What are the benefits of drinking green tea? People often ask this question, and no wonder! Used medicinally for centuries and touted today as a superfood, green tea has quite a reputation.
For us, the foremost benefit of drinking green tea is in the moment itself. The act of preparing and deeply appreciating a reviving cup of green tea is a small self-care ritual. We think there’s no better way to quieten the mind and connect with the present. But enjoyment is only one of the reasons green tea is held in high esteem.
Today, the once ancient Chinese remedy appears regularly in scientific journals, thanks to its bioactive compounds and related health benefits.
Join us as we learn about this verdant infusion and explore just how it packs so much power.
What is green tea?
Very simply: steep green tea leaves in hot water and you’ll have green tea. The qualities of the drink depend on a number of factors, such as brewing time and water purity; none so important as the tea leaves themselves.
Green tea leaves, like black tea leaves, are from the Camellia sinensis shrub. In fact all ‘true’ teas – green, black, oolong, pu’er and white – are made with the leaves of this one plant.
Differences between these are mainly down to what happens to the Camellia sinensis leaves once plucked.
For four of the five true teas, the harvested leaves undergo at least some oxidisation. This is a natural reaction between chemicals in the leaves that causes browning – just like in a slice of avocado exposed to the air. What distinguishes green tea from all the other true teas is that this process is stopped very soon after harvesting.
The processing of green tea
Green tea leaves are usually plucked early in the day and carried in baskets or cloth to prevent crushing. After brief withering, tea artisans heat the leaves using one of a range of traditional methods, such as pan-firing, baking and steaming. This quick heating prevents the leaves oxidising, preserving their green colour and keeping lots of soluble compounds intact.
These soluble compounds are responsible for green tea’s taste and its healthful properties.
Other influences on tea
Other factors that produce differences between teas (between and within true tea categories) include:
- country of origin
- variety or cultivar of Camellia sinensis,
- leaf type (from buds to larger leaves),
- growing conditions (e.g., shaded or not),
- time of harvest,
- processing methods.
So, green tea is actually quite a general term that comprises teas with variations across all these factors.
Ancient origins and benefits of green tea
Humans have been drinking tea for centuries. Legend has it that Chinese Emperor Shennong discovered green tea in 2737 B.C. when a dead leaf blew into his boiling water. The drink slowly gained popularity and notoriety for its healing properties. It first shows up as a remedy in records from the Shang dynasty (1766 – 1050 B.C.)1.
By the time of the Tang dynasty, green tea was considered medicine. Xin Xiu Ben Cao (the first book of drugs and their uses) drank green tea and recorded its benefits, including:
“pushing down rising qi; eliminating thirst, heat and phlegm; diuretic, shortening sleeping time”2.
Scholar Li Shizhen of the 16th century wrote that:
“Tea is cold and lowers the fire [inflammation]”3.
While science and medicine have moved on since these observations, it’s striking that they are recognisable in green tea’s studied benefits today.
Types of green tea
As we’ve alluded to, there are countless types of green tea. Growers in China, Japan, Kenya and beyond produce distinctive teas using a variety of traditional methods. Here are just a few:
One of China’s most famous leaf teas. Grown in the Hangzhou mountains, gathered for a few weeks in early spring and processed by hand. A clear green tea, with a bright and fresh taste.
From Zhejiang province, China, and named for the style of its roll: fine pellets that resemble gunpowder. It’s usually tumble-fired and produces a clear olivey-green tea with a robust, slightly smokey taste.
This is the most popular green tea in Japan. Sencha leaves are steamed or baked and the resulting tea is deep green with a vegetal, grassy flavour.
Distinct from other green teas, because the drinker consumes the powdered leaves. Matcha powder is also from Japan – from the Uji region, made from shade-grown leaves. The drink has a strong ‘green’ taste.
What does it taste like?
Because of the variation between types, it’s impossible to describe a single flavour profile of green tea. People often think of green tea as grassy or ‘green’ tasting, but it can be light and delicate, strong and astringent, floral and earthy, vegetal and roasty, or any combination of the above - depending on the type.
Our popular Pure Mountain Green Tea from the hills of southern China is light and smooth. On the other hand, our Mao Feng loose leaf green tea is fresh and intriguingly complex, with hints of peach.
Properties and benefits of green tea
Green tea contains a number of compounds that naturally occur in Camellia sinensis. These influence the taste of the tea, and they can also have effects in the human body.
They include caffeine, amino acids (such as L-theanine) and a range of polyphenols, (including cathechins, such as epigallocatechin). Polyphenols can act as antioxidants in the body: reducing harmful free radicals and protecting cells from damage. This antioxidant power is thought to underpin many of the benefits of green tea.
Literature exploring the properties of green tea is vast and ever-growing. Here we’ll explore seven of the most-studied health benefits.
1. Brain function
Green tea contains moderate concentrations of caffeine, well-known for keeping us awake and alert. Studies show that in moderate doses, caffeine may also improve brain functions, such as mood and reaction times4.
Green tea also contains the amino acid, L-theanine. This compound can have anti-anxiety effects by increasing GABA activity, dopamine production and alpha-waves. Studies suggest that the combination of caffeine and L-theanine is especially potent, and can improve brain function, particularly attention and focus5.
Some research suggests green tea can affect how quickly we convert food and fat to energy. Studies have shown green tea extract can increase energy expenditure and ‘fat burning’ in the short term6. Caffeine is thought to be partly responsible, but scientists think the combination with catechins accounts for green tea’s unique effects on metabolism7.
Studies that indicate green tea can aid weight loss support the notion it can boost metabolism. For example, one trial found that green tea-consumers had significant belly fat- and weight-loss compared to the control group8. Another experiment showed the catechin, epicatechin-3 gallate (EGCG), might be responsible for these ‘fat burning’ effects9.
However, research on the effect of green tea on metabolism has mixed results, so further robust studies are needed to confirm this potential benefit.
Research on green tea’s anti-cancer effects focuses on its polyphenols. These may inhibit the growth of cancerous cells due to their demonstrable influence on cancer processes and factors.
While promising literature links consumption of green tea with the reduced risk of many types of cancer, including prostate, colorectal, bladder and breast cancer, other studies do not confirm the association10.
This field of important research therefore continues to investigate green tea’s anti-cancer effects.
Neurodegenerative diseases such as Alzheimer’s Diseases (AD) and Parkinson’s Disease (PD) involve loss of cognitive function due to break down of brain cells and structures. Because of its benefits for cognitive function, scientists are interested in green tea’s impact on these diseases.
Findings show that green tea can indeed lower risk of developing PD11. Other research focusing on ECGC suggests the polyphenol is neuroprotective because of its antioxidant effect, and that green tea can therefore help protect against dementia and neurodegenerative diseases12.
Diabetes is a condition that affects how the body converts food into energy. People with type 2 diabetes either don’t make enough insulin, or their insulin doesn’t work as it should, resulting in elevated blood sugar levels.
Research suggests that ECGC from green tea can mimic insulin, facilitating uptake of glucose into the cells and decreasing glucose production13. Another study identified a protein that might also be involved in this antidiabetic effect14. Whatever the mechanism, it seems green tea has a positive effect on diabetes: a large review suggests drinking more than 4 cups of green tea a day may lower risk of type 2 diabetes15.
Nevertheless, medical advice emphasizes that green tea should be part of a balanced, low-sugar diet and never used as a replacement for prescribed treatment.
6. Cardiovascular disease
Green tea consumption may be good for heart health due to its protective effect against cardiovascular diseases (CVD), such as heart disease and stroke. Studies suggest that drinking green tea is negatively associated with risk of death from these diseases16. This might be because green tea reduces both LDL (undesirable) cholesterol and total cholesterol levels17. It also protects LDL against oxidation, which is a risk factor for CVD18.
Green tea’s catechin EGCG may help fight coronaviruses, including COVID-19. Studies have found EGCG inhibits the enzyme action of the main coronavirus protein and may suppress the virus’s ability to replicate. Alongside other protective measures, drinking green tea could therefore help protect against these coronaviruses19.
What is green tea good for?
Whether you look to Traditional Chinese Medicine, modern science or simply the calming effect you experience when drinking it, it’s fair to say green tea is great as part of a healthy lifestyle.
Given the potential green tea benefits listed above, it stands to reason that green tea may also be good for longevity! Large-scale, longitudinal Japanese studies found that regular green tea drinkers were significantly less likely to die during the research period20.
Side effects of green tea
Green tea’s health benefits show that it can have powerful effects on the body. These effects are overwhelmingly positive, but it’s prudent to be aware of how green tea can interact with other conditions.
We always recommend checking out your tea with a doctor if you’re pregnant, breastfeeding or taking medication.
Here’s our FAQ about green tea’s side effects.
Are there calories in green tea?
Any calories in a cup of green tea come from added sweeteners (and milk in the cases of matcha latte). We think green tea is best appreciated plain, when it also happens to be calorie-free.
What about aluminium and iron?
Camellia sinensis can accumulate aluminium, a natural element that is essential for root growth. Overconsumption of any true tea can therefore lead to the accumulation of aluminium in the body. Patients with kidney issues should therefore check with their doctors about controlling their tea intake.
Studies suggest the polyphenols in green tea may bind to iron, making it less bioavailable21. People with anaemia should therefore limit the number of cups of green tea they drink per day.
Does green tea have caffeine?
Camellia sinensis leaves all contain some naturally occurring caffeine. The amount of caffeine in each type - and even each cup - of tea can vary. This depends on a number of factors, from leaf type to water temperature and steeping time.
Generally speaking, a cup of brewed green tea has less caffeine than a cup of black tea, and between a quarter and a third of the amount of caffeine in a cup of brewed coffee22.
You can control the amount of caffeine in your cup by using hot rather than boiling water (let the kettle cool for four or five minutes before pouring over your teabag or tea leaves) and keeping the brewing time brief (two to four minutes). These measures release less caffeine and also avoid scalding the leaves, which negatively affects the flavour profile.
Too much caffeine can leave us jittery, anxious and unable to sleep. However, as discussed above, moderate amounts of caffeine can be considered beneficial to the mind and body. A maximum of 400mg of caffeine – approximately eight cups of green tea – is recommended to maximise the benefits of caffeine and minimise the risk of its side effects23.
There are some decaffeinated versions of green tea available, but caffeine can never be fully removed. If you’re avoiding caffeine altogether, many herbal teas are naturally caffeine free.
How does green tea compare to other teas?
Green tea vs black tea
Both teas come from Camellia sinensis and like green tea, black tea comprises a range of types with different origins, production methods and flavour profiles - from delicate Darjeelings to rich Assams.
Unlike green teas, black tea leaves are withered and bruised or gently ground to promote full oxidisation. This gives them their dark colour and full bodied flavour with malted notes, while green tea leaves retain their colour and vegetal taste.
Both green and black teas contain polyphenols from the Camellia sinensis plant, but these are reduced in black tea. Green tea contains significantly higher levels of the catechin EGCG – key in many of its health benefits.
Green tea vs white tea
White tea also comes from Camellia sinensis, but while green tea describes a range of teas, white tea is a specific designation. White tea leaves come exclusively from the Chinese Fujian province, must be plucked as buds and are minimally processed. While oxidation of green tea leaves is quickly cut short by heating, white tea gently oxidises as it dries; and unlike green tea, the leaves are never rolled.
Both teas can have nutty and sweet notes, but green tea can also have a bittersweetness, while white tea is free of bitterness. Green tea is often more complex tasting, with vegetal and floral flavours while white tea tends to be delicate and light.
Green tea vs rooibos tea
Rooibos comes from a different plant to green tea and the other true teas: the Aspalathus linearis shrub. It is naturally caffeine free with a clear, ruby red colour and honeyed sweetness, quite unlike the grassy, sometimes marine notes of green tea. While also celebrated for its healthful properties, rooibos has different active compounds than green tea, namely aspalathin and nothofagin.
How to drink green tea
In order to experience the wellbeing as well as the potential health benefits of green tea, we recommend a little tea mindfulness.
Follow the brewing instructions on your pack of Dragonfly green tea for the perfect cup. Always remember to let your kettle cool a little before you pour the water over your teabag or leaves so as to avoid scalding the leaves and damaging the catechins! If you need to stock up, find our range of loose leaf green teas and green teabags right here.
- Heiss, Mary Lou & Heiss, Robert J, 2007, The Story of Tea, Ten Speed Press.