Health Benefits of Green Tea

List of Green Tea Beneficial Effects:

• 1. Longevity
• 2. Improved memory and learning
• 3. Fat-burning and anti-obesity
• 4. Skin protection from UV
• 5. Cholesterol lowering
• 6. Reduced risk of diabetes
• 7. Heart protection
• 8. Blood pressure lowering
• 9. Reduced risk of stroke
• 10. Reduced risk of Alzheimer's and Parkinson's diseases
• 11. Prevention of atherosclerosis
• 12. Antithrombotic effect
• 13. Better exercise endurance
• 14. Reduced smoking harms
• 15. Osteoporosis prevention
• 16. Tooth decay prevention
• 17. Anti-inflammatory properties
• 18. Antimicrobial effects
• 19. Liver protection
• 20. Gastrointestinal benefits

by eMedExpert staff
Medical references reviewed: August, 2018

What is green tea good for? Numerous modern studies have researched the useful properties of green tea. And today scientists continue to investigate known properties and discover new health benefits of green tea.

Tea contains polyphenols which are strong antioxidants and possess numerous biochemical activities. Tea polyphenols consist mostly of catechins, the most powerful of them is epigallocatechin gallate (EGCG). EGCG is found only in green tea. Since ancient times green tea has been considered a health-promoting beverage and currently researchers find more convincing proof of its healing qualities.

Based on the growing number of studies that explore health benefits of green tea, I made this article describing clear beneficial effects you can get with regular drinking.

1 Longevity

Green tea may protect against death from all causes, especially cardiovascular disease. The findings from numerous Japanese studies might explain in part the reason why the people in Japan live longer than people in any other country.

What research says:

• Green tea may reduce the risk of mortality from cardiovascular disease[44], cerebrovascular disease, and respiratory disease[38].
• People drinking 5 or more cups a day have a significantly lower risk of death from all causes, especially lower risk of dying from cardiovascular disease and stroke[1].

Green tea properties contributing to lifespan extension:

• Antioxidant [42]
• Anti-inflammatory[41]
• Immunomodulatory[43]
• Anti-mutagenic[39]. Green tea polyphenols affect carcinogen metabolism, DNA adduct formation, the interaction of ultimate carcinogen or the scavenging of free radicals[40].

2 Memory and Learning

One of the important health benefits of regular green tea drinking is improved memory and learning ability.

What research says:

• High green tea drinking maintains cognitive function[2]
• Green tea consumption may enhance learning and memory ability[3].
• Green tea enhances functional brain connectivity[36].
• EGCG enhances hippocampal neurogenesis in adults[46].

Underlying mechanism:
The main components of green tea that are thought to work on improving brain function and neuroprotection are polyphenols, epigallochatechin-3-gallate (EGCG), a very potent antioxidant. High use of oxygen during the metabolic processes leads to generation of a large number of free radicals (highly reactive molecules). EGCG can decrease oxidative damage to DNA and suppress brain dysfunction[45].

3 Weight control

There is strong scientific evidence that green tea has fat-burning and antiobesity properties.

What research says:

• Drinking 4 cups of green tea daily promotes a significant weight loss and reduction of systolic blood pressure[47].
• Green tea extract rich in catechins promotes reduction in body fat, total and LDL cholesterol[35], that in its turn contributes to a decrease in obesity and cardiovascular disease risks.

Underlying mechanism:
Green tea polyphenols are known to increase the metabolism of fats by the liver (thermogenic effect), inhibit lipase (fat absorption enzyme) in the digestive tract, and provide a feeling of satiety and fullness[4]. Green tea can reduce body weight in obese persons by increasing energy expenditure and fat oxidation[5].

4 Skin protection from Ultraviolet

Green tea polyphenols protect the skin from the damage caused by ultraviolet radiation such as UV-induced sunburn, UV-induced immunosuppression and photoaging of the skin.

Underlying mechanism:
Green tea exerts photoprotection by various cellular, molecular and biochemical mechanisms[6]. Green tea polyphenols prevent UV-induced immunosuppression by repair of DNA damage and enhancement of nucleotide excision repair genes[48]. Also, green tea polyphenols protect the skin by improving the elastic tissues[7].

5 Lowering cholesterol

Green tea lowers total cholesterol and LDL cholesterol levels and improves the ratio of HDL to LDL cholesterol.

What research says:

• People who drink green tea daily have lower cholesterol levels than those who do not drink it [8].

Underlying mechanism:
One of the underlying mechanisms by which green tea lowers blood cholesterol levels is by reducing lipids absorption in the digestive tract and promoting their excretion from the body[9].

6 Diabetes and blood glucose levels

Green tea may help regulate the blood sugar and reduce the risk for type 2 diabetes.

What research says:

• People who drink more than 6 cups per day are less likely to develop diabetes than those who drink less than 1 cup per week[10].
• Daily use of green tea has favorable effect on insulin resistance [49].

Underlying mechanism:
Green tea antidiabetic properties may be partly explained by its caffeine content.

Japanese researchers[11] demonstrated that daily intake of green tea extract lowered the hemoglobin A1c level in people with borderline diabetes, that indicates the increased body's ability to utilize blood sugar. Hemoglobin A1c is a test that measures the amount of glycosylated hemoglobin molecules in red blood cells. These molecules attach to glucose and so people have more of them if they have more glucose in the blood.

7 Heart protection: Asian paradox

Green tea may protect against heart disease. Green tea consumption might explain the "Asian paradox" - when people living in Asian countries smoke cigarettes heavily, but have relatively low incidence of heart disease.

What research says:

• The more green tea people drink, the less likely they are to have coronary artery disease[12]
• Green tea can reduce heart muscle cells death after a heart attack (myocardial infarction)[13]. Also, EGCG appears to speed up the recovery of heart cells.

Underlying cardioprotective mechanisms of green tea:

• Vasculoprotective
• Antioxidative
• Antithrombogenic
• Anti-inflammatory
• Cholesterol-lowering

8 Anti-hypertensive

Green tea lowers blood pressure and helps prevent hypertension.

What research says:

• Among persons consuming tea regularly for at least one year, the risk of developing high blood pressure was 46% lower among those who drank 1/2 cup to 2 1/2 cups per day, and 65% less among those consuming more than 2 1/2 cups per day[15].

Underlying mechanism:
Tea increases body's production of nitric oxide, which dilates arteries and thereby reduces blood pressure[14].

9 Stroke

Green tea shows promise in the prevention of stroke[1, 16]. Furthermore, the green tea polyphenols, particularly EGCG, have been shown to protect brain cells from destructive processes following stroke[17].

10 Alzheimer's and Parkinson's diseases

Green tea may reduce the risk of degenerative disorders of the central nervous system, such as cognitive decline, Alzheimer's and Parkinson's diseases.

What research says:

• People who consume more than 2 cups of green tea a day may have a 50% lower chance of developing cognitive impairment, than those who drink fewer than 2 cups a day, or who consume other tested beverages[19].
• Green tea improves cognitive function in patients with Alzheimer's disease[50].

Underlying neuroprotective mechanism:
Green tea catechin polyphenols produce several neuroprotective (i.e. lessening the damage to brain cells) activities like iron chelation, scavenging of radicals, activation of survival genes and cell signaling pathways, and inhibitory action on Abeta fibrils/oligomers formation[18, 20].

11 Atherosclerosis

Regular green tea drinking may be beneficial for the prevention of atherosclerosis, when the plaque builds up on the insides of the arteries [21].

Underlying mechanism:
Green tea effectively reduces the risk of atherosclerosis by lowering LDL cholesterol, triglycerides, lipid peroxides (free radicals that damage LDL cholesterol and other lipids) and fibrinogen (a protein in the blood involved in the formation of blood clots), and by reversing endothelial dysfunction. Green tea is a powerful antioxidant and protects LDL cholesterol from oxidation[22]. Oxidized cholesterol gets sticky and tends to cling to the walls of the arteries, leading to the development of atherosclerosis.

12 Anticlotting effect

Green tea appears to prevent the formation of blood clots (thrombosis). Green tea catechins produce potent antithrombotic effect by inhibition of platelet aggregation (blood clot formation)[23].

13 Increased exercise endurance

Animal studies indicate that green tea increases exercise endurance. Green tea catechins stimulate fatty acid utilization and improve metabolic capacity during intensive physical activity [24].

14 Smoking harms

Regular green tea drinking may protect smokers from oxidative damages and reduce cancer risk or other diseases caused by free radicals generated by cigarette smoking (e.g. cardiovascular diseases, atherosclerosis, asthma) [25]. Green tea may prevent future cardiovascular disorders in chronic smokers[26].

15 Bones

Green tea may prevent osteoporosis and bone loss.

What research says:

• Green tea may increase bone mineral density[27].
• Bone mineral density is 2.8% higher in people who drink green tea than in those who do not drink tea [28]. Over the 4 years period, tea drinkers lost an average of two times less of their total hip bone mineral density, than non-tea drinkers.

16 Tooth decay (dental caries)

Green tea prevents tooth decay. It kills the bacteria that cause dental plaques and halitosis (bad breath) and increases the acid resistance of tooth enamel [29].

17 Arthritis

Green tea reduces inflammation and slows cartilage destruction in people with arthritis [30]. Recently green tea was found to exert anti-rheumatic activity in rheumatoid arthritis due to EGCG anti-inflammatory properties [37].

18 Antimicrobial activity

Green tea catechins have anti-bacterial, anti-viral and anti-fungal activities[31].

What research says:

• A component of green tea may be useful in treating severe sepsis, an abnormal immune system response to bacteria[32].
• Green tea extract significantly inhibits the growth of many pathogens, including Staphylococcus aureus, Escherichia coli, Salmonella, Listeria monocytogenes, and food-poisoning bacteria Bacillus cereus[51].

19 Liver protection

Green tea appears to support healthy liver and protect it from the damage by toxic substances such as alcohol. Men who drink more than 10 cups of green tea per day are less likely to develop disorders of the liver[33].

20 Gastrointestinal tract

Green tea activates intracellular antioxidants, suppresses formation of procarcinogens, and reduces inflammation in the gastrointestinal tract.

Drinking more than 10 cups per day may prevent chronic atrophic gastritis[34]. Also, it may help reduce inflammation associated with Crohn's disease and ulcerative colitis.

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Published: 2009
Last updated: July 04, 2018