Green Tea: Nine Proven Health Benefits

Medically Reviewed By Marie Lorraine Johnson MS, RD, CPT
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Green tea, which contains high levels of antioxidants, may have a positive impact on diverse areas of health, including mental wellness, protection against cancer, and weight management.  While all tea contains some amount of antioxidants, it is the way in which green tea is produced that boosts its nutrient profile. Unlike other teas, green tea is brewed from largely unprocessed, unfermented, unoxidized leaves, and it may contain higher amounts of antioxidants and other beneficial nutrients.

These health benefits have been popular in traditional medicine for thousands of years, with Chinese and Indian medicine using green tea to improve both physical and mental health. Experimental science is now increasingly investigating these impressive claims. 

Read on to learn the specific, science-backed benefits of green tea.

1. Protecting against cancer

there are green tea leaves on a wooden bowl
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A 2018 review of the impacts of green tea and its components has suggested some significant anticancer effects. 

Researchers evaluating in vitro, in vivo, and human studies taking place over the course of 30 years found evidence of positive effects in both animal and human cells. This included reduced cancer incidence in the general population, lower recurrence rates of cancer in stage 1 and 2 cancer patients, and tertiary cancer protection when paired alongside anticancer drugs.  

Researchers also found that habitual consumption of green tea over a 10-year period could lead to a delayed onset of cancer of up to 7.3 years later than those who drank less. 

However, more consistent evidence is required to definitively prove that green tea reduces the overall risk from all cancers and development stages. A 2020 database review of studies found that results were inconsistent in confirming the anticancer benefits of green tea. 

2. Promoting heart health

One 2019 review of epidemiological, experimental, and clinical studies suggests that tea consumption is associated with lower cardiovascular disease risks. 

The observed health effects of the consumption of tea compounds included protection against the development of cardiovascular disease. Regularly drinking green tea also demonstrated a decreased incidence of cardiovascular events and a lower risk of death from cardiovascular disease. 

3. Providing antioxidants

One significant component of green tea is a group of compounds called polyphenols, a powerful type of antioxidant that has been observed to benefit health with their neutralization of free radicals and anti-inflammatory properties.

Unbalanced levels of free radicals can lead to oxidative stress. This can be harmful over prolonged periods of time, potentially causing cell damage.  

Green tea is particularly high in these antioxidant polyphenol compounds, suggesting the potential for significant health impacts with its consumption. 

A 2020 collective review of both animal and human clinical applications of tea polyphenols across 104 studies supports the health benefits of green tea and its compounds. Researchers found that tea polyphenols do have significant antioxidative function, though they called for further studies.

4. Promoting skin health

A 2018 review shows the effects of green tea on skin health. Researchers were able to demonstrate the potential effects of topical tea polyphenols, with evidence of the repair of skin damage from UV rays as well as the prevention of associated skin cancers. 

In another review of human clinical trials, researchers similarly found evidence that both topical and ingested green tea treatments may function as a preventative tool against skin maturation processes and skin cancer. Additionally, research supported the efficacy of green tea-derived therapies in treating chronic, infectious, inflammatory, and hair disorders. 

However, it is noted that further investigation with larger patient numbers and more control for application is needed to verify the true efficacy of green tea treatments in most dermatological treatments. 

5. Boosting mood and mental function

A systematic database review found that green tea can positively influence:

  • anxiety
  • memory and attention
  • general brain function

6. Helping weight management

There has been an increasing amount of discussion on the effects of green tea on obesity and weight loss, with traditional medicine having claimed its weight reduction properties for years.  

In one 2014 review of animal and human clinical studies, researchers observed that green tea may be beneficial for the treatment and prevention of obesity.

However, this review also outlines an inconsistency of results, with efficacy being influenced by other factors such as the presence of caffeine in green tea supplements, patient hormone levels, diet and exercise factors, and genetic backgrounds. 

This inconsistency was also found by a 2014 review of meta-analyses and studies assessing participant weight loss related to green tea therapies. Researchers found that although there was a slightly higher rate of weight loss in the group supplementing with green tea, the difference was not enough to be statistically significant. 

7. Preventing type 2 diabetes

Some positive effects of green tea compounds on diabetes have been observed in animals. 

One review of both animal and human studies outlines the potential relationship between green tea consumption and the treatment of type 2 diabetes. Results showed a positive effect of green tea administration in rats, showing that the green tea component EGCG had significant intestinal effects and was also able to inhibit intestinal glucose uptake. 

The results for humans, however, were inconsistent with the findings for other animals and did not indicate such positive results against obesity and diabetes, potentially due to the difference in animal biofunctions. Researchers also noted that further human clinical trials should aim to develop alternative and safer treatment options against type 2 diabetes. 

8. Giving a longer life

In line with evidence that green tea may offer several positive health benefits, it has also been observed that drinking green tea may improve people’s overall length of life. 

One study reviewed two investigations including a total of over 115,000 participants from middle to old age, following up over a period of 14 years. It found that the consumption of green tea could lead to a reduced risk of all-cause mortality in all participants, particularly in those who had never smoked.  

9. Boosting gut health

In addition to other health benefits, research has also suggested that green tea can improve gut health. 

A review of studies found that the levels of polyphenols in green tea may promote the growth of beneficial species of gut bacteria while also preventing certain harmful bacteria from growing.

Preparing green tea

Tea preparation methods will vary according to the product. To yield the most beneficial green tea antioxidants, some research shows that brewing green tea at lower temperatures with a longer steeping time is ideal.

However, if a lengthy brewing time is not always practical, or if you prefer to avoid the bitter taste associated with a long brew, brewing your tea with freshly boiled water for just a few minutes can still extract the bioactive compounds. 

Summary 

Green tea comes with an extensive list of evidence outlining its potential health benefits. Positive health impacts may include heart health, cancer prevention, longer life, better skin and gut health, weight loss, and improved mental function. 

While more investigation is needed to definitively confirm some of these observations, particularly to establish efficacy and consumption amounts, green tea offers a powerful dose of antioxidants and is low in caffeine compared to other caffeinated drinks. 

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Medical Reviewer: Marie Lorraine Johnson MS, RD, CPT
Last Review Date: 2022 Feb 23
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THIS TOOL DOES NOT PROVIDE MEDICAL ADVICE. It is intended for informational purposes only. It is not a substitute for professional medical advice, diagnosis or treatment. Never ignore professional medical advice in seeking treatment because of something you have read on the site. If you think you may have a medical emergency, immediately call your doctor or dial 911.
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