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Green Tea: Uses, Benefits, Side Effects By Dr. Smita Barode  

By Dr Smita Barode +2 more

Introduction: 

Are you also a green tea lover? Did you know apart from weight management, green tea may have several other benefits? Tea is one of the most popular drinks globally consumed. It is often consumed as black, Oolong,and green tea as well as the popular Chai. Among these, green tea is known to have significant health benefits. Green tea is obtained from the plant Camillia Sinensis which belongs to the family Theaceae.  Green tea was brought to India from Japan in the 17th century. It is consumed mainly in Asia, the United States, Europe and North Africa. About 2.5 million tons of tea is produced worldwide, of which 20% is green tea. Freshly harvested tea leaves are steamed and prevented from getting fermented to produce green tea. This process preserves the polyphenols which may be responsible for the biological activity of green tea.1 Let us look at some benefits of drinking green tea. 

Nutritional Value of Green Tea: 

100 g of brewed green tea may contain the following nutrients: 

Green Tea Health Benefits

Nutritional Component Amount 
Water 99.93 g 
Energy 1 kcal 
Protein 0.22 g 
Zinc 0.01 mg 
Iron 0.02 mg 
Manganese 0.184 mg 
Copper 0.004 mg 
Vitamin C 0.3 mg 
Vitamin B1 0.007 mg 
Vitamin B2 0.058 mg 
Vitamin B3 0.03 mg 
Vitamin B6 0.005 mg 
Caffeine 12 mg 
Proanthocyanidin dimers 2.6 mg 

Table shows the nutritional value of green tea2 

Properties of Green Tea: 

Several studies have shown that green tea may have the following properties:1 

  • It may reduce the risk of cancer. 
  • It may be an antioxidant. 
  • It may act against microorganisms like bacteria and viruses.  
  • It may help improve heart health. 
  • It may help in case of arthritis. 
  • It may help reduce inflammation.  
  • It may lower bad cholesterol levels. 

Potential Uses of Green Tea for Overall Health 

There may be several benefits of having green tea. Some of the potential uses of green tea are: 

1. Potential use of green tea for the circulatory system 

A study by Naito et al. in 2009 showed that green tea might reduce the risk of circulatory diseases like atherosclerosis. Atherosclerosis may be caused when white blood cells adhere to the cells found in the inner lining of arteries and veins. This adherence of white blood cells may be caused by oxidised bad cholesterol (low-density lipoprotein). The catechins in green tea may inhibit the oxidation of bad cholesterol and thereby reduce the risk of atherosclerosis.3 However, more studies are required to confirm whether green tea is useful for atherosclerosis. Therefore, you must consult your doctor if you suspect any symptoms of heart disease. 

2. Potential use of green tea for cancer 

A study by Yang et al. in 2010 showed that green tea might help reduce the risk of cancer due to bioactive compounds like catechins. Green tea may affect some signaling pathways, which may inhibit the growth of cancerous cells and cause the death of cancerous cells. However, these studies were conducted on animal models. More studies are required to confirm if green tea may be beneficial against cancer.4 You must consult your doctor if you suspect cancer instead of self-medicating.  

3. Potential use of green tea for blood sugar levels 

A study by Park et al. in 2014 showed that drinking green tea may be beneficial for type 2 diabetes. Catechins present in green tea may inhibit glucose from entering the cells and reduce blood glucose levels.5 However, further studies on humans are required to check if green tea can reduce blood sugar. You must check your blood sugar levels regularly and consult your doctor in case of abnormalities. 

4. Potential use of green tea for bacterial infections 

A study by Reygaert et al. in 2018 showed that catechins in green tea might be beneficial against bacterial infections. Green tea catechins may bind to the cell membrane and damage it, leading to cell death. Green tea may act against bacteria like E. coli and pseudomonas.6 However, further studies are required to confirm if green tea may work for bacterial infections. You must immediately consult your doctor if you suspect bacterial infections. 

5. Potential use of green tea for weight management 

A study by Rothenberg et al. in 2018 showed that catechins in green tea might help reduce weight. Green tea catechins may inhibit digestive enzymes like pancreatic lipase, amylase and glucosidase. Therefore, there is a decrease in the absorption rates of sugar and fat. In addition, a reaction among microbes in the gut, residual carbohydrates and green tea catechins produce short-chain fatty acids, which may enhance fat metabolism. In these two ways, weight gain may be reduced.7 However, more studies are required to ensure these claims. You must consult your dietician before making changes in your diet. 

6. Potential use of green tea for inflammatory bowel disease 

Inflammatory bowel disease (IBD) is caused as a result of inflammation in the digestive tract. Diarrhea, abdominal pain, fatigue and reduced appetite are the main symptoms. According to a study by Barbalho et al. in 2019, catechins and polyphenols in green tea might be beneficial for IBD. Polyphenols may lower inflammation by stimulating the antioxidant enzymes and reducing inflammatory cytokines (inflammatory pathway mediators).8 However, more studies are required to check if green tea may be beneficial for inflammatory bowel disease. Therefore, you must consult your doctor if you have any symptoms of digestive disorders. 

7. Potential use of green tea for acne 

A study by Kim et al. in 2019 showed that oral intake and topical application of green tea extract might be beneficial for acne. The catechins present in green tea may possess anti-inflammatory and anti-microbial properties. Hence, green tea may reduce the inflammatory cytokines and act against the microbe P.acne, which is responsible for acne.9 However, further studies are required to check these findings. You must consult a skin specialist if you battle with acne. 

8. Potential use of green tea for fatty liver 

A study by Ghanaei et al. in 2018 showed that polyphenols in green tea might reduce ALT (alanine, transaminase) and AST (aspartate transaminase) concentrations. High concentrations of these liver marker enzymes may indicate liver damage. Additionally, green tea may lower the levels of bad cholesterol. In these ways, the risk of the fatty liver may be reduced.10 However, further studies on humans are yet to be done to check if green tea may improve liver function. Therefore, you must consult a doctor if you suspect any liver disease symptoms and take proper medications instead of self-medicating. 

Though studies show the benefits of green tea in various conditions, these are insufficient, and there is a need for further studies to establish the true extent of the benefits of green tea on human health. 

Catechins, which are organic antioxidants found in green tea, may be beneficial for dental health. By limiting the development of oral bacteria, these catechins help lower the risk of tooth decay, gum disease, and bad breath. Additionally, green tea may lessen gum inflammation and improve all aspects of dental health.

Dr. Siddharth Gupta, B.A.M.S, M.D (Ayu)

Also Read: Debunking The Myth: Does Green Tea Really Contain Caffeine?

How to Use Green Tea? 

You can consume green tea in the following way:  

First, boil some water, then add the tea leaves. You can brew the green tea leaves and steep them for a few minutes. Pour the green tea into a cup using a sieve and drink it hot. For more flavour, you can take flavoured green tea like cinnamon, ginger, lemon, mint, chamomile, etc. It is best to serve green tea plain without additives to get the maximum health benefits. You can add a dash of vanilla or cinnamon for a sweet flavour.11 

You must consult a qualified doctor before taking green tea in large quantities or any herbal supplements. Do not discontinue or replace an ongoing treatment of modern medicine with an ayurvedic/herbal preparation without consulting a qualified doctor 

Catechins and flavonoids, which are antioxidants found in green tea, may protect the eyes. According to some research, these substances may help lower the chance of developing common eye diseases like glaucoma and cataracts. The anti-inflammatory qualities of green tea may also be advantageous for overall eye health.

Dr. Rajeev Singh, BAMS

Side Effects of Green Tea 

Green tea side effects, according to a study by Bedrood et al. in 2017 are reported as follows:12 

  • Green tea may cause nervousness and anxiety. 
  • It may cause headaches. 
  • It may cause tremors. 
  • It may lower blood pressure. 
  • It may cause restlessness. 
  • It may cause insomnia. 
  • It may irritate the digestive tract. 

You must immediately consult your doctor if you experience any side effects after consuming green tea. 

Precautions to Take with Green Tea 

The following precautions must be taken before consuming green tea:13 

  • Pregnant and lactating women should be cautious while consuming green tea. 
  • People with liver diseases shall take adequate precautions before consuming green tea. 

It is advised to consult your doctor before consuming green tea if you have any pre-existing diseases. 

Interactions with Other Drugs: 

Green tea may show the following interactions: 

  • Green tea may interact with nadolol, a drug for high blood pressure and heart diseases.13 
  • Green tea may decrease the absorption of atropine, a drug used for diarrhoea.12 
  • Green tea may interact with warfarin, a drug used to prevent clots.12 

You must consult your doctor before consuming green tea if you are undergoing medical treatment. 

Also Read: Benefits of Matcha: A Closer Look at Its Research-Backed Health Advantages

Frequently Asked Questions: 

1) What are green tea benefits? 

Studies suggest that green tea is good for health. Green tea may improve heart and liver health. It may be useful for cancer, inflammatory bowel disease, diabetes, bacterial infections and acne. Additionally, green tea may help manage weight.3-10   

2) What are the nutrients in green tea? 

Green tea may contain carbohydrates and proteins. It may contain minerals like manganese, zinc, copper, etc. Additionally, green tea may contain vitamin B1, B2, B3 and B6, etc.2 

3) Is green tea good for the heart? 

Yes, green tea is good for the heart. It may reduce the risk of heart diseases like atherosclerosis due to the antioxidant properties of bioactive compounds like catechin.3   

4) What are the side effects of drinking green tea? 

Green tea in excess may cause nervousness, anxiety, headaches, tremors, restlessness, insomnia and irritation in the digestive tract. Additionally, it may abnormally lower blood pressure.12   

5) Are there any green tea liver benefits? 

Yes, green tea may be beneficial for the liver. Polyphenols in green tea might reduce ALT and AST concentrations and lower bad cholesterol levels, thereby improving liver health.10 

References: 

  1. Chacko SM, Thambi PT, Kuttan R, Nishigaki I. Beneficial effects of green tea: a literature review. Chinese medicine. 2010 Dec;5(1):1-9. Available from: https://cmjournal.biomedcentral.com/articles/10.1186/1749-8546-5-13  
  1.  Beverages, tea, green, brewed, regular [Internet]. Food Data Central. [cited 2022 Nov19]. Available from:  https://web.archive.org/web/20170707194019/https://ndb.nal.usda.gov/ndb/foods/show/4329?fgcd=&man=&lfacet=&count=&max=&sort=&qlookup=&offset=&format=Full&new=&measureby= 
  1. Naito Y, Yoshikawa T. Green tea and heart health. Journal of cardiovascular pharmacology. 2009 Nov 1;54(5):385-90. Available from: https://journals.lww.com/cardiovascularpharm/fulltext/2009/11000/green_tea_and_heart_health.5.aspx 
  1. Yang CS, Wang X. Green tea and cancer prevention. Nutrition and cancer. 2010 Sep 23;62(7):931-7. Available from: https://www.tandfonline.com/doi/pdf/10.1080/01635581.2010.509536 
  1. Park JH, Bae JH, Im SS, Song DK. Green tea and type 2 diabetes. Integrative Medicine Research. 2014 Mar 1;3(1):4-10. Available from: https://www.sciencedirect.com/science/article/pii/S221342201300098X 
  1. Reygaert WC. Green tea catechins: Their use in treating and preventing infectious diseases. BioMed research international. 2018 Jul 17;2018. Available from: https://www.hindawi.com/journals/BMRI/2018/9105261/ 
  1. Rothenberg DO, Zhou C, Zhang L. A review on the weight-loss effects of oxidized tea polyphenols. Molecules. 2018 May 14;23(5):1176. Available from: https://www.mdpi.com/1420-3049/23/5/1176/pdf 
  1. Barbalho SM, Bosso H, Salzedas-Pescinini LM, de Alvares Goulart R. Green tea: A possibility in the therapeutic approach of inflammatory bowel diseases?: Green tea and inflammatory bowel diseases. Complementary Therapies in Medicine. 2019 Apr 1;43:148-53. Available from: https://www.sciencedirect.com/science/article/pii/S0965229918311555 
  1. Kim S, Park TH, Kim WI, Park S, Kim JH, Cho MK. The effects of green tea on acne vulgaris: A systematic review and meta‐analysis of randomized clinical trials. Phytotherapy Research. 2021 Jan;35(1):374-83. Available from: https://onlinelibrary.wiley.com/doi/abs/10.1002/ptr.6809 
  1. Mansour‐Ghanaei F, Hadi A, Pourmasoumi M, Joukar F, Golpour S, Najafgholizadeh A. Green tea as a safe alternative approach for nonalcoholic fatty liver treatment: A systematic review and meta‐analysis of clinical trials. Phytotherapy research. 2018 Oct;32(10):1876-84. Available from: https://onlinelibrary.wiley.com/doi/abs/10.1002/ptr.6130 
  1. Tea [Internet]. The Nutrition Source. 2022 [cited 2022Nov20]. Available from: https://www.hsph.harvard.edu/nutritionsource/food-features/tea/ 
  1. Bedrood Z, Rameshrad M, Hosseinzadeh H. Toxicological effects of Camellia sinensis (green tea): A review. Phytotherapy Research. 2018 Jul;32(7):1163-80. Available from: https://onlinelibrary.wiley.com/doi/abs/10.1002/ptr.6063 
  1. Green tea [Internet]. National Center for Complementary and Integrative Health. U.S. Department of Health and Human Services; [cited 2022Nov19]. Available from: https://www.nccih.nih.gov/health/green-tea 

Disclaimer: The information provided here is for educational/awareness purposes only and is not intended to be a substitute for medical treatment by a healthcare professional and should not be relied upon to diagnose or treat any medical condition. The reader should consult a registered medical practitioner to determine the appropriateness of the information and before consuming any medication. PharmEasy does not provide any guarantee or warranty (express or implied) regarding the accuracy, adequacy, completeness, legality, reliability or usefulness of the information; and disclaims any liability arising thereof.

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