestinal disorders. The catechins (antioxidants) found in green tea are well absorbed in the gastrointestinal tract, where intracellular antioxidants are activated to improve digestive health.

Lowers Risk of Certain Cancers

The catechins and polyphenols in green tea may reduce the risk of various types of cancer. These powerful antioxidants are shown to activate detoxification enzymes that may help reduce tumor development. While green tea research is still ongoing, numerous studies indicate a reduced risk of certain cancers including prostate, lung, breast, colon, and liver cancers.

Decreases Inflammation

Green tea contains a unique set of catechins with significant antioxidant and anti-inflammatory properties, according to studies. Inflammation is a normal bodily response to injury, infection, or destruction where the body is trying to destroy invading organisms, remove irritants, and set the stage for tissue repair. Antioxidants contained in green tea are shown to significantly help with this repair and reduce inflammation.

Stimulates Weight and Fat Loss

Studies indicate green tea may help reduce body weight, mainly body fat. According to a small human study, green tea rich in EGCG has the potential to increase fat oxidation (burning) and contribute to the anti-obesity effects of green tea. Caffeine in green tea is also shown to increase fat oxidation and improve metabolic function, another contributing factor to weight loss.

Lowers the Risk of Neurological Disorders

Several studies have found green tea to have beneficial effects on the prevention and treatment of neurodegenerative diseases and impairment, including cognitive dysfunction and memory loss. Brain disorders such as Parkinson’s disease have also shown positive results with green tea consumption. It appears that the catechin EGCG in green tea helps prevent fibrous proteins associated with neurological disease to accumulate in the brain.

Reduces Stress and Anxiety

Green tea contains theanine (L-theanine), an amino acid shown to reduce anxiety and stress. According to a pilot study, the anti-stress effects work best when consuming low-caffeine green tea. Some studies indicate green tea with combined theanine and caffeine at normal levels still produced a reduction in anxiety. Either way, it appears green tea has a positive effect on lowering stress and anxiety, in general.

Helps Anti-Aging

Green tea phytochemicals contain potent antioxidants that may reduce premature aging of the skin. Several studies suggest green tea consumption increases the collagen and elastin fiber content and suppresses collagen degrading enzyme (MMP-3) production. Although the exact mechanism behind the anti-aging effects is unclear, green tea appears to promote an anti-wrinkle effect.

Improves Oral and Dental Health

Green tea polyphenols protect against bacterial tooth decay and plaque buildup, according to studies. The plant compounds in green tea are said to control bacteria and lower acidity levels in saliva and dental plaque. Because of these results, research indicates that drinking green tea is a useful tool in cavity prevention. Green tea is also shown to reduce halitosis (bad breath) since EGCG provides a deodorizing effect by reducing odorant sulfur components.

Side Effects

Green tea is shown to have numerous health benefits when consumed in moderate amounts. However, research indicates higher doses may have the potential to cause some known and unknown adverse effects.

For instance, the catechin EGCG can be toxic to living cells in higher doses. For example, higher consumption of green tea above 800mg daily may pose a potential risk of liver damage. A single cup of brewed green tea typically contains between 50-100mg EGCG.

The caffeine content in green tea has stimulant properties with the potential to cause adverse health effects in certain people. Research indicates green tea should not be consumed by patients suffering from heart conditions or major cardiovascular problems. People who are pregnant or nursing should drink no more than one or two cups daily because caffeine can cause increased heart rhythm and other complications.

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