My recent fabulous first trip to Japan – where green tea was EVERYWHERE and in everything – got me pondering why exactly green tea is regarded as good for you. Does green tea’s reputation really stand up to all the health hype? So I’ve looked at some of the most recent scientific papers (so you don’t have to!), and summarised it all for you here. And while I was at it, I found out how to make a proper cup of matcha, and I’ve come up with recipes for Iced Matcha Shake, Matcha Latte, and Matcha Affogato, which I’ve included here too. You’re welcome!
THE SCIENCE BIT
How does green tea affect your health?
o Nutrients in green (and black) tea
o Can green tea help prevent or treat some specific health conditions?
o Can green tea help with weight loss and management?
o Can green tea help control type 2 diabetes and blood sugar?
o Can green tea help prevent heart disease and reduce cholesterol and blood pressure?
o Can green tea help prevent cancer?
o Can green tea help prevent tooth decay?
o Will green tea do you any harm?
• Green tea is available everywhere in Japan in many different varieties, and is included in many different types of drinks and sweet (and savoury) foods.
• Drunk regularly, green tea can improve your intake of some vitamins, minerals and substances considered to be antioxidants. Matcha has a much higher concentration of nutrients than black tea (e.g. English breakfast tea) and, for many nutrients, more of them than other types of green tea made by brewing leaves. Matcha is also high in caffeine. For many people, matcha’s ‘grassy’ taste is an acquired one.
• The jury is still out on just how much green tea may contribute to reducing the risk of certain chronic diseases. So far, results of scientific studies have been mixed, and there have not been enough large, good quality, studies.
• On balance, the latest science suggests green tea may be associated with a moderate reduction in the risk of some chronic diseases, and in particular breast and prostate cancer, high LDL (the bad type of) cholesterol and high blood pressure. And the chances of it doing you any harm are very low.
• Contrary to popular belief, the results of many scientific studies taken together have demonstrated green tea to have only a negligible impact in weight loss.
• On the basis of everything I’ve read, I’m going to be increasing the amount of matcha green tea I drink and use in cooking, as a positive contribution to my nutrient profile and overall health.
It will be no big surprise that I encountered a lot of green tea in Japan. But during my first trip there in February, I was still surprised by just quite how culturally prevalent it is. From the minute I hit Arrivals at Tokyo’s Narita Airport, several different brands of beautifully packaged green tea cans and bottles competed for attention in the convenience shop fridge.
As a typical first time visitor who was, until then, only familiar with the obvious Japanese dishes, plus a few others (sushi, sashimi, noodles, teriyaki chicken, you know the kind of thing), I found Japanese food culture to be surprisingly and fantastically diverse and regional. But in all the big cities and smaller towns I visited, green tea was something that was definitely everywhere, including in the vending machines which are in all the metro stations and in the streets. It also appeared in some form – whether as a drink or incorporated into dishes – in most food shops and restaurants.
The city of Uji – famous for its centuries’ old tradition of fine quality green tea production – is in Japan’s Kyoto prefecture. In Kyoto city, the proliferation of green tea went into absolute overdrive and it seemed to be in everything, including ice cream, biscuits, jelly sweets, rice wafers, cream buns, and the quintessentially Japanese, and highly addictive, mochi sweet glutinous rice cakes. There are also several different varieties of green tea-flavoured Japanese KitKats (and you can read all about the bonkers and surreal world of Japanese KitKats in a dedicated post coming very soon).
Twenty or so different types of tea are grown throughout Japan, although the most renowned tea cities, which have varieties named after them, are Uji, Kagoshima and Shizuoka. Kyoto, and the surrounding area, is renowned for producing the highest grade Japanese green tea, through a combination of mineral-rich soil and a mild misty climate with an optimum balance of rain and sun.
All tea comes from the same plant, Camellia Sinensis, native to East and Southeast Asia and the Indian Subcontinent, and is categorised into three types, depending on the level of fermentation. Green tea is unfermented, oolong is partially fermented, and black tea – such as English breakfast tea – is fully fermented.
Most tea drunk in Japan is green, and it wasn’t until I visited that I properly made the distinction between the different types of green tea – in particular, between leafy green tea, of the type most commonly drunk as an infusion in the UK – and powdered matcha green tea, which in the UK currently has a smaller fanbase and is found mostly in health food shops. The specific growing conditions, processing methods, and parts of the plant used, contribute to the different taste, look and nutritional content of different types of green tea. Some taste quite astringent, while others are more smooth and aromatic, and so pair with different foods and occasions.
These are some of the tea types most commonly found in Japan:
Matcha is the powdered form of green tea used in the traditional Japanese tea ceremony. At the point when new shoots on a tea bush have a few leaves, they are shaded from sunlight for two to three weeks before picking. This retains a high caffeine content and preserves green chlorophyll in the tea leaves, as they cannot undergo photosynthesis. Top-grade matcha is bright green – lighter-green varieties taste sweeter than the best matcha, and darker ones are more astringent.
Tencha (that is, matcha before it is ground to a powder) is then made by steaming the leaves and drying them, removing the leaf veins and fine stems and grinding the remaining leaves into a fine powder. Matcha tea as a drink is made by vigorously whisking this powder into water and consuming the lot (see the recipes section below), meaning that the whole leaf is consumed. Therefore matcha provides considerably more nutrients overall than green tea made from a brewed tea bag.
I think it is fair to say that matcha is a taste that you may need to acquire. It is strong, and tastes ‘green’ and very ‘chlorophylly’, reminiscent to me of wheatgrass shots I’ve had in a whole food shop. The Japanese categorise this as a umami flavour (that is, a savoury ‘meaty’ taste) which goes well with sweet things, although matcha can also be added to savoury dishes such as soups.
Sencha is the medium grade green tea – tasting mildly astringent but delicately sweet – which is the most popular tea in Japan, drunk throughout the day and after meals. It is made from the steamed and dried leaves of the first picking of the tea bush – anytime between late February and late May – and is high in vitamin C.
Fukamushicha is made in the same way as sencha, except the leaves are steamed two or three times longer and so become withered and darker. The taste remains sweet and moderately strong, but the fragrance becomes richer and deeper.
Sencha and fukamushicha together account for 75% of Japanese tea production. They are often drunk as an infusion from the leaves, although they also come in whole-leaf powder versions to be drunk, like matcha, after whisking into water. Except for vitamins C and E, these teas provide fewer nutrients than matcha, but still considerably more than black tea leaves.
Bancha is ordinary grade green tea – actually a brownish colour – intended for daily consumption and often served free in restaurants in Japan. It is made from the tougher tea leaves appearing between June and October after sencha leaves have been picked, along with upper stems and larger leaves discarded during sencha production. It is more astringent (i.e dryer-tasting, because of increased tannins) and less fragrant than sencha, and so tends to be favoured in Japan after a heavy meal.
Hojicha is produced by roasting bancha or sencha over a high heat, resulting in brownish leaves with a savoury fragrance. Containing relatively little caffeine and tannin, it is regarded as being the most suitable tea for children.
Konacha (‘tea powder’) has a strong colour, flavour, and fragrance, and is the tea served at sushi restaurants in Japan, where it is known as agari. It is made from the rejected buds and tea dust left over from the processing of sencha and gyokuro, a top-grade, rich green tea made in the same way as tencha (unpowdered matcha).
How does green tea affect your health?
When I saw all the ice-cold, unsweetened and neat-green tea options in Japan’s vending machines, I thought how much healthier it was to have those as an on-the-hoof drink choice – even if only for the lack of sugar, high fructose corn syrup and artificial sweeteners contained in so many Western grab-and-go options. But beyond that, my interest was also sparked in how much more ‘healthy’ green tea really is.
For those of you who like reading nutrition labels(!), I came up with the table below to allow you to compare the amounts of different nutrients typically found in matcha; leafy green tea (sencha); and black tea (English breakfast tea, for instance).
Table of Nutrients in Black Tea, Sencha leaves and Matcha powder per 100g of powder or leaves (figures given in brackets are for a made drink i.e. a typical cup of sencha or black tea brewed from leaves, and a typically-sized cup of matcha made with 2g of matcha powder)
|Nutrient||Unit||Black Tea (leaves)||Matcha (powder)||Sencha (leaves)|
|Energy||Kcal||311 (1)||324 (6.48)||331 (2)|
|Protein||g||20.3 (0.1)||30.6 (0.72)||24.5 (0.2)|
|Fat||g||2.5 (0)||5.3 (0.1)||4.7 (0)|
|Carbohydrate||g||51.7 (0.1)||38.5 (0.8)||47.7 (0.2)|
|Vitamin A||Mg||0.9 (0)||2.4 (0.04)||2.4 (0.04)|
|Vitamin E||Mg||11.4 (0)||28.1 (0.6)||78.6 (0)|
|Vitamin C||Mg||0 (0)||60 (1.2)||260 (6)|
|Vitamin K||Mcg||1,500 (minimal)||2,900 (58)||1,400 (minimal)|
|Mcg||210 (3)||1,200 (24)||1,300 (16)|
|Potassium||Mg||2,000 (8)||2,700 (54)||2,200 (27)|
|Calcium||Mg||470 (1)||420 (8.4)||450 (3)|
|Magnesium||Mg||220 (1)||230 (4.6)||200 (2)|
|Fibre||g||38.1 (0)||38.5 (0.8)||48.5 (not measured)|
|Caffeine||g||2.9 (0.03)||3.2 (0.06)||2.3 (0.02)|
|Tannin||g||11 (0.1)||10 (0.2)||13 (0.07)|
I’ve based these numbers – indicating many of the key nutrients that are contained in tea in significant quantities – on a translated extract of figures produced by the Japanese government (there is a more detailed table available online if you’re interested.)
You can see from the figures, for instance, that, unlike black tea, a cup of green tea contains vitamin C, and also more folic acid and minerals like calcium, potassium and magnesium. However, sencha contains more vitamin C and E than matcha, because its leaves have been allowed to grow in the sun and photosynthesise.
Matcha, and green tea extract used in supplements, also contains a higher concentration than black and oolong tea of what are considered by many to be the ‘active’ components for things like weight loss – that is, caffeine and catechins.
Of course, you will most likely be familiar already with the alertness and other day-to-day effects that caffeine can provide. I don’t plan to go into caffeine or its specific health impacts in detail here, which need to, and will, be the subject of a whole post of their own at a later date. But historically, most Buddhist monks in Japan have used caffeine, particularly through consuming matcha, to promote wakefulness and alertness for meditation. Anecdotally, people who meditate regularly in the mornings apparently report that tea does not interfere with the experience of mindfulness, in contrast to the ‘rush’ and agitation that caffeine consumed in coffee sometimes might cause.
So I’m taking it for now that you’re familiar with caffeine, but you may be less familiar with catechins. These are a type of flavanol, which is a type of flavonoid, which is the biggest sub-class of polyphenols. You may have heard of any or all of these substances, and they are all considered to have antioxidant activity. There are lots of catechins in tea and they are also found in fruits, vegetables, cocoa and wine. Harsher processing involved in black tea production means that green tea retains many more of its catechins than black tea does. Epigallocatechin gallate (EGCG) is the most abundant catechin found in green tea, and is included in many dietary supplements (just Google ECGC supplements, and see how many come up).
Many people believe that catechins are beneficial to human health through antioxidant activity, although as at 2015, neither the Food and Drug Administration in the United States, nor the European Food Safety Authority (EFSA – which currently sets the framework for most food-related legislation in the UK, including for health claims applied to food) had endorsed the health claims many companies had been making about catechins, apart from in one instance for cocoa. Some companies selling green tea have had their knuckles rapped for making health claims which were exaggerated and unsubstantiated when associated with their specific product, rather than green tea more generally.
Matcha in particular also has high levels of L-Theanine, an amino acid particular to tea which is boosted by the screening of the tea bushes for two to three weeks before picking. This is another component of green tea about which health claims have been made, although there is not yet a clear evidence-base for this. In fact, in 2011, EFSA produced a very in-depth scientific opinion to the effect that none of the alleged health benefits of L- theanine – including alleviating psychological stress, reducing menstrual symptoms, and improving sleep and brain function – had been proved. So health claims cannot legally be made about these issues in the EU.
So it seems – and the UK NHS agrees – that green tea will increase the amount of some specific nutrients in your diet and can contribute towards you consuming recommended daily amounts of particular nutrients. Also, a review in 2015 found that daily green tea consumption was significantly linked to a lower risk of death from any cause, including cancers and cardiovascular disease. The reviewers suggested that increasing green tea consumption by one cup per day was linked with a 4% lower risk of death from any cause. (Of course we all have to die of something sometime, but my understanding of this was that they had concluded that is reduced the risk of dieases such as cancer getting you before your time).
Traditional Chinese medicine has regarded green tea as a ‘health’ drink since ancient times and in Japan and across the world it’s become increasingly believed to the present day to have health-promoting properties. To check this out for myself, I looked at some systematic reviews of scientific research (see here for a very brief explanation of what systematic reviews are and why I prefer them).
Systematic reviews in 2002 and 2006 were conducted on the basis of mixed evidence that tea, being an important dietary source of flavanols, might help reduce the development of several chronic diseases, especially cardiovascular (heart) disease and cancer. The reviews concluded that green tea was associated with a moderate reduction in the risk of some chronic diseases. Its content of some vitamins and minerals increased its antioxidant potential and all the scientific research on green tea was found to be very promising. But the reviews concluded that future studies were necessary to fully understand green tea’s contribution to human health, and before advising its regular consumption in Western diets (whereas it is already a significant component of many diets in the East).
Several reviews since then have looked at green tea’s potential affects on specific health conditions, so now let’s have a look at some them.
The caffeine and catechins in green tea are considered to speed up your metabolism to increase your energy expenditure and burn calories quicker – so many people believe that green tea may contribute to weight loss. The many, many green tea products sold which make claims as a weight loss aid, are usually extracts of green tea containing a higher concentration of catechins and caffeine than a typical drink prepared by brewing a tea bag – although they may not contain more than a cup of matcha, depending on the formulation.
In 2012 a scientific review team pooled the results of 18 previous scientific studies, from Japan and elsewhere, that had looked at green tea’s potential weight loss and weight maintenance effects on a total of 1,945 adults. The review was conducted by the Cochrane Foundation, which has a very high reputation internationally as an organisation producing high quality and unbiased reviews of vast amounts of scientific research, and pooling the results and critically assessing what they tell us overall on a particular topic.
For people who put faith in green tea to boost weight loss, I’m afraid the results were disappointing. The reviewers concluded that green tea had no significant effect on the maintenance of weight loss and appeared to induce only a very small amount of weight loss, and/or reduction in body mass index and/or waist circumference, in overweight or obese adults. And remember that here, the reviewers were looking at studies of green tea extract supplements, which have higher levels, than a cup of tea made from a teabag, of what have been thought to be the active compounds for weight loss.
A systematic review in 2014 looked into whether regular consumption of green tea or green tea extract could improve insulin sensitivity in people at risk of type 2 diabetes. It looked at seven studies conducted up to December 2011 involving 510 participants, but again the results showed no positive statistically significant impact from green tea. Another review in 2016 of ten previous trials involving 608 people looked at the effects of all tea or tea extracts on patients already with type 2 diabetes. It was more promising, in that it found that they could maintain stable fasting blood insulin levels and reduced waist circumference in people who already had type 2 diabetes. But the effects on other outcomes – such as improving their cholesterol or body mass index – were not significant.
Another (Cochrane) review in 2013 assessed the effectiveness on all these health issues of green tea, black tea or black/green tea extracts in healthy adults and those at high risk of cardiovascular (heart) disease. The results showed both green and black tea to have a beneficial effect on cholesterol – on lowering total cholesterol in the case of green tea and on lowering LDL (‘bad’) cholesterol in the case of black tea. And both were shown to lower blood pressure. But the reviewers noted that the results were based on only a few trials that were at risk of bias. Due to the small number of trials contributing to each analysis, they said their results needed to be treated with caution until further high quality trials with longer-term follow-up might confirm the findings.
Another review in 2014, which pooled results in 13 studies produced between 1995 and 2013, also found that green tea and its catechins may improve blood pressure and may improve total and LDL (‘bad’) cholesterol.
The Cochrane Foundation conducted a large review in 2009 into the claims that green tea catechins may inhibit cells reproducing rapidly and therefore help prevent cancer. The review assessed the results of 51 previous studies which had been published up until January 2009 and had involved a massive 1.6 million participants. 27 studies had tried to establish an association between green tea consumption and cancer of the digestive tract; five with breast cancer; five with prostate cancer; three with lung cancer; two with ovarian cancer; two with urinary bladder cancer; one with oral cancer; and three others had included patients with various cancer diagnoses.
The results they found were mixed – being ‘highly contradictory’ for digestive tract cancer; ‘limited’ for liver cancer; and ‘conflicting’ for oesophageal, gastric, colon, rectum, and pancreatic cancer. There was a suggested decreased risk for prostate cancer in men consuming higher quantities of green tea or green tea extracts. But there was only limited to moderate evidence that they reduced the risk of lung and bladder cancer, and for the latter it was even suggested that they might increase the risk. There was also moderate to strong evidence that green tea consumption does not decrease the risk of dying from gastric cancer. There was limited moderate to strong evidence for a positive effect on lung, pancreatic and colorectal cancer.
The reviewers concluded, overall, that there was insufficient and conflicting evidence to give any firm recommendations about the consumption of green tea for cancer prevention, and that the results of their review should be interpreted with caution, as the majority of studies included had been carried out in Asia (47 out of 51) where the tea drinking culture is massive.
A review as recent as February 2017 looked at the results of 68 studies which had been published between 1999 and 2016 about a possible relationship between green tea and breast cancer prevention. The reviewers concluded that, while more clinical trials were needed to prove green tea impact decisively, nevertheless it was looking highly promising that increased green tea consumption could lower the risk of developing breast cancer. Overall, it seemed that the properties of green tea catechins could prevent and treat breast cancer, including by inhibiting the proliferation of breast cancer cells and blocking carcinogenesis (that is, normal cells changing into cancer cells), by adjusting the way cells communicate with each other in some bodily systems. They also found that green tea was proving extremely useful in the development of new anticancer medicines.
Can green tea prevent tooth decay?
A small study in 2014 (i.e. not a review, so we should treat its results with a little more caution) suggested that using green tea as a mouthwash including green tea was just as effective in preventing tooth decay as chlorhexidine, a commonly used shop bought antibacterial mouthwash. And green tea used as a mouthwash has the added advantage of being cheaper than mouthwash bought cover the counter.
It’s extremely unlikely if drunk in moderation, seems to be the answer. Apart from the obvious debate about the impact of caffeine, there have also been some concerns about incidences of hepatotoxicity (chemically-driven liver damage) potentially being linked to green tea consumption. However a Japanese review in 2013 found that, from the 34 previous trials that they examined, adverse liver impacts after taking green tea extracts were likely to be very rare.
The large Cochrane review from 2009 that I’ve already mentioned above, into links between green tea and various types of cancer, suggested that desirable green tea intake was between 3 to 5 cups per day (up to 1200 ml/day), providing a minimum of 250 mg/day catechins. The reviewers concluded that if people who enjoyed a cup of green tea were not exceeding the daily recommended allowance, then they should continue to do so without any safety concerns.
If you want to buy good quality matcha or other Japanese tea in beautiful Japanese tins, then one of the best traditional companies to purchase it from is Ippodo, which has existed for over 300 years in Uji, in Kyoto. Their online shop available in English includes lots of advice about which type of tea product to choose to suit your tastes, and they also sell all the accessories and starter kits which might make neat presents. Good quality mactha is also available in many health food shops nationwide in the UK, and in London, in the fantastic foodie Borough Market, and in the Japan Centre.
Traditionally matcha is prepared using the special utensils shown below. While they’re lovely to have, and they lend a sense of history and ceremony to matcha prepared at home, of course its completely unnecessary to go to the expense and effort of acquiring special kit, and for very similar results you can improvise with whatever spoons, whisks, bowls and cups you already have.
- Measure out around 1½ heaped chashaku bamboo spoons of powder (around 2g or 1 scant tsp) into a matcha-chawan (tea bowl).
Add about 60ml (1/3 of a tea bowl or 2fl oz) of boiling water cooled to roughly 80°C by pouring it into an empty teacup before putting it into the tea bowl.
Mix the matcha powder and water together until frothy with a chasen bamboo whisk using a quick backwards and forwards motion.
When the mixture is smooth, drink the matcha direct from the tea bowl. Though they are finely ground, the matcha particles will not actually dissolve, but they become suspended in the water by the whisking action. So to enjoy it at it’s finest and get all that green tea goodness, it’s best to drink it while it’s still frothy, and before the particles settle to the bottom.
If you fancy iced matcha as a on-the-go refresher, a convenient and quicker way to prepare it is in a shaker bottle, like those for protein shakes with a ball whisk included, or a sieve built in to the lid.
- Sift into the shaker around ½ tsp (1g) of matcha powder for every 100ml of liquid you intend to use (you don’t have to sift it if you’re really in a rush, but obviously it breaks up any clumps so that it mixes better with the water).
Add chilled water or your favourite milk in the corresponding quantity i.e. 100ml per ½ tsp of powder
Close lid and shake until well mixed.
Sweeten to taste, and you’re ready to take the bottle out with you. Make sure to shake it again to remix before drinking.
Several people have said to me that they don’t like the taste of matcha much. I’m not surprised about that, at least initially, as it really does taste much stronger and more ‘grassy’ than green tea made from a tea bag, and is quite a different drink altogether. I really like it now, but it certainly took me a few attempts to get used to it.
My tip is that if you wish to acquire a taste for matcha, then a matcha latte is a good entry level way of building up to that. These are served throughout Japan in coffee bars such as Doutor, the Japanese sort of homegrown equivalent of Starbucks. I really enjoyed the smooth and sweet Uji Matcha Latte that I had in Doutor at Tokyo station while waiting to board the bullet train to Kyoto.
Instant matcha latte powder sticks are also very easily bought in Japanese supermarkets and the 7-11 shops which seem to be on every street in big cities. As you might expect, they produce a drink that is frothy, creamy and sweet. The ones I saw seemed to have a controlled amount of calories and carbs that is certainly substantially less than in Doutor’s green tea lattes, or the ones I see that Starbucks are now selling in the UK.
To make your own matcha latte at home without all this processed stuff, simply whisk a scant teaspoon (about 2g) of matcha powder into a 200ml mug of your favourite hot milk (I use unsweetened almond milk), preferably with a handheld milk frother or stick blender. Making your own at home has the benefit of allowing you to decide for yourself whether or not to sweeten it, by how much, and with what (I prefer lower calorie/carb xylitol in most things that I feel need sweetening – see my full post about this natural alternative to sugar).
You’ll find recipes including matcha as an ingredient all over the internet. They are mostly for sweet dishes, although there are a few savoury ones too. You can experiment yourself with adding matcha to homemade muffins, biscuits, cakes or ice cream for flavour, colour and a nutrient boost. Or try dusting it on yogurt, trifles or other creamy-topped desserts, or adding it to smoothies, soups or tempura batter.
Affogato is one of my absolute favourite Italian desserts, and its very simple. If you’re not already familiar with it, then essentially it’s made by pouring a shot of hot espresso coffee over a scoop or two of good quality vanilla ice cream. Then eat it straight away! It’s perfect when I fancy something sweet after a meal, but want to keep it small and not overly sweet.
I experimented by making an alternative version, swapping a similar sized cup of hot matcha for the single espresso coffee in the traditional recipe to pour over the ice cream. As in the traditional version, the hot liquiid melted the ice cream a little so that it started mixing with the matcha, both cooling it down and making it beautifully creamy and sweet. It tasted great, and I found the umami flavour of the matcha made a more subtle contrast to the sweetness and vanilla in the ice cream, than the richer coffee flavours usually do.
I’m really looking forward now to trying out more recipes using matcha, and in future I’ll put up a related post including them and the results. In the meantime, it would be fab to hear about any of your own recipes in the comments!