Health Benefits of Drinking Green Tea: The Science

A tea plantation in India. Photo author: Rightee CC-BY-2.0
A tea plantation in India. Photo author: Rightee CC-BY-2.0 | Source

In Asian, and especially Chinese cultures, legends abound of the health properties of green tea. Some varieties have the reputation of curing all illness, others of sharpening the mind, others of focus and concentration. There are legends of some types of green tea being served to scholars and wise men who visited towns and villages in ancient times; and in the present, some varieties of tea have a protected status and to earn their name they must originate from trees growing in certain areas.

With thousands of years of claims, myths and legends behind it, it’s not surprising that the fame of green tea has spread from the Asian countries where it is grown, to Western countries where it is being embraced with enthusiasm.

But is green tea all myths and legends? Is it simply a drink like any other, for hydration and enjoyment? Or does it really have those outstanding benefits for health and happiness? Here is a round-up of some of the many claims of green tea that are backed up by hard scientific research as well as thousands of years of tradition. There are links at the end of each section that will take you to abstracts of original research that has investigated the properties of green tea scientifically.

Anatomy of the Heart.  Photo by Tvanbr. Public Domain image.
Anatomy of the Heart. Photo by Tvanbr. Public Domain image. | Source

Curing Disease


Babesia is a parasitic infection of the blood that often occurs in conjunction with tick-borne diseases in humans. Scientists at Obihiro University in Japan conducted an experiment on both cows and rodents whereby creatures infected with Babesia were given an extract of green tea, a substance called EGCG. The researchers found that the parasites were gone completely by the 16th day of treatment with the green tea extract.

The amount of EGCG given to the animals was equivalent to that found in about 4 cups of green tea for people of around average body weight.

Although no human trials have been done, green tea has been shown to be safe even if much higher amounts are drunk.

Abstract of Babesia and green tea research paper

Heart Disease

Researchers at The University of Western Australia found that both black and green tea protect to some degree against cardiovascular disease. Although the researchers were not able to pinpoint the reason why tea exerts this protective effect, they identified various potential areas where tea improves how the immune system works against disease, and how green tea helps our bodies function at their best.

The findings of the research are backed up by very large scale 'population studies' which show that people who consume black or green tea regularly are up to 20% less likely to suffer cardiovascular disease than people in the same population who do not drink tea.

Abstract of cardiovascular disease and green tea research paper


In cases of stroke, and possibly other conditions that attack the brain, green tea has been found to exert a neuroprotective effect. Recovery from stroke has also been found to be faster and more complete in those already drinking green tea before the stroke occurs.

Abstract of Stroke and green tea research paper


There are many hundreds of studies which show that green tea may prevent some cancers, and may aid recovery from others. The research is at an early stage as yet, and the reasons why green tea might help are still not fully understood, but much of the research in this area focuses on amounts of green tea extracts that are equivalent to drinking a few cups of green tea per day, and many have proposed that it is possibly due to tea’s anti-oxidant and anti-inflammatory effect.

An abstract of one of the many research papers on green tea and cancer

Lung Health

There is growing evidence from research that green tea has a great beneficial effect on lung health, not least on those who either smoke or who are subjected to second-hand smoke, because it helps the body ‘clean up’ and neutralise free radicals – molecules that can wreak toxic damage in our bodies. Interestingly, since green tea has this antioxidant property, it may also help to provide some relief from symptoms of many different conditions that are thought to be worsened by the same mechanism, such as Alzheimer’s, Parkinson’s, Schizophrenia and many more.

Some research on green tea's beneficial effect on lung health


At the Karolinska Institutet in Stockholm, researchers found that in an animal model of diabetes, mice fed with an extract of green tea had enhanced glucose tolerance, so green tea may thus offer a dietary method of improving the condition in diabetics. Like most of the research into green tea, research on diabetes is still at an early stage, but the results look promising for the future.

Green Tea and diabetes research

Sir Alexander Fleming, discoverer of penicillin.  Public domain image.
Sir Alexander Fleming, discoverer of penicillin. Public domain image. | Source

Aiding Modern Medicine

Antibiotic Enhancement

Researchers in Egypt needed to investigate how green tea might affect antibiotics because it is such a popular drink there, and it has quite a wide range of possible effects. The researchers found that antibiotics worked much better at fighting disease in those who regularly drank green tea, and it even made some antibiotic-resistant diseases susceptible again. To my knowledge, there has been no further research yet on this area, although similar results were found by researchers at the Showa University School of Medicine in Tokyo where low doses of antibiotics in combination with green tea were shown to combat H. Pylori – the bacteria responsible for stomach ulcers.

A report by Science Daily on green tea's enhancing effect on antibiotics

Research abstract on green tea and antibiotics combination to fight H. Pylori

Happiness and Well-Being

Anxiety, Mood enhancement, Focus and Concentration

One of the most important beneficial substances in green tea is called l-theanine (often called simply ‘theanine'). Theanine has been shown to promote relaxation, focus and learning, and has also been linked to other benefits associated more generally with green tea, such as improving the immune system and preventing chronic disease. Whilst theanine as an extract has been studied, it is also thought by many that some of the fabulous effects of theanine in reducing anxiety and enhancing mood, focus and concentration, are due to the combination of theanine with some of the other substances a cup of green tea naturally contains, like EGCG, antioxidants, and low levels of caffeine.

Some research on l-theanine

Photo author: Lykaestria. CC-BY-3.0
Photo author: Lykaestria. CC-BY-3.0 | Source

Repairing Damage


The sun’s rays, in particular UVB and UVA, are responsible for both long-term skin damage – that is, damage that can develop over time into skin cancer – and damage to the eyes that can contribute to macular degeneration, which is one of the leading causes of blindness in older people. EGCG found in green tea has been found in a number of research studies to halt the damage to skin and eyes caused by the sun. Since sun exposure also causes aging of the skin, this protective effect from the sun’s rays may go some way to explaining why green tea also keeps us looking young.

Green Tea and UVB research

Green Tea and UVB research

Green Tea antioxidants as possible sun-protection research


One of the reasons why memory gets worse as we age is because of a build up of toxins and metals in the brain over long periods of time. Green tea is not only excellent at flushing out toxins through its abundance of antioxidants, but it also ‘binds’ to molecules of damaging metals and sweeps them away. Researchers have found that to get – and maintain – this memory-enhancing effect, you need to drink a few cups every day.

Green Tea protective against neurodegeneration - abstract of research paper

Weight Loss

A study in Tokyo, at the Health Care Food Research Laboratories of the Kao Corporation, showed that over a three-month period, people who drank green tea high in catechins (the ‘good stuff’ that’s found in large amounts in fresh loose-leaf green tea) lost markedly more weight than people who did not. An additional benefit was found in that those drinking green tea also had decreased ‘bad’ cholesterol levels as well as losing weight.

Tokyo research on green tea and weight loss

Osteopenia and Osteoporosis

In women, bone density decreases as we age, and after the menopause we’re at risk of conditions like osteopenia and osteoporosis, conditions that can lead to very fragile bones that break easily. There has been a lot of research on how exercise can help to prevent these conditions, and in particular Tai Chi has been found to help. What is more surprising is that research has also found that the polyphenols in green tea also caused a marked improvement in bone renewal in women with osteopenia over just a one-month period. In a comparison study, Tai Chi on its own improved the rate of bone renewal over a three-month period; green tea improved bone renewal over a one-month period; and further improvement was seen over longer periods. Muscle strength was also improved by both Tai Chi and green tea. The amount of green tea polyphenols given to the women in the study was equivalent to about 4-6 cups of green tea per day.

Research abstract on osteopenia, green tea and tai chi

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Comments 15 comments

bridalletter profile image

bridalletter 4 years ago from Blue Springs, Missouri, USA

Looks like I will return to drinking tea daily, with so many potential benefits. Wow! Some of the items you found, I truly never knew before. The antibiotics, that is worth sharing.

mecheshier profile image

mecheshier 4 years ago

Nice Hub... informative, insightful and a great read. Thank you. Voted up

nancynurse profile image

nancynurse 4 years ago from Southeast USA

I drink lightly sweetened green tea I buy at Costco. Glad to know I am doing something good for myself. Great hub!!!!

Redberry Sky profile image

Redberry Sky 4 years ago Author

Thanks, bridalletter, yes, some of the research is digging up amazing things about the humble cuppa

Cheers, mecheshier, glad you enjoyed it.

nancynurse, thank you, yes, we'll all wake up twenty years younger if we keep drinking it ;) - or at least we'll be healthy :)

catmalone profile image

catmalone 4 years ago

Great Hub! I like green tea. I drink it twice a day due to the health benefits.

Redberry Sky profile image

Redberry Sky 4 years ago Author

catmalone, cheers :) you're storing up a healthy future then!

Mhatter99 profile image

Mhatter99 4 years ago from San Francisco

Thank you for this. i drink green teas because i like them :-)

Redberry Sky profile image

Redberry Sky 4 years ago Author

Mhatter99 - that is, of course, one of the most important reasons of all to drink green tea :)

Angela Brummer profile image

Angela Brummer 4 years ago from Lincoln, Nebraska

Great hub! Really fantastic information with explanation.

Redberry Sky profile image

Redberry Sky 4 years ago Author

Cheers Angela :)

molometer profile image

molometer 4 years ago from Cambridgeshire, England

Great information and really helpful and useful. I have had green tea but wasn't to keen. I will have to give it another go.

Redberry Sky profile image

Redberry Sky 4 years ago Author

molometer - was it the bagged green teas you've had in the past? - they can taste a bit old and stale, but if you haven't already tried one, a nice fresh green tea from the latest harvest is something else - it really is a whole different taste and scent.

Laura 4 years ago

This Was a really good Read. I drink 2 cups of Green Tea every day, i will defiantly be drinking more now :). At first the taste was quite vile, like drinking perfume, but now i have been drinking it for a month i don't mind the taste now!

Redberry Sky profile image

Redberry Sky 4 years ago Author

Hi Laura, you're right, it can taste a bit odd if you haven't tried it before, but like you say, it does become enjoyable quite quickly. Cheers for stopping by and commenting :)

Samprita profile image

Samprita 22 months ago from Indore, India

I am a great fan of green tea... Just wrote a hub on effects of tea on teeth and some of the health benefits of green tea but missed out on some.. will share this hub.... Thanks...

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