Health A-Z Archives: Green Tea


Green tea is the same plant as ‘black tea’ known as Camellia Sinensis. Green tea has been used for stomach disorders, vomiting, diarrhea, to prevent dental cavities, to lower cholesterol levels, as an antioxidant, to reduce cancer, and as a stimulant.

Green tea has not been evaluated by the FDA for safety, effectiveness, or purity. All potential risks and/or advantages of green tea may not be known. Additionally, there are no regulated manufacturing standards in place for these compounds. There have been instances where herbal/health supplements have been sold which were contaminated with toxic metals or other drugs. Herbal/health supplements should be purchased from a reliable source to minimize the risk of contamination.

Are There Any Benefits?

In fact in my research on green tea, I can find no detailed facts on the so-called “amazing antioxidant properties” that are claimed. Some sources claim it contains 3 x the beta carotene of carrots and 5 times the Vit C of lemons, but as Vitamin C is ‘water soluble’ it is destroyed by the drying process; and, if any remains months later when you place it in your cup, it will be destroyed by the boiling water!! I cannot see how something that is clearly not a food ie. you cannot make a meal out of it – can be as nutritious as claimed!

Then, all the information available on the internet is from people who have a vested interest in promoting green tea! To date I have not found one independent source.

The Negative Aspects of Green Tea

The main negative side effect reported from drinking green tea is insomnia due to the fact that it contains caffeine. This clearly indicates that the green tea is having a negative effect on the neuro-endocrine system, as it is these systems that regulate sleep. However, green tea contains less caffeine than coffee: there are approximately thirty to sixty mg. of caffeine in six to eight ounces of tea, compared to fifty to hundred mg. in eight ounces of coffee. The same as black tea and instant coffee.

There is some research to indicate that people who drink more green tea may have a higher metabolic rate, but what is not documented is whether these people consume less food, exercise more, eat more overall fruit and vegetables etc. For example the more fruit and vegetables you eat, the better your metabolism will be. This is because fruit and veg have an alkaline effect on the body and it is this (plus regular physical exertion) rather than some magic ingredients that will help you control your body weight. Caffeine is known to both rev up and slow down metabolism, but in the long term it can have a negative effect on the hormonal system and can contribute to high blood pressure, diabetes, arthritis, gout, infertility and sterility, poor muscle tone and cellulite to name but a few. In fact any of the research I have read to date on green tea, involves just a small group (maximum 1000 odd but averaging 10-20) of people over a short period of time from 24 hours to 2 weeks. This is actually a joke and not nearly enough time to see any potential side effects

Sources of Catechins

Catechins constitute about 25% of the dry weight  (so added to hot water you get 25% of 1%!!) of fresh tea leaf, although total catechin content varies widely. They are present in nearly all teas made from Camellia sinensis, including white teagreen teablack tea and oolong tea.
Catechins are also present in the human diet in chocolate[3], fruits, vegetables and wine[4] and are found in many other plant species[5].

Health benefits of Catechins

The health benefits of catechins have been studied extensively in humans and in animal models. Reduction inatherosclerotic plaques was seen in animal models.[7] Reduction in carcinogenesis was seen in vitro.[8]

Many studies on health benefits have been linked to the catechin content. According to Norman Hollenberg, professor of medicine at Harvard Medical Schoolepicatechin can reduce the risk of four of the major health problems: stroke, heart failure, cancer and diabetes. He studied the Kuna people in Panama, who drink up to 40 cups of cocoa a week, and found that the prevalence of the “big four” is less than 10%. He believes that epicatechin should be considered essential to the diet and thus classed as a vitamin.

The problem with this type of research where people are looking for the silver bullet or the miracle cure is that total diet and lifestyle is not taken into account. It is known that these people live a generally healthier lifestyle than the average westerner, with more exercise outdoors, and an overall higher consumption of fresh fruit and veg and less animal protein. To isolate cocoa as the cure and then translate that to green tea is ludicrous! To say the least

According to one researcher, epigallocatechin-3-gallate is an antioxidant that helps protect the skin from UV radiation-induced damage and tumor formation. Catechin is a histamine decarboxylase inhibitor.

Who should not take green tea?

Green tea contains a large amount of caffeine and may be problematic if used by people with any of the conditions listed here; blood pressure problems (high or low), blood sugar problems (high or low), overactive thyroid, stomach ulcers, pregnant and lactating women, any one with stress or hormonal related disorders.

Do not take green tea if you are breast-feeding a baby. Green tea contains a large amount of caffeine, which may cause restlessness, sleep disorders, and other effects in breast-feeding infants. Caffeine is a central nervous system drug known to cause genetic mutations or DNA abnormalities.

There is no information available regarding the use of green tea by children. Green tea contains a large amount of caffeine and tannin, which may cause anemia and other problems in women & children – the most common deficiency disease among this group in western cultures. Do not give any herbal/health supplement to a child without first talking to the child’s doctor.

How should I take green tea?

If you want to take green tea, then only organically grown and decaffeinated should be used, but theobromine in tea may cause similar responses to caffeine.

What are the possible side effects of green tea?

Although rare, allergic reactions to green tea may occur. Stop taking green tea and seek emergency medical attention if you experience symptoms of a serious allergic reaction including difficulty breathing; closing of your throat; swelling of your lips, tongue, or face; or hives.

Heavy and prolonged consumption of green tea may be associated with esophageal cancer

Other less serious side effects have also been reported with the use of green tea such as heartburn, upset stomach, loss of appetite, constipation, nervousness, irritability, anxiety, sleeplessness, irregular heartbeat or headache.

Some research done in Geneva for example was during a 24 hour period on 10 men, not exactly reliable or accurate research at all!!

In depth details about Green Tea?

Green Tea comes from the same plant from which normal tea is obtained. Scientifically, it is known as Camellia Sinensis. In fact, it is the same tea but processed differently. The normal black tea is obtained by fermenting the tea leaves. This fermentation changes its colour, flavour and raises the level of caffeine and tannin in it. Whereas, in case of Green Tea, the tea leaves are dried or slightly steamed but not fermented. This makes it look green when brewed and otherwise.

Constituents: Apart from caffeine, which gives tea its characteristic taste, bitterness and stimulating effect, Green Tea is rich in a group of chemicals, called Catechin Polyphenols (Commonly known as Tannins which contribute to bitter taste and astringency) like Catechin, Epicatechin, Epicatechin Gallate (ECG), Epigallocatechin Gallate (EGCG), Pro-Anthocyanidins etc. They are also known as Flavonoids and are very powerful anti oxidants. Flavonoids, together with some amino acids like Theanine, are responsible for the flavour of Green Tea. Further, it also contains Amino Acids like Theanine, Butyric Acid & Liganin; Xanthine Alkaloids such as Adenine, Dimethylxanthine, Theobromine, Theophylline and Xanthine; Pectin (also found in fruits); saccharides (sugar), Chlorophyll and Triterpene Saponins. Some vitamins like vitamin A, B1, B2, B3, C and E are found in Green Tea.

All these nutrients are found in a wide variety of fresh and dried fruit and vegetables, there is therefore no sound reason to drink a beverage which can cause a variety of problems from infertility to gout and heart disease.

Health Benefits: The health benefits from Green Tea are said to be primarily due to its anti oxidizing properties which come from its Caffeine, Catechin Polyphenols and Theonine. These health benefits can be listed below:

• Anti Ageing:
• Stimulating: The main reason people want drinks containing caffeine and tannins, despite their adverse effects on health in the long run, is their stimulatory effect. That is why; a cup of tea makes you feel fresh and highly energized. Tea is used to counter fatigue, laziness, sleepiness and lack of energy and to improve blood circulation. No doubt it is so popular with many people especially in those high rise building so many work in.
• Immunity Boosting:
• Astringency:
• Anti Carcinogenic:

• Reducing Cholesterol:
• Anti Diabetic:
• Weight Loss:
• Stamina & Endurance Booster:
• De intoxicating: Anything with caffeine in gets rid of hangovers and fatigue caused by consumption of alcoholic beverages and lack of sleep due to late night parties.
It seems absurd that we live badly, get tired or hung over and then use a stimulant to rev us up to recover and then need to relax from the stimulants all day long and then have a drink to slow us down, which starts the whole process all over.

Types of Green Tea: 

Green Tea has four main varieties, prepared in Japan, which depend upon its leaf-length, method of processing, season of harvesting etc. They are as follows;

• Gyokurocha: In this case, the tea leaves are plucked from the tip of the branches. When brewed, the colour is clear green. Being picked from the tip, this variety has the best taste and fragrance. This is also considered best in terms of health and is less bitter, as it contains less tannin and caffeine, the leaves being younger and budding. The only drawback it has is that it is very costly.

• Sencha: Sencha Comes from the same plant, but this time, the leaves are from middle of the branch and are bigger, older and less tender than Gyokurocha and gives a clear, light green tea on brewing. Naturally, it is bitter and stronger than the former variety. Being of less noble origin (middle of the branch) and having more caffeine and tannin, it is cheaper and more popular than Gyokurocha.

• Bancha: Bancha is made from the tender twigs of the tea plant and but obvious, it is very strong and bitter. When brewed, it gives a golden brown tea. This is further cheaper.

• Matcha: It is the leftover powder of Green Tea, also called “Dust”. It makes a beautifully green coloured tea and forms a lot of foam (froth) as well, but has a lesser aroma than the leafy varieties. This variety of Green Tea is very popular in the Ceremonies, sometimes also called Ceremonial Green Tea. It is far less bitter than its formers and hence when you sip it, it feels as if it is sweeter than them.

• Houjicha: Also spelled as “Hojicha”, it is not a pure or absolute green tea. Rather, it is mixture of green tea and powdered roasted cereals such as wheat, barley, rice etc. The quality and price of this variety depends upon the percentage or ratio of green tea to cereals. The better ones, having more tea in them, are costlier and give greener tea; while those, having more grains, yield a golden brown colour and are cheaper.

• Genmaicha: Like Houjicha, it is not a pure tea either. It is mixture of Green Tea and roasted brown rice. On steeping, it yields a golden yellow tea, very nice in taste and aroma, due to presence of roasted brown rice in them.

• Decaffeinated Green Tea: not a variety, but it is also worth mentioning here. Any of the above varieties can come in decaffeinated form. This would be the best way to drink green tea if you really feel a need for it
Risks: The risks associated with Green Tea are same as those associated with any other kind of tea (Common Black Tea, White Tea etc.) and are primarily due to presence of Caffeine and Tannins in it. The contraindications may vary with the percentage of caffeine and tannins in it. Most of you might be familiar with these adversities, still, let me summarize the components responsible and the associated risks here;

•Triterpene Saponins: These compounds destroy the Red Blood Corpuscles (Erythrocytes) and thus may aggravate situations of anaemia, cause fatigue etc.

• Caffeine: Everybody knows that it is an external stimulant and raises blood pressure, actually toxic in nature (it may be fatal for lower animals), addictive and in the long run has adverse effect on liver and internal organs. But then, it is the thing in tea which makes it energizing and refreshing.

• Tannins: Tannins interfere with the breaking down of complex proteins into simpler proteins and their absorption in the body. 
• Xanthine Alkaloids: There are possibilities that they aggravate formation of uric acid in the body and thereby may trigger off and aid formation of stones in gall-bladder and kidneys, arthritis etc.

• Other Risks: Long term consumption and in greater quantities may give rise to problems such as insomnia, restlessness, annoyance, irritability, aggression, headaches, hypertension, abnormal heart-beats, loss of appetite, spasms, constipation and acute addiction to it. People addicted to it do can suffer from acute constipation, irritation and lack of concentration on anything in absence of Green Tea.

Decaffeination of Green Tea: There are two industrial processes and one domestic process, listed as follows;

• Industrial Process-1: In this, green tea leaves are treated with Ethyl Acetate, which drains out most of its caffeine (of course, with a lot of its anti oxidant Polyphenols and vitamins too).

• Industrial Process-2: This involves processing of tea leaves with water and carbon dioxide and is better in retaining the Polyphenols.

• Domestic Process: This is a very simple process. It needs repeated steeping of tea in hot water and throwing away the water (you may use this tea to serve those who don’t mind having caffeinated tea). The more you do so, the less caffeine left in the tea, but so is the taste and flavour. So, don’t over do it. Twice or thrice is reasonably good. After all, you want tea and not plain hot water. Isn’t it?

Additional Information: Did you know what the term “Cha” means in names of various teas as Gyokurocha, Sencha, Bancha, Matcha, Houjicha etc? It simply means “Tea”, and tea is popular all over India as “Cha” (In Bengal & adjacent states) and “Chai” in the rest parts.

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