Green Tea Benefits

Green tea has been known for its curative properties for centuries in China and is now being widely consumed all over the world. The main benefit from green tea is derived from the substance known as polyphenol. The most active type of polyphenol (also referred to as catechins) is the epi-gallo-catechin gallate (EGCG). A cup of green tea (2.5 g of green tea leaves/200 mL of water) may contain 90 mg of EGCG.  EGCG has a wide range of action on the functioning of human body and has been found to be beneficial in many disorders that affect the body ranging from simple infections to deadly cancers. Additionally, green tea also contains proteins, vitamins, minerals and other trace elements in varying quantities that accentuates the benefits of the polyphenols.

 

Green tea is considered as the fourth commonest dietary supplement being used in the US.¹ Green Tea also refreshes the mind and body by enhancing wakefulness, facilitating the formation of better ideas, decreasing tiredness and relaxing the muscles.²

 

The most evident effect of green tea is its antioxidant activity. Our body uses oxygen at higher concentration to destroy old cells and infectious organisms. This process is commonly referred to as oxidation. During this process, certain specialised molecules known as free radicals, are released to aid in the process of oxidation. At times, the amount of free radicals is abnormally high resulting in the destruction of healthy cells and tissues also. To combat this, the body generally stores certain antioxidant molecules that neutralise the effect of the free radicals. However, our body needs additional antioxidants in the form of supplements to function more effectively against the free radicals. The EGCG in green tea is a potent antioxidant that helps the body to overcome the effects of these free radicals across various cells and tissues in the body.^3-5

 

Some Basics about Different Types of Teas

According to some Chinese legends,  the tea plant was discovered by the Chinese emperor Shen-Nung when leaves from a wild bush accidently felt into a pot of boiling water. This was almost 50 centuries ago and now tea consumption has become widely popular all over the world. Tea consumption is so popular that it has been rated as the second most commonly consumed beverage next to water.⁶ 

The tea plant (generic name: Camellia sinensis) grows well in warm climates. It has been believed that tea plants growing in high altitudes are the sources of best tea leaves. The smallest and youngest leaf and bud of the tea plant are picked to prepare tea. These leaves undergo certain processes before being available to you in different forms.

Based on the brewing and processing methods followed the types of tea have been categorised as:

• Unfermented or green tea
• Semi-fermented or oolong tea
• Fermented or black tea ^2,7

 

The tea leaves are steamed, fermented and dried before being marketed for use. This process alters the composition of the tea leaves that are supposed to contain almost 4000 different types of chemicals.

 

Why Green Tea is Unique

The process of fermentation followed in the manufacture of black tea and oolong tea converts the polyphenol compounds into a different form which is not beneficial. Green tea retains the polyphenolic compounds as it is not fermented. EGCG found in good quantities in green tea is a potent antioxidant and also has various other properties. The benefits of green tea consumption were initially introduced by the Chinese. The traditional Chinese medicine recommends green tea for numerous ailments such as headaches, body aches, pains, indigestion, and depression. It has also been advised as detoxifier, energizer and, in general, to prolong life.
Along with EGCG, green tea also contains proteins, amino acids, carbohydrates, vitamins B, C, and E, caffeine and theophylline, and minerals and other trace elements in varying quantities. ^{7, 8} 

 

Green Tea Benefits for the Heart

The normal functioning of our heart is mediated by a number of factors. Although the heart can function quite well in most of the instances, repeated stress causing factors can alter the functioning leading to numerous heart related conditions.

 

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Anti-thrombogenic Effect

A common cause of blocks in the blood vessels of the heart is the formation of thrombus (a collection of different kinds of cells and tissues). The collection of fat cells is one of the major factors in formation of the thrombus. Excess fat in the body tends to collect on the walls of the blood vessels resulting in narrowing of the blood vessels. The process of thrombus formation is further accentuated by the accumulation of certain special cells known as platelets. These platelets normally help in clotting of the blood in case of injuries and are protective blood cells. However, in case of thrombus formation, their action is considered injurious. resulting in a possible heart stroke. The EGCG in green tea prevents these effects on the blood vessels of the heart and helps them to supply enough blood to the muscles of the heart. ^{3, 6-11} 

 

Anti-inflammatory Effect

The risk of heart attack is further reduced by the anti-inflammatory effect of the green tea catechins. The EGCG prevents the inflammatory reactions from occurring in the blood vessels of the heart. Occurrence of inflammatory reactions leads to a cascade of events that eventually reduce the supply of blood to the muscles of the heart. ^6-11

 

Anti-hypertensive Effect

Regular consumption of green tea helps to keep hypertension (high blood pressure) in check. The EGCG has a multitude of effects on the blood vessels, heart and other associated factors that control the blood pressure in our body. It has also been proposed that green tea catechins are responsible for lowering the blood pressure in certain instances. ^{9, 11}

 

Cholesterol Control and Stroke Prevention

High cholesterol (hypercholesterolemia) is a leading cause of heart and heart related disorders. The body requires certain amounts of cholesterol to function normally; however, high levels of cholesterol can have adverse effects. This is especially true in case of LDL cholesterol which is commonly referred to as bad cholesterol. Accumulation of high levels of LDL cholesterol can result in heart attacks and other related disorders. On the other hand, another type of cholesterol known as HDL or the good cholesterol has certain protective effect on the body. It has been observed that accumulation of LDL cholesterol is a leading cause of death due to heart related disorders in adults aged above 65 years. The youth are also not spared wherein an estimate states that about 36% of American youth have high LDL levels in their body. ^{12, 13, 14}  High levels of cholesterol are also associated with a higher risk of stroke which in turn has been attributed as the major cause of deaths related to heart disorders. ¹³

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Cancer Statistics

Cancer is a major cause of death all over the world and the incidence of cancer has increased significantly in the recent years. Unhealthy lifestyle habits, environmental and occupational hazards have contributed to this abnormal rise in cases of cancer. The World Health Organisation (WHO) has reported that the increase in number of people being affected with cancer in the developing countries can be due to a multitude of factors such as: tobacco use, alcohol use, low fruit and vegetable intake, and chronic infections from hepatitis B (HBV), hepatitis C virus (HCV) and some types of Human Papilloma Virus. In case of developed countries, along with factors such as tobacco use and alcohol use, overweight and obesity have also been associated with an increased risk of cancer. ¹⁷ 

 

It was estimated that more than 12 million cases would be reported by the end of the year 2007 with the number of associated deaths being 7.6 million (almost accounting to 20,000 deaths every day). In case of the United States, it was estimated that about 1,437,180 new cancer cases would be diagnosed in 2008 with the number of deaths associated with cancer would be more than 1,500 per day. ¹⁸ 

 

Anti-cancer Effect of Green Tea

Green tea has been found to have a significant role in the prevention and treatment of different types of cancer. This property has been mainly attributed to the polyphenol EGCG. Various studies have reported the cancer preventive role of EGCG on regular consumption. Abnormal growth of any cells or tissues is commonly referred to as cancer. Numerous medications and other modes of treatment are advised for treatment of cancer and they have delivered varying results. These treatment modalities are also associated with a number of adverse effects. In the midst of these the proven anticancer role of green tea has resulted in the increase in the consumption of green tea all over the world.

 

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Green Tea Prevention For Different
Types of Cancers

Green tea has beneficial effects in a number of types of cancers ranging from skin cancers to prostate cancers. Interestingly the polyphenols and other active compounds in green tea play a diverse role in each type of cancer ultimately resulting in the cancer preventive effect.

 

Skin Cancer

The skin cells in our body are the most vulnerable to the ultraviolet radiation being emitted by the sun. Prolonged exposure to this can result in skin cancer in many individuals. Regular consumption of green tea helps in the prevention of this in a number of ways. The damaged skin cells are repaired, the suppressed immune system of our body is regenerated, the growth of cancer cells is suppressed and the immune cells against cancer cells are activated. ^{24, 25}

 

Breast Cancer

Regular consumption of green tea reduced the incidence of breast cancer in susceptible women when compared to those women who did not consume green tea. The tea polyphenols may have a preventive effect on the occurrence of breast cancer. Although only a few studies have reported this effect, the benefits of green tea cannot be ignored. ^{26, 27} 

 

Ovarian Cancer

A study in China reported that the incidence of ovarian cancer in women who drank green tea quite frequently was significantly reduced. A similar kind of results were obtained in a study in Washington wherein it was noted that the risk of ovarian cancer reduced by 54% in women who consumed more than 1 cup of green tea every day. These studies have highlighted the beneficial effects of green tea and have initiated further studies in the same field. ^28-30 

 

Prostate Cancer

Green tea has both preventive and curative properties according to a number of epidemiological and laboratory studies. Prostate cancer, which resulted in over 29,000 deaths in the US, has been rated as the second most common cause of deaths related to cancer in men. ³¹

 

Cancers of the Gastrointestinal Tract

In the gastrointestinal tract (GIT), green tea has been proposed to benefit individuals with an increased risk of gastric cancers, liver and colon cancers.
In case of gastric cancers, the antibacterial, anti-inflammatory and anticancer effects of green tea have been attributed to the decreased incidence. Gastric cancer is commonly caused by a microorganism known as H. Pylori. Green tea prevents the collection and multiplication of this agent and also its destructive capabilities. Furthermore, green tea reduces the inflammation and the precancerous changes induced by these organisms. ^{23, 32, 33}

Regular consumption of green is associated with the decrease in the formation and growth of cancer cells in the colon and the liver. It may also cause the death of cancer cells in case of colon cancer. ^{34, 35} 

 

Benefits in other Conditions

Apart from anti-cancer and other protective actions on the heart, the green tea polyphenols have been found to have beneficial effects in numerous other disorders:

 

Neural Disorders

As one grows older the incidence of disorders associated with advancing age also tend to increase. This is commonly true in case of disorders affecting the nervous system. Most commonly noted nervous disorders in the older individuals include dementia, Alzheimer’s disease and Parkinson’s disease. These neural disorders are all associated with altered functioning of the nerve cells either due to a deficiency of certain hormones or due to abnormalities within the nerve cell itself.

Consumption of green tea regularly may decrease the occurrence of these neural disorders in the susceptible individuals. EGCG in green tea is considered to have certain neuroprotective properties that have beneficial effects such as stabilisation of the abnormal nerve cells to help them conduct the signals more efficiently and systematically.

 

Another green tea benefit is its iron chelating ability. Green tea polyphenols are capable of breaking down certain insoluble forms of iron that tend to get collected in various parts of the body including the brain cells. It has been believed that one of the risk factors in the neural disorders is the increased amount of iron being collected in the brain cells. Green tea may have a protective effect in such cases thereby preventing the occurrence of these disorders. ^{36, 37}

 

Weight Loss

Weight gain is primarily associated with increased deposition of fat within the skin cells over certain specific areas in the body. The phytochemicals of green tea have a multipronged effect that prevents storing fat in many instances. Green tea increases the activity in the cells and tissues of the body which result in burning up of these extra calories thereby preventing their storage.38, 39  The formation of fat cells in the body is kept under check with regular consumption of green tea.

 

Chronic Obstructive Pulmonary Disease (COPD)

Chronic smoking and environmental pollution have been associated with the increased occurrence of various disorders of the lungs among which chronic obstructive pulmonary disease (COPD) is considered as a major disorder. The anti-oxidant and anti-inflammatory effects of green tea is beneficial in such disorders wherein the main symptoms occur due to inflammation of the lungs cells and tissues. Consumption of green tea along with the advised medications has been reported to reduce the severity of symptoms in COPD patients. ⁴⁰

 

Diabetes Mellitus

The role of green tea in the prevention and treatment of type 2 diabetes mellitus is being studied extensively. The breakdown of glucose in the liver cells may be affected by certain enzymes in individuals suffering from diabetes mellitus which may lead to increase glucose levels in the blood. The green tea polyphenols are believed to inhibit the action of such enzymes thereby helping the liver to function more efficiently. Furthermore, the production of glucose within the liver is also reduced to a certain extent. ⁴¹

 

Eye Ailments

The antioxidant and anti-inflammatory effect of green tea also serves in preventing or delaying the progression of certain age related eye disorders like cataract, glaucoma and macular degeneration. ⁴²

 

Oral Health

Periodontitis (also referred to as pyorrhoea) is the term used by dentists to refer to the infection and inflammation of the gums. This condition is commonly associated with bleeding from the gums and bone loss around the teeth which may lead to teeth loss. A number of microorganisms have been identified as the factors that aid in the progression of gum disorders along with other local factors. Green tea polyphenols are beneficial in gum diseases as they prevent the progression of these microorganisms and also protect the bone forming cells to a certain extent.43  Other conditions that may be benefitted with regular consumption of green tea include Sjogren’s syndrome and dental caries. ^44-46

 

Infections

The antibacterial, antiviral and antifungal effects of green tea polyphenols help in controlling the growth of numerous microorganisms in the body which are known to produce certain toxic substances that may have detrimental effects on the cells and tissues of our body. It has been proposed that the catechins also can neutralise the toxic substances produced by these microorganisms. ⁴⁷

 

Skin Care

Green tea bags can be now carried along with your sun tan lotion. It has been noted that regular consumption of green tea protects the skin against various insults of UV rays such as sunburn and aging. The green tea polyphenols are also known to accentuate the effects of sunscreen products. ²⁵

 

See Also:

Brewing Green Tea Optimally
for Health Benefits

General Serving Tips

References & Safety Concerns