Green Tea: 10 Incredible Science-Backed Health Benefits

Green tea has become a popular beverage these days, the second most consumed beverage in the world, after water, according to the  International Institute of Sustainable Development (1).


What accounts for its popularity? Certainly, green tea is a delicious and refreshing beverage. But it’s equally revered for its health-promoting properties. After all, according to studies, green tea use may improve skin health, aid in weight loss, reduce the risk of cardiovascular disease, and much more. 


This article covers everything you need to know about green tea, including its history and science-backed health benefits. 


History of Green Tea


The origin of green tea dates back to 2737 B.C. in China. The discovery was made by accident when Chinese Emperor Shennong drank a dead tea leaf with water. He found the taste to be refreshing, and thus a new beverage was created. Unfortunately, the elite were the only Chinese social strata that could afford green tea. Only in the 14th century did green tea become widely available for consumption and medical uses.


In the 19th century, European explorers brought the wildly popular green tea to the West. Due to its incredible flavor, it became the national beverage of the United Kingdom alongside black tea. Soon after, English colonists journeyed abroad and introduced America to the delicious taste of green tea. 


The tea became so popular among the colonists in 1767 that Parliament levied a Tea Tax due to its popularity. Indeed, the famous Boston Tea Party occurred because the colonists were quite angry. Consequently, 45 tons of expensive green tea were dumped into the port.


The Boston Tea Party may have been the peak of green tea's historical significance. Still, subsequent green tea history has been marked by a continuous increase in the beverage's popularity and health advantages. In the past few decades, numerous studies have been conducted to identify the health benefits that green tea's high antioxidant content delivers to its consumers. The more scientists discover, the more they are impressed by green teas like 8th Wonder’s Sparkling Green Tea. 

How is Green Tea Made?


Green tea is the most natural form of tea. In fact, for centuries, green tea was the only tea available. You see, with the exception of herbal tea, all teas are brewed from the dried leaves of the Camellia sinensis bush. Tea varieties are determined by the degree of leaf oxidation. Green tea is produced by steaming, pan-frying, and drying the plant leaves.


Green tea is manufactured from leaves that have not been oxidized and are, therefore, one of the least processed tea varieties. This is why it contains the highest levels of antioxidants and beneficial polyphenols that help provide all those health benefits you’ve probably heard about. This is also why 8th Wonder developed its own health-promoting blend of superfoods to include in its Organic Sparkling Green Tea. 


Health-Promoting Compounds in Green Tea


Green tea is a rich source of bioactive compounds that have been shown to provide numerous health benefits (2).


Tea is abundant in polyphenols, which are natural substances with health advantages, including anti-inflammatory and anti-cancer properties.


The catechin epigallocatechin-3-gallate is present in green tea (EGCG). Catechins are natural antioxidants that aid in preventing cell damage and provide additional advantages. These compounds can inhibit the generation of free radicals in the body, thus protecting cells and molecules from deterioration. Why is this important? Free radicals contribute to aging and other illnesses, so inhibiting their generation is essential to disease prevention. 


Among the most potent chemicals in green tea is EGCG. Researchers have examined its potential to aid in the treatment of a variety of illnesses. It is one of the primary components responsible for green tea's therapeutic benefits (3).


Nutrients in Green Tea


Unlike those sugary, chemical-laced beverages, green tea packs a nutritional punch. In addition to the potent bioactive compounds covered above, green tea also includes:


  • Theanine, an amino acid that boosts levels of the relaxing neurotransmitter gamma amino butyric acid in the brain.

  • Fluoride, a natural mineral that helps strengthen tooth enamel.

  • Vitamin C, an essential nutrient that enhances immunity. It also has an anti-aging effect, as it helps tighten and rejuvenate the skin. 

  • Potassium, a crucial mineral and electrolyte that helps rid the body of waste products and regulates blood pressure. 

  • Caffeine, a stimulant that increases energy and alertness.

Health Benefits of Green Tea


Green tea has been used for medicinal purposes in China and Japan for thousands of years. Studies in the last few decades have shown what ancient medicine men long knew – green is beneficial for your health.


Below are ten of the most common science-backed health benefits of green tea.


May Help Prevent Cancer


In countries with high consumption of green tea, some cancer rates tend to be lower. However, investigations on humans have not consistently demonstrated that green tea consumption reduces the risk of cancer.


However, animal and test tube cell studies suggest that green tea consumption may be beneficial for specific types of cancer, including (4):


  • Prostate
  • Lung
  • Bladder 
  • Skin
  • Colorectal
  • Esophageal
  • Stomach
  • Breast
  • Ovarian

In addition, green tea polyphenol extracts used topically may shield the skin from UVB rays. A 2018 review of in vitro, in vivo, and human trials indicated the potential chemopreventive value of tea polyphenols for UVB-induced skin cancer (5).


May Boost Brain Function


Numerous studies suggest green tea may improve focus, concentration, and alertness. But, of course, the primary active ingredient for mental acuity is the well-known natural stimulant caffeine.


Green tea has less caffeine than coffee, yet enough to elicit a response without creating the jittery side effects of consuming too much caffeine.


How does the caffeine in green tea boost brain function?


Caffeine affects the brain by blocking a neurotransmitter called adenosine, which is an inhibitory neurotransmitter. In this way, it makes neurons fire more often and increases the number of neurotransmitters like dopamine and norepinephrine (6, 7)


Multiple studies have demonstrated that caffeine can enhance various elements of brain function, including mood, alertness, reaction time, and memory (8).

In addition, green tea contains another potent brain booster, L-theanine, an amino acid  that can cross the blood-brain barrier.  L-theanine enhances the inhibitory neurotransmitter GABA's activity, which provides anti-anxiety properties. It also boosts dopamine and alpha wave generation in the brain (9, 10).


Caffeine and L-theanine may have synergistic effects, according to studies. This indicates that combining the two can significantly enhance brain function (11, 12).


In addition, green tea may help enhance memory, thanks partly to its L-theanine content. Case in point: A 2014 study of 12 healthy volunteers published in the journal Psychopharmacology discovered that green tea extract enhanced the individuals' working memory, a form of short-term memory crucial for organizing, comprehending, reasoning, and problem-solving (12a).


For this study, patients received either 27.5 mg of green tea extract or a placebo in a milk-based beverage. The participants subsequently performed specific tasks while an MRI monitored their brain activity. Those that consumed the green tea extract exhibited enhanced brain connectivity, or the degree to which various regions of the brain communicate with one another, as well as enhanced working memory and task performance.


May Help You Lose Weight 


According to an analysis of multiple research studies, the catechins in green tea and caffeine may play a role in boosting energy metabolism leading to weight loss (13).


Another meta-analysis of several research studies revealed that  the catechins and caffeine in green tea generated weight loss benefits synergistically, as opposed to being the product of caffeine alone (14)


But what about its fat-burning potential? In a trial involving 10 healthy males, the use of green tea extract boosted caloric expenditure by 4%. In a second study with 12 healthy males, green tea extract boosted fat oxidation by 17% compared to placebo (15, 16).


Remember that most studies showing weight-loss effects used green tea extract with significantly high levels of catechins. Consequently, drinking a daily cup of green tea may show different fat-burning results. 


May Have an Anti-Aging Effect On The Brain 


Not only can green tea support proper brain function in general, but it may also protect the brain of older persons. 


After all, the risk of cognitive impairment increases with age. For example, an estimated 5.4 million people in the United States may have Alzheimer's disease, the most common cause of dementia in the older adult population. (17, 18). Indeed, a whopping one in ten Americans over the age of 65 has Alzheimer’s (19).


Another typical neurodegenerative illness in older adults is Parkinson's disease, which results in the loss of dopamine-producing brain neurons.


Fortunately, green tea may help. Numerous studies on animal models and in test tubes suggest that green tea might exert a protective effect on neurons in the brain, potentially reducing dementia risk (20, 21, 22).

May Improve Heart Health


There is also scientific evidence that green tea consumption may protect the heart and cardiovascular system. 


For example, a 2006 study revealed that consuming green tea is connected with a lower risk of cardiovascular disease-related mortality. The study tracked approximately 40,000 Japanese volunteers aged 40 to 79 for eleven years, beginning in 1994. Participants who consumed at least five cups of green tea per day had a lower risk of cardiovascular disease-related mortality (23).


These results were corroborated by a 2016 meta-analysis of studies on green tea and cardiovascular disease. The analysis covered a total of nine studies with 259,267 participants. 

The study's authors determined that drinking green tea reduced the risk of cardiovascular and ischemic disorders (24).


Finally, the polyphenols in green tea may reduce blood pressure, reduce inflammation, and enhance epithelial function, thereby reducing the risk of heart disease in obese or overweight individuals, according to reviews published in 2017 and 2019 (25, 26).


May Reduce Your Risk of Type 2 Diabetes


Type 2 diabetes has become a public health crisis worldwide, especially in the United States. An estimated one in ten Americans is presently afflicted by this disease (27). 


Elevated blood sugar levels are a symptom of type 2 diabetes, which may be brought on by insulin resistance or an inability to make insulin.


Studies indicate that green tea may increase insulin sensitivity and decrease glucose levels, potentially reducing the risk of type 2 diabetes (28). For example, a Japanese study found that people who consumed the most green tea had a 42% decreased risk of developing type 2 diabetes (29).


In addition, according to a meta-analysis of 7 studies with a total of 286,701 participants, tea drinkers had an 18% decreased chance of developing diabetes (30).


May Help Reduce Rheumatoid Arthritis


Rheumatoid arthritis is a chronic inflammatory autoimmune condition primarily affecting the joints, leading to pain and swelling of the joints. However, it can also affect other bodily systems, including the eyes, heart, skin, lungs, and blood vessels.

 

It is believed that between 1.3 and 1.5 million people in the United States have rheumatoid arthritis, also known as RA. Fortunately, green tea consumption may be able to help ease their symptoms.


In a study published in The Journal of Nutrition, rats administered green tea extract in their drinking water and subsequently induced with the autoimmune disease rheumatoid arthritis (RA) exhibited fewer severe symptoms than rats with RA drinking plain water (31). There is a need for additional research on humans, but the researchers believe that green tea extract may be beneficial when combined with traditional RA treatment.


Research published in a 2011 review in Arthritis Research & Therapy reveals a comparable anti-inflammatory impact in rats with osteoarthritis. Still, it's too early to say whether the same results would be observed in humans (32).


May Reduce Blood Pressure


High blood pressure is a primary cause of cardiovascular disease. Here, again, green tea may help this condition. For example, a 2020 study of 1,697 people published in the Journal Medicine found that drinking green tea significantly lowered blood pressure, especially in those with high blood pressure (33).


The same 2020 study mentioned above suggests that green tea's potential to decrease blood pressure may be linked to its high antioxidant content. These antioxidants lessen inflammation and widen blood vessels, allowing easier blood circulation. 

May Help Prevent Stroke


According to the CDC, stroke is the top cause of death and disability among people in the United States. Fortunately, the consumption of green tea may help reduce the risk of stroke (34).


In a 2020 study published in the American Journal of Clinical Nutrition, the tea-drinking habits of approximately 500,000 Chinese adults were examined. It was shown that drinking tea, mainly green tea, was connected with a decreased risk of stroke. Furthermore, the more green tea consumed, the lower a person's risk of stroke (35).

May Increase Life Span


According to 2020 research published in the European Journal of Preventive Cardiology, consuming tea, notably green tea, is associated with a longer and healthier life (36). 


The study monitored 100,902 Chinese individuals who had no prior history of a heart attack, stroke, or cancer for more than seven years. The researchers placed the participants into one of two groups: those who consumed tea three or more times per week and those who drank tea less than three times per week.


The results? Those who drank tea three or more times a week had a lower risk of mortality from all causes than those who did not regularly consume tea. They were also less likely to acquire the atherosclerotic cardiovascular disease, characterized by plaque buildup in blood vessels. Atherosclerosis significantly increases the risk of heart attack or stroke. 


In addition, green tea specifically was associated with a reduced risk of death from all causes except for coronary heart disease. Scientists attribute this to the antioxidants included in green tea, which help prevent cell damage and disease.


Types and Forms of Green Tea


Green tea is a versatile beverage available in many types and forms, including:


  • Bottled and sweetened with sugar or an artificial sweetener. 8th Wonder’s Sparkling Green Tea is a delicious, health-promoting choice, as it also contains passionfruit, ginseng, and other superfoods.
  • Individual tea bags
  • Loose leaf
  • Instant powder
  • Green tea supplements, in capsules or liquid extracts

Side Effects

Green tea is safely tolerated by most people. Therefore, there are minimal documented adverse effects linked to drinking this beverage.


However, it is essential that you are aware of the following potential health risks and complications:


Sensitivity to caffeine: People with significant sensitivity to caffeine may feel insomnia, anxiety, irritability, nausea, and stomach discomfort after consuming green tea.


Liver problems: In rare instances, consuming a high quantity of green tea extract may adversely affect liver function.


Combining green tea consumption with other stimulants: If a person takes green tea in conjunction with stimulant medicines, their blood pressure and heart rate may rise, which may increase the risk of a heart attack.


It’s always wise to consult a physician before beginning any herb or supplement regimen.

A Brief Review

Green tea is a mainstay in many cultures and may provide significant science-backed health benefits, such as supporting the brain and heart and increasing longevity. However, those on specific drugs or with a caffeine sensitivity may be susceptible to health hazards.

If you don't currently drink green tea and are unsure if it's healthy for you, consult a dietitian or healthcare professional for advice on how it may affect your unique health objectives.


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References

1- https://www.iisd.org/publications/report/global-market-report-tea

2- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2855614/

3- https://pubmed.ncbi.nlm.nih.gov/28864169/

4- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4997428/

5- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5774988/

6- https://pubmed.ncbi.nlm.nih.gov/1356551/

7- https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1600-0773.1995.tb00111.x

8- https://onlinelibrary.wiley.com/doi/full/10.1111/j.1467-3010.2007.00665.x

9- https://pubmed.ncbi.nlm.nih.gov/17182482/

10- https://pubmed.ncbi.nlm.nih.gov/17928735/

11- https://academic.oup.com/jn/article/138/8/1572S/4750819

12- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4480845/

12a- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4159594/

13- https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD008650.pub2/full

14- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6099746/

15- https://academic.oup.com/ajcn/article/70/6/1040/4729179

16- https://academic.oup.com/ajcn/article/87/3/778/4633440

17- https://www.alzra.org/blog/faqs/how-many-people-in-the-united-states-have-alzheimers-disease/

18- https://www.nia.nih.gov/health/what-alzheimers-disease

19- https://www.alzheimers.net/alzheimers-statistics

20- https://pubmed.ncbi.nlm.nih.gov/15350981/

21- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6493995/

22- https://pubmed.ncbi.nlm.nih.gov/26092629/

23- https://jamanetwork.com/journals/jama/fullarticle/203337

24- https://www.internationaljournalofcardiology.com/article/S0167-5273(15)00025-X/fulltext

25- https://pubmed.ncbi.nlm.nih.gov/28215148/

26- https://pubmed.ncbi.nlm.nih.gov/31817990/

27- https://www.cdc.gov/diabetes/basics/type2.html

28- https://academic.oup.com/ajcn/article/98/2/340/4577179

29- https://pubmed.ncbi.nlm.nih.gov/16618952/

30- https://jamanetwork.com/journals/jamainternalmedicine/fullarticle/773949

31- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2693422/

32- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3239363/

33- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7015560/

34- https://www.cdc.gov/chronicdisease/resources/publications/factsheets/heart-disease-stroke.htm

35- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7223259/

36- https://academic.oup.com/eurjpc/article/27/18/1956/6125502?login=false