Green Tea: Benefits, Types, & Side Effects

by Meenakshi Nagdeve last updated - Medically reviewed by Zemira Barnes (MS)

The many well-researched health benefits of green tea make it a great beverage to include in your diet for the prevention of cardiovascular diseases, high cholesterol levels, rheumatoid arthritis, infection, tooth decay, and many others. Green tea contains an antioxidant called epigallocatechin-3 gallate (EGCG).

What is Green Tea?

Unbeknownst to many, green tea comes from the same plant from where normal tea is obtained. Scientifically known as Camellia Sinensis, it is the same tea with a different process. Furthermore, green tea leaves are freshly harvested and quickly steamed to prevent fermentation, resulting in a dry stable product. During that steaming process, the leaves’ color is undisturbed allowing the tea to maintain its green color. [1]

Green tea is useful for depression, non-alcoholic fatty liver disease (NAFLD), inflammatory bowel disease, and weight loss. It also helps ease stomach disorders, vomiting, diarrhea, headaches, and may reduce osteoporosis (bone loss). [2]

Nutrition Facts

Beverages, tea, green, ready to drink, unsweetened
Serving Size :
Water [g]99.88
Ash [g]0.12
Calcium, Ca [mg]1
Phosphorus, P [mg]26
Potassium, K [mg]19
Sodium, Na [mg]7
Zinc, Zn [mg]0.01
Copper, Cu [mg]0.01
Caffeine [mg]12
Sources include : USDA [3]

Green Tea Nutrition

According to the USDA FoodData Central, drinking 1 cup of green tea (245 g) provides 2.4 kcal. it also has B vitamins, iron, potassium, sodium, and zinc, and contains no sugar and dietary fiber. Along with 29.4 mg of caffeine, green tea is also rich in a group of chemicals, called polyphenols. These polyphenols include: [4]

  • Flavonols, flavonoids, and phenolic acids.
  • Tannins, a type of polyphenol that contributes to the bitter taste and astringency in tea.
  • Flavonoids such as epicatechin, epicatechin 3 gallate (ECG), and epigallocatechin gallate (EGCG).
  • Amino acids like thiamine that are responsible for the potent flavor of green tea.
  • Green tea also contains amino acids such as theanine, tyrosine, and leucine, xanthine alkaloids such as adenine, dimethylxanthine, theobromine, theophylline, and xanthine; carbohydrates such as pectin (also found in fruits), along with glucose, sucrose, and fructose; pigments such as chlorophyll, and triterpene saponins.
  • Vitamins, like vitamins A, B1, B2, B3, C, and E are also found in green tea.

Green Tea Health Benefits

The health benefits of green tea have antioxidant properties that come from its caffeine, catechin polyphenols, and theanine content. The primary health benefits stemming from its antioxidant content are listed below.

Delays Aging

The free radicals are responsible for destroying the body in various ways, seen as the signs of aging and its related symptoms. Antioxidant-rich green tea neutralizes the oxidants or free radicals present in the body. The catechin polyphenols present in it are hugely responsible for antioxidizing effects and the most potent among them being the epigallocatechin gallate, says a report published in the International Journal of Vitamin and Nutrition Research. Therefore, regular consumption of this tea can effectively delay the signs and symptoms of aging. You can read more about green tea’s benefits for skin and hair, here. [5]

Has a Stimulating Effect

One of the primary reasons for the popularity and consumption of all kinds of tea by human civilizations is its stimulating effect. This effect is due to the caffeine present in the tea leaves. Caffeine and tannins, despite their potentially adverse health effects, act as strong stimulants.  This is why it is so popular with various people in different industries, from professionals to students, and anyone who feels a bit drowsy! [6]

Green tea being poured from a kettle in a white cup that is kept on a green mat

Green tea is an ideal addition to a weight loss diet. Photo Credit: Shutterstock

Boosts Immunity

Research shows that people who regularly drink green tea do not fall victim to common bacterial and viral infections as it boosts the immune system. The catechins, present in green tea, prevent bacteria and viruses from attaching themselves to cell walls to infect them. These catechins also counter the toxins released by microbes. This antimicrobial property protects you from bad breath, dysentery, diarrhea, tooth decay, and flu caused by the microbial and fungal action. [7]


Astringent substances trigger contractions in muscles and tissues while toning up muscles and skin. Even if you do not wish to drink this tea, a simple, daily mouthwash with it can cause sufficient contraction in your gums to keep them firm and tight on the teeth, thus preventing loosening and loss of teeth. Also, rubbing green tea onto your scalp not only increases hair growth but also reduces inflammatory issues, such as dandruff and hair fall. [8] [9]

Improves Cardiac Health

Specific components in green tea lower blood pressure reducing the risk of stroke and coronary heart disease. According to Atherosclerosis Journal, green tea increases the antioxidant capacity of the blood exponentially, which prevents the LDL particles from oxidation (one of the reasons that cause heart disease). [10] [11]

Moreover, green tea is effective in lessening cholesterol levels to some extent according to a study published in the Cochrane Database of Systematic Reviews. [12]

Manages Diabetes

The alkaline nature of green tea helps reduce the blood glucose level. Moreover, the antioxidant properties of green tea ensure good health and better functioning of the pancreas. A 2014 study published in the Integrative Medicine Research Journal has shown that EGCG in green tea has an inhibiting effect on the development of diabetes. However, green tea consumption is high enough to raise concerns about side effects. So, it is necessary to be mindful of the quantity of green tea taken in a day. [13] [14]

Weight Loss

Green tea also helps people lose weight by enhancing the metabolism rate of the body. According to a study in the Molecules journal, a cup of green and black tea shows significant results in weight loss. Drink a cup or two of green tea every morning and you are bound to lose a few pounds of excess weight over a week or so. More so, it even boosts stamina and builds endurance. You can read more about how green tea helps you lose weight easily.

Detoxifies the Body

Green tea eliminates savage hangovers and fatigue caused by alcohol and lack of sleep. Cure your hangover with a large cup of green tea with lemon, and the hangover will begin to fade. Green tea with lemon juice is a popular remedy to eliminate the after-effects of consuming alcohol instantly. [15]

Types of Green Tea

Green tea has four main varieties prepared in Japan, which depend upon its leaf-length, method of processing, and harvest season. They are as follows:

  • Gyokurocha: In this variety, the tea leaves are plucked from the tip of the branches. When brewed, the color is transparent green. Furthermore, it is less bitter, as it contains lesser tannin and caffeine since the plucked leaves are younger and still budding. The only drawback to gyokurocha is the high cost.
  • Sencha: Sencha comes from the same plant, but in this green tea variation, the leaves are from the middle of the branch and are significantly older, and less tender than Gyokurocha. This variety gives a clear, light green tea when brewed as well. Naturally, it is bitter and more robust than the former type. Being of less noble origin (middle of the branch) and having more caffeine and tannin, it is cheaper and more popular than Gyokurocha.
  • Bancha: Bancha is the tender twigs of the tea plant which makes it very strong and bitter. When brewed, it gives a golden brown tea, a cheaper version of green tea than the previous two.
  • Matcha: This is the leftover powder of green tea, also called “dust”. It makes a beautifully green-colored tea and forms a lot of foam (froth), but has a weaker aroma than the leafy varieties. This variety of green tea is prominent in traditional ceremonies and is sometimes also called Ceremonial Green Tea. It is far less bitter than the other three types, so when you sip it, it seems to hold a natural sweetness, especially if you are familiar with the different types.
  • Houjicha: Also spelled as “Hojicha”, this is not a pure or absolute green tea. Instead, it is a mixture of green tea and powdered roasted cereals such as wheat, barley, or rice. This variety’s quality and price depend upon the percentage or ratio of green tea to cereal content. The better ones, which have more green tea in them, are more expensive and have a greener look when brewed; on the other hand, those with higher grain contents yield a golden brown color and are cheaper.
  • Genmaicha: It is a mixture of green tea and roasted brown rice. Upon steeping, it yields a golden yellow tea, delightful in both taste and aroma due to roasted brown rice.
  • Decaffeinated Green Tea: This is not a specific variety, but it is worth mentioning here. Any of the above types can come in a decaffeinated form.
  • Other Varieties: The chief varieties mentioned above are blended in different combinations to produce many more varieties with different names.

Side Effects

The risks associated with green tea are primarily due to the caffeine and tannin content. The contraindications may vary with the percentage of caffeine and tannins in it. [16]

  • Caffeine: Everyone knows that caffeine is an external stimulant and raises blood pressure, and is toxic (it may be fatal for some animals). Caffeine is also addictive and can have adverse effects on the liver and internal organs over many years. [17]
  • Tannins: Tannins interfere with the breakdown of complex proteins into simpler proteins and their subsequent absorption into the body.
  • Xanthine alkaloids: Some researchers believe that these alkaloids aggravate and stimulate uric acid formation in the body, thereby triggering and helping the formation of stones in the gallbladder and kidneys.
  • Other risks: When you consume green tea in excess, it may give rise to insomnia, restlessness, irritability, loss of appetite, constipation, and acute caffeine addiction.

Availability of Green Tea

Asian countries like Japan and China are the biggest producers of green tea (they produce the best quality) and are also its biggest consumers. Green tea available in other markets is found in far smaller quantities than black tea. Moreover, it is still gaining popularity, and you can get it at any modern shop. You can also order it from a local tea supplier, over the phone or on the internet. It is almost invariably imported from China (cheaper) and Japan (more expensive) and is packed in sealed packs of 200 grams, 250 grams, and 500 grams. Buy smaller quantities if possible, so that you get to make a fresh brew. Also, always check the date of manufacturing and packing before you buy it.


What is green tea good for?

Green tea is rich in antioxidants and nutrients. It has powerful health benefits which include weight loss, enhanced stamina, improved cardiac health, and potentially reduced risk of diabetes. It also has anti-aging properties and is used as an immunity booster. Moreover, it is used as an astringent and to detoxify the body.

Can green tea be consumed before bed?

Green tea is said to have a component known as theanine, which is said to be the primary sleep-promoting compound in it. According to a 2010 report in the Journal of Food Science, caffeine’s effects take as less as 20 minutes to become visible and almost 1 hour to reach its full efficacy. This means a cup of green tea could potentially disrupt a person’s sleep if one is sensitive to caffeine. These people benefit from drinking low-caffeinated green tea. It is always advisable to drink caffeinated green tea either throughout the day or at least two hours before bed to avoid disrupting one’s sleep. [18]

Is green tea acidic?

The alkaline and acidic level are not the same in all types of tea. While green tea has a less acidic level, lemon tea has the highest. So, if one is looking for a safe option, they should go for the one that has more pH levels. More pH levels equal less acidic levels and higher pH means more alkaline.

How is black tea different from green tea?

The regular black tea is obtained by fermenting the tea leaves. This fermentation changes its color and flavor while raising the level of caffeine and tannin in it. Protection Status
About the Author

Meenakshi Nagdeve, Co-Founder, Organic Facts is a health and wellness enthusiast and is responsible for managing it. She has completed the Nutrition And Healthy Living Cornell Certificate Program, Cornell University, US. She holds a Post Graduate Diploma in Management from IIM Bangalore and B. Tech in Metallurgical Engineering and Materials Science from IIT Bombay. Prior to this, she worked for a few years in IT and Financial services. An ardent follower of naturopathy, she believes in healing with foods. In her free time, she loves to travel and taste different types of teas.

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