The health benefits of Japanese green tea
Japanese green teas such as Matcha are becoming all the more popular outside of Japan, infiltrating trendy cafés and coffee shops the world over. And with good reason. While the Japanese have long considered green tea to be protective against a wide range of chronic diseases, it is only recently that science has caught up, with a stream of recent research supporting many of these health claims.
From protection against cardiovascular diseases, improved cognitive function and even the moderation of allergies, there seems to be no end to the reported health benefits of green tea, and the research is ongoing. There is little wonder that green tea is repeatedly praised as “the healthiest beverage on the planet”.
A unique suite of antioxidants
It seems that green tea has the bioflavonoidal compounds called catechins to thank for its host of health benefits - a special group of antioxidants unique to the tea plant, which are especially well-preserved in the less refined and fermented green tea. Antioxidants are those wonder micronutrients that fight free radicals and so protect our cells and DNA from the damaging effects of the modern environment.
As well as the more familiar antioxidants Vitamins A, C and E, which all contribute to slowing the effects of ageing caused by the likes of sun exposure, alcohol and smoking, the antioxidants catechins - and especially the catechin EGCg – appear to have much wider ranging health benefits. The Japanese green tea Sencha is particularly rich in catechins as it is grown in direct sunlight, although all varieties of green tea contain these health-boosting compounds.
Antiviral and antibacterial
Catechins are antiviral and antibacterial as well as antioxidant, with recent research demonstrating their ability to stave off and reduce the symptoms of viral infections such as influenza. The study, which looked at the benefits of both gargling with and ingesting Japanese green tea, found that the beverage was even effective against the new H1N1 strain  .
The immuno-properties of green tea are so powerful that as well as fighting internal infection, topical use of a green tea ointment has even been successful in clearing external skin infections .
Catechins in green tea may help to prevent various heart conditions, lower blood pressure, prevent blood clots and increase blood flow in the arteries. There are indications that they may improve cholesterol levels by raising the levels of good HDL cholesterol and inhibiting the formation of bad LDL cholesterol. Not only this, but they may stabilise blood sugar and reduce the risk of diabetes .
Catechins don't take all the green tea health-giving glory, however. Tea is also the only plant to contain the amino acid theanine, a compound capable of crossing the blood-brain barrier and aiding brain functioning. Theanine is said to promote a calm yet alert state of mind by causing the brain to switch to alpha brain waves, which promote relaxation.
What's more, the synergistic effects of theanine and caffeine – also found in small doses in green tea – can have even greater effects upon cognitive performance. Theanine counters the negative effects of caffeine, reportedly leading to a state of relaxed clarity and concentration, perfect for work, study or meditation.
A natural antidepressant?
Theanine is also claimed to have positive effects on mood, due to its ability to interact directly with neurotransmitters in the brain. It appears to increase the levels of the mood-boosting neurotransmitters dopamine and serotonin, along with the anti-anxiety GABA.
The highest levels of theanine are to be found in green teas that have been grown in the shade, such as Matcha and Gyokuru. The first pick of the year, Ichibancha, and the premium tea Karigane, also contain high levels of theanine.
Certain studies have shown that green tea can increase metabolism and aid in weight loss. While the jury is still out on this one, the negligible number of calories found in green tea make it a great choice for those looking to lose weight or just stay in shape.
While it may be low on calories, Japanese green tea packs a real punch when it comes to vitamins, minerals and phytonutrients. As well as the vitamins and antioxidants already mentioned, it also contains significant levels of manganese, potassium, calcium, chromium and selenium.
One way to maximise your uptake of these valuable nutrients is by drinking Matcha tea, a form of green tea in which the whole leaves are ground into a powder and consumed with hot water. A cup of Matcha tea contains every one of the nutrients contained in the tea leaves – even the non-water-soluble ones and the dietary fibre.
Want even more bang for your green tea buck? Research has shown that drinking the Japanese green tea Benifuuki prior to the pollen season can considerably reduce symptoms for pollen allergy sufferers . The antibacterial catechins can help with oral health by killing germs in the mouth and combating bad breath, and have even been said to prevent cavities. They may even get a look in towards the end of life by protecting the brain against neurodegenerative diseases such as Alzheimer’s and Parkinson’s, and by reducing the risk of stroke.
Studies are ongoing with regards to green tea's cancer-fighting effects, but research has shown green tea consumption to be associated with reduced risks for certain cancers such as breast, ovarian, endometrial and colorectal cancers. One study on men with a precancerous prostate condition successfully reduced the number that went on to develop full prostate cancer when compared to a controlled placebo group  . In vitro studies have also demonstrated how green tea can destroy cancer cells , but such effects are yet to be seen in human trials.
This area of research is still in its infancy, and although there are no definite conclusions to be drawn just yet, the future looks promising. And with so many other health benefits going for it, the decision of whether to switch to drinking Japanese green tea is really an easy one to make.
- Yamada H, et al. Gargling with tea catechin extracts for the prevention of influenza infection in elderly nursing home residents: a prospective clinical study. 2006 Sep;12(7):669-72., J Altern Complement Med., pp. 669-72, 2006.
- Matsumoto K, et al. Effects of green tea catechins and theanine on preventing influenza infection among healthcare workers: a randomized controlled trial, BMC Complement Altern Med. , 2011.
- Gupta A., et al. Sinecatechins 10% ointment: a green tea extract for the treatment of external genital warts, Skin Therapy Lett., pp. 6-8, 2015.
- Huxley, R. et al. Coffee, Decaffeinated Coffee, and Tea Consumption in Relation to Incident Type 2 Diabetes MellitusA Systematic Review With Meta-analysis, Arch Intern Med. , 2009.
- Yamamoto, M. et al. Yamamoto, M. (2012) Anti-Allergic Action of O-methylated EGCG in Green Tea Cultivar Benifuuki, Journal of Food and Drug Analysis, 2012.
- Brausi M., et al. Chemoprevention of human prostate cancer by green tea catechins: two years later. A follow-up update, Eur Urol., pp. 472-3, 2008.
- Bettuzzi S., et al. Chemoprevention of human prostate cancer by oral administration of green tea catechins in volunteers with high-grade prostate intraepithelial neoplasia, Cancer Res., pp. 1234-40, 2006.
- Paschka A.G., et al. Induction of apoptosis in prostate cancer cell lines by the green tea component, (-)-epigallocatechin-3-gallate, Cancer Lett., pp. 1-7, 1998.