10 Health Benefits of Green Tea (And When to Avoid It)

Tea is the most widely consumed beverage in the world second to water. Tea leaves can be classified into different forms, but the clear winner will always be green tea owing to its rich composition and tremendous benefits. There is a lot more to a cup of green tea than its mild flavor, characteristic bitterness, and stimulating effect.

The origin of green tea can be traced back to its roots in the Yunnan Province of China, home to about 260 species of tea. Unlike in the West, the word “tea” in China refers specifically to green tea.

According to a popular myth, the discovery of tea as a beverage was documented around 2737 BC during the reign of Shennong, the then Emperor of China, when a few tea leaves from a nearby tree of the Camellia sinensis fell into his cup of boiled water and gave it a dark color and a refreshing taste.

Some legends around 500 BC accredited the discovery of tea to the Buddhists traveling between India and China. They spread the ritual of tea as a substitute for alcohol and soon tea ceremonies became a spiritual and social practice across China.

Processing Of Green Tea

Green tea is prepared from the leaves of the Camellia sinensis plant, the same plant that gives us the natural flavors of black and oolong (wulong) tea. The marked difference in the nutritional profile of green tea is due to the difference in processing.

Unlike the fermentation method for black tea leaves, green tea is processed by a steam drying method that preserves its antioxidant content. The level of antioxidants is determined by the quality of tea, the method of brewing, and the time of brewing. The antioxidant profile is higher in dry leaves than in brewed ones.

The tea leaves are harvested, heated by steam or pan fried, and dried to prevent oxidation of the leaves. This method is the reason behind the pool of tremendously beneficial nutrients and health benefits green tea boasts.

Although all teas contain antioxidants, green tea reportedly contains it the most in the form of catechins. Once you let the tea leaves steep in the boiling water, the bioactive compounds diffuse in, and the result is a drink effused with antioxidants.

Nutritional Content of Green Tea

Green tea packs a punch of bioactive compounds that contribute to its overwhelming health benefits on the human body.

Green tea is composed of a multitude of biochemical compounds, including polyphenols, caffeine, alkaloids, and B vitamins. The stimulating effect of green tea is attributed to caffeine, theobromine, and theophylline.

Green tea also contains L-theanine, an amino acid known to have soothing effects on the nervous system.

Popularly known for its high concentration of powerful antioxidants called polyphenols, green tea has been reported to work wonders against oxidative damage.

The polyphenols in green tea include catechin, epicatechin, epicatechin gallate (ECG), epigallocatechin gallate (EGCG), and various proanthocyanidins, which majorly contribute to the health benefits of green tea. The antioxidant action reduces the formation of free radicals in the body, which are known to cause damage at the cellular level.

Nutritional value of brewed green tea per 100 grams:

Water g 99.93
Caffeine mg 12
Energy kcal 1
Protein g 0.22
Niacin mg 0.030
Iron, Fe mg 0.02
Magnesium, Mg mg 1
Potassium, K mg 8
Sodium, Na mg 1
Riboflavin mg 0.058

Brewing Green Tea – The Standard Way

  1. Boil water in your teapot. Do not overboil the water. The ideal temperature is between 160 F and 180 F. This ensures that the bioactive ingredients in the green tea leaves remain intact. Remove it from the flame.
  2. Place your tea leaves or tea bag in the teapot.
  3. Let it steep for about 1–3 minutes. At this point, you can also add any fresh herbs in your tea to enrich the flavor.
  4. Once brewed, evenly pour a little amount of tea at a time into each cup to evenly distribute the nutritional strength of the tea. Add a few drops of lemon juice or a dash of honey if desired.

Benefits of Green Tea

The health benefits of green tea largely stem from a handful of antioxidants, notably flavonoids. These antioxidants are required to protect your body cells from free radicals.

Outlined below are some of the health benefits that green tea offers.

1. Helps Maintain Body Weight

Those who are health conscious or trying to lose weight can consume green tea for its weight loss benefits and positive overall health effects.

Animal-based studies have shown that green tea controlled blood cholesterol and fat mass gain in high-fat-diet-induced obese rodents. Some, but not all, human studies also suggest that green tea may have a beneficial role in weight loss.

A study supports the minor but synergistic impact of catechins and an EGCG-caffeine mixture on body weight by considering the parameters of weight management and weight loss. It was suggested that the effect of catechins may be influenced by the moderating factors of habitual caffeine intake and ethnicity.

This suggests that the EGCG in green tea may benefit weight loss, but the amount needed for any benefit is not clearly understood. It should also be noted that just adding green tea to your diet won’t be enough to lose significant weight; food intake and exercise also need to be addressed.

2. Reduces Cholesterol Levels

Heart disease is the leading cause of death for men and women in the US. There is a strong need to lower the risks of heart disease. High blood cholesterol and triglyceride levels are important risk factors for heart disease.

The oxidation of low-density cholesterol (LDL) can cause plaque formation in the arteries, which is a risk factor for heart diseases and stroke. Green tea, by way of its antioxidant properties, prevents the oxidation of LDL.

Studies show that green tea consumption can reduce total blood cholesterol and bad cholesterol (LDL) levels.

3. Boosts Brain Health

Our brains require a healthy blood vessel system to function efficiently.

A study has corroborated the effect of green tea on the brain. Regularly drinking green tea has exhibited a positive impact on the activity of the working and memory areas of the brain.

Green tea contains bioactive compounds, including EGCG, that have been linked to a protective effect on neurons and a reduced risk of Alzheimer’s disease and Parkinson’s disease, the two most common neurodegenerative disorders.

A review suggests that the effect green tea on brain health is not just from one compound in green tea but from a combined influence of all components.

4. Brings a Dip in Blood Sugar Levels

Green tea has been shown to enhance insulin sensitivity in vitro and in human studies. Green tea consumption, as well as overall caffeine intake, is associated with a lowered risk of type 2 diabetes.

Long-term green tea intake was associated with lower fasting blood glucose levels in a study conducted on an elderly population in the Mediterranean islands.

Some studies show that daily consumption of green tea may help control type 2 diabetes. However, chronic green tea intake has also been shown to result in possible liver damage.

The way green tea impacts human health for diabetes risk still needs more research.

5. Promotes Oral Health

Green tea consumption is associated with improved dental health and a lower risk of cavities. The polyphenols, antioxidants, and natural fluoride content in green tea can effectively kill the bacteria that cause bad breath, tooth decay, cavities, and various gum diseases.

A study supported the antibacterial activity of green tea in the oral cavity in the reduction of the aforementioned oral afflictions. The antioxidant activity of green tea has also been linked to a reduced risk of oral cancer.

To reap the oral benefits of green tea, avoid adding sugar, honey, or other sweeteners to the tea.

6. Fights Against Aging

Green tea is well known for its antioxidant content, especially polyphenols. The antioxidant action of green tea may help protect the skin from the attack of harmful free radicals. Mice studies have shown green tea extract to possess antiwrinkle properties and delay collagen aging.

Additionally, the high levels of oligomeric proanthocyanidins in green tea are thought to help slow down premature aging if taken internally.

Topical application of green tea has been associated with prevention against damage caused by UV rays.

A 2006 study found that topical application and oral ingestion of green tea showed protection of skin cells from photoaging, but the amount was not considered significant.

7. Lowers Blood Pressure

Regular consumption of green tea is thought to help reduce the risk of high blood pressure. It helps keep blood pressure down by repressing angiotensin, a hormone that causes high blood pressure.

A study published in the Journal of Hypertension corroborated the effects of short-term green tea treatment in a hypertensive rat model. The study observed an improved cardiovascular function possibly because of the high antioxidant content in green tea.

8. Backents Hair Loss

Green tea is packed with antioxidants that help prevent hair loss and can also promote hair regrowth. The catechins in green tea help block DHT, which is the critical factor for hair loss, and the EGCG promotes hair growth by stimulating the hair cells.

In a study conducted on a group of experimental mice, the effects of green tea on hair growth were observed for 6 months. The researchers found that 33 percent of the mice in the experimental group, who received polyphenol extract in their drinking water, had significant hair regrowth whereas the mice in the control group, who had received regular water, showed no hair growth.

The amount of green tea needed to prevent hair loss is not clearly known. Start by consuming a few cups of green tea per day.

You may also rinse your wet hair with cool, freshly brewed green tea followed by a rinse with regular water after 10 minutes. Do this a few times a week for at least a few months. This may also help reduce problems such as dandruff and dry scalp.

9. Reduces the Risk of Cancer

Free radicals sneak into your system and wreak havoc on its normal physiology. Cancer is known to be caused by oxidative damage induced by free radicals. This damage can be curbed by antioxidants, reducing the risk of cancer.

The anticancer effects of the multiple antioxidants in green tea have been reported to lower the risk of various types of cancer, including breast, prostate, colorectal, pancreatic, esophageal, bladder, lung, and stomach cancers.

Drinking as many as 4 cups of green tea a day may provide antioxidants to fight cancerous growths. However, the exact amount of green tea needed to reduce cancer risks is not known, as there are many factors influencing such risks.

10. Maintains Bone Health

The high fluoride content in green tea helps maintain bone strength. Regular consumption of green tea is associated with a lower risk of fractures as a result of osteoporosis.

The antioxidant and anti-inflammatory properties of green tea have been associated with preventing a loss in bone density, suppressing bone fractures and accentuating the activity of bone cells.

Drink green tea every day to help preserve your bone density. Keeping in mind that green tea can lower the absorption of calcium, another bone-building nutrient, include calcium-rich foods and drinks in your diet.

Precautions and Risks with Green Tea

The popularity of green tea continues to grow worldwide. The indiscriminate usage of green tea is due to the enormous buzz about its health benefits.

Green tea is regarded as a safe and beneficial drink when consumed moderately, but some instances may warrant caution. The side effects related to overconsumption of green tea are as follows.

  • Green tea can cause an upset stomach and even constipation in some cases. Green tea extracts have been reportedly associated with liver and kidney problems in rare cases.
  • A typical cup of green tea can provide somewhere between 30 mg and 50 mg of caffeine. For most adults, up to 400 mg of caffeine is considered safe per day. Consuming excess amounts of green tea or in combination with other caffeine sources may result in adverse effects. However, keep in mind that caffeine sensitivity varies individually.
  • Oral supplements of green tea extract may be associated with liver damage in adults, especially in high doses. Green tea extract should be a strict no-no for children under 18 years of age as recommended by experts. Before taking any supplement, consult your doctor.
  • Pregnant or breastfeeding women may need to restrict their daily consumption of green tea. General recommendations for caffeine intake in pregnancy are 200 mg or less. Excess caffeine intake has been linked to an increased risk of miscarriage and birth defects associated with the deficiency of folic acid. In lactating women, caffeine is passed into their breast milk and can have direct implications on the nursing infant.
  • Excess intake of green tea may worsen symptoms associated with anxiety, anemia, diarrhea, and irritable bowel syndrome.
  • You may need to avoid drinking green tea if you have a bleeding disorder.
  • Supplements of green tea extract have been related to liver damage in rare cases and often aggravate an existing liver damage. Consult your doctor before you consider taking a green tea supplement. Keep a check on the symptoms of liver damage such as dark urine, yellowing of the skin, and abdominal pain.
  • Green tea reduces the absorption of calcium and iron. If you take calcium or iron supplements, do not consume green tea with them for optimal absorption.

Closing Note

The multiplicity of health benefits that green tea offers are overwhelming. Green tea houses scads of antioxidants, including catechins, that contribute to majority of its health benefits.

Weight management, blood sugar control, healthy skin, and even healthy brain functions are just some of the health benefits that are associated with green tea. To garner its benefits without succumbing to the side effects, green tea should be consumed in moderation and not considered as a magic cure for any health condition.

So, start your day with a cup of green tea to support good health.


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Published by
Holly Klamer, Registered Dietitian Nutritionist

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