Green Tea has been around for centuries but has gained attention more recently for its alleged health benefits. People all over are making claims about the anti-inflammatory, antioxidant, cancer-fighting properties and weight loss benefits to be reaped from drinking green tea.
In this article, you can expect to learn more about the history of green tea, the difference between polyphenols and flavonoids, what in the world catechins are, the powerhouse duo that is L-Theanine and caffeine, and the most important part of green tea, epigallocatechin gallate, or EGCG.
You’re also going to learn what claims people are making about green tea are true, and those that are merely exaggerations. Before we get into any of this, however, let’s take a look at the history of green tea.
A History of (Green) Tea
Green tea was said to be discovered in 2737 BC when Chinese Emperor Shennong was resting on a roadside when a tea leaf from a nearby bush fell into his cup of hot water. It’s fabled that Shennong found the drink favorable, and had members of his convoy prepare it for him henceforth.
Other accounts place the origins of tea during the Shang Dynasty in China between 1500-1046 BC, stating that it was consumed as a beverage for its medicinal properties.
It is unclear what the actual origin of green tea really is, as Shennong is a popular figure of Chinese mythology, though there is no doubt that it is one of the earliest documented drinks in existence. It has played an important role in Asian culture for centuries, if not millennia.
Up until around 200 AD, tea had actually been used more commonly in rice dishes, and instead of brewing it to drink, the Chinese were adding things like ginger, scallions and tangerine peels. It was during this time that tea became more of a status symbol, with rare kinds being brought to leaders and rulers as gifts. Trading in tea started to become a commercial activity.
By the end of the 3rd century, the number one beverage in China was tea. Today, it is second only to water worldwide.
Around the time of the 5th century, tea ceremonies were becoming popular in China. In 600 AD, Lu Yu wrote the book Cha Jing, or Tea Classic. The book detailed current and traditional Chinese tea culture and proper serving methods.
It was also around this time that the Tang Dynasty saw tea trees planted all over the country, which resulted in traveling monks returning with seeds to their home countries, expanding the cultivation of the crop to other countries.
Up until the 8th century, green tea drinkers hadn’t been treating their tea leaves before steeping. This was around the time that steaming tea leaves was found to halt the oxidation process, helping the leaves retain their natural green color.
By now, the Chinese have already begun trading tea to Tibet, the Arabs, the Turks and along the silk road to India.
Around 1300 AD, machine-made tea was being produced, though commoners still mostly used loose leaf in their daily cups.
In the 16th century, tea, the most stereotypically British drink, first made it to European soil by way of Holland before taking another 100 years to actually reach England.
The next innovation came later in the 18th century when Japanese tea masters introduced mechanical methods for “fixing the green” which simply made the steaming, and by this time, the baking and roasting of the leaves more streamlined. For the most part nowadays, green tea is steamed or pan-fried to fix the color.
Steaming the leaves actually became necessary to retain freshness when shipping tea long distances to Europe. The darker color of the leaves became known as black tea, which is why geographically, the Chinese love green tea and Europeans prefer black tea.
Interestingly enough, the sale of tea in England and by extension, the colonies, was taxed so heavily and was so expensive that it gave birth to large-scale smuggling operations. With smugglers selling tea for less than half of the ‘official channels’, 70% of tea consumed in England was contraband as well as close to 90% of that which was consumed in the colonies.
At one point, 35% of the currency flowing through the Bank of England was tea trade related.
During the Qing Dynasty (1636 – 1911), many varieties of tea were both popular and available, such as Yellow, Oolong, Green, White, Dark, Black and Flower Tea. The crazy thing is, they all came from the exact same plant native to China, Camellia sinensis.
A Look at the Structure of Green Tea
Now that we’ve gotten through the history of tea, we’re going to delve into the make-up of green tea to gain a better understanding of what makes it so special.
While it is true that green tea does not contain a significant amount of caffeine, it doesn’t change the fact that caffeine is the most common stimulant in the world. Caffeine has been shown to stimulate the central nervous system in ways that make us more alert and increase our reaction time.
With less caffeine than a cup of coffee, a mere 20-60 mg compared to the 100-300 mg average of coffee, green tea isn’t exactly the go-to beverage when we’re trying to get our morning routine started. Still, if you’re looking to stay well-under the 400 mg recommendation for daily caffeine intake, or are sensitive to the high amounts of caffeine in coffee or soda, green tea might be the better option.
It is believed that caffeine blocks a neurotransmitter called adenosine. Adenosine is a chemical in the body which is believed to contribute to drowsiness as adenosine levels rise throughout the day. Studies have shown that caffeine blocks certain synapses in the brain from receiving adenosine, which prevents the buildup of the ‘sleep pressure’ that adenosine contributes to.
While coffee may be a better bet for keeping you up during the long hours or helping you get out of bed in the morning, the real magic of green tea comes from a combination of caffeine with an important amino acid…
L-theanine is an amino acid found in green tea. L-theanine has been shown to reduce stress and lower heart rates by inhibiting neuron excitation in the brain, and is suggested to improve cognition and mood in humans.
When combined with the low levels of caffeine in green tea, however, studies have seen an increase in the generation of Alpha waves in brain activity. L-Theanine is not present in coffee, but in green tea it acts to stunt the effects of caffeine, resulting in improved brain function in favor of pure caffeine side-effects.
Theanine also affects the secretions of serotonin, epinephrine, norepinephrine, and GABA, which all lead to a relaxed and calmer state of mind, which could lend itself to the argument that green tea helps combat depression and anxiety.
Polyphenols are a class of chemical compounds found in plants. There are over 8,000 known polyphenolic compounds, most of which have strong antioxidant capabilities, and go so far as to neutralize free radicals, reduce inflammation and slow tumor cell growth.
Examples of polyphenols in other foods would be capsaicin in paprika, cinnamic acid in cinnamon, resveratrol in red wine and curcumin in turmeric.
Polyphenols help lower cholesterol, lower blood pressure, improve artery function, prevent platelet clumping, improve arterial flexibility and improve life expectancy.
Polyphenols are the main driver of the antioxidant content of green tea, and polyphenols themselves are separated into four distinct groups:
Stilbenes, Lignans, Phenolic Acids, and Flavonoids, with flavonoids being the most prominent type of polyphenol found in green tea leaves.
Flavonoids are a type of phytonutrient which is mostly responsible for the vivid colors seen in fruits and vegetables. Flavonoids have both strong antioxidant and anti-inflammatory properties themselves, and can be further divided into six subclasses:
Anthocyanidins, Flavan-3-ols (Flavanols), Flavones, Flavanones, Isoflavones, and Flavonols, which are distinctly different from Flavanols.
The main sub-group we’ll focus on is the Flavanols, and while this group is diverse and can be broken down into things like theaflavins and thearubigins found in black tea, we’re only interested in the monomer class, better known as Catechins.
A catechin is a type of flavonol, and there are six types of catechins present in green tea:
C, EC, GC, ECG, EGC, and most importantly, EGCG, or epigallocatechin gallate.
EGCG is arguably the most important catechin in green tea, and is the focus of nearly every major study which observes the health benefits of green tea. If you read a tea label and it claims that the polyphenol content is about 300mg, all you really need to know is that’s the antioxidant content of your tea, and those polyphenols are mostly made up of catechins.
The average polyphenol content of green tea is about 30% of the dry weight of the tea. 30% of a gram of dry tea gives us our 300mg polyphenol content.
It’s also important to note that green tea has a higher catechin content than Black Tea because catechins are unoxidized, and when black tea is made, catechins oxidize to form thearubigins and theaflavins.
Theaflavins are powerful antioxidants, just like catechins, but where green tea contains around 30% catechins, black tea contains a mere 4% theaflavin content. Green tea has a much higher quantity of antioxidants, making it the more beneficial option.
EGCG in green tea is really what’s mostly responsible for any of the perceived and documented benefits that green tea claims to offer. Green tea has been touted as a preventative measure for many such ailments as diabetes, atherosclerosis, cardiovascular disease, cancer, diabetes, halitosis, depression, IBS, Parkinson’s, Alzheimer’s, HPV, the common cold, and Athlete’s Foot.
It has also been said that drinking green tea boosts metabolism, helping with weight loss and lowering bad cholesterol. With this many claims being made about the magical properties of this ancient beverage, we have to ask:
Just how much of it is true?
Green Tea and Health
Cardiovascular Disease, Blood Pressure and Cholesterol
In trials targeted towards lowering total cholesterol, LDL cholesterol, and blood pressure, green tea produced statistically significant results.
It was also found that in laboratory mice, the catechins in green tea, especially EGCG, were shown to prevent the development of atherosclerosis, and actually reduced the progression of atherosclerotic plaque formation in the arteries.
In a study where obese, hypertensive patients were given green tea extract supplements for a period of 3 months, researchers found that daily supplementation “favorably influences blood pressure, insulin resistance, inflammation and oxidative stress.” It was also concluded that supplementation resulted in a decrease in LDL cholesterol and an increase in HDL cholesterol.
Between these three studies and countless others, we can draw the conclusion that since EGCG in green tea and green tea extract helps increase blood flow, lower unhealthy cholesterol, slows the progression of plaque buildup in the arteries AND acts as an anti-inflammatory, green tea is beneficial to heart health and is a sound long-term preventative measure to take against cardiovascular disease.
In a meta-analysis of fifteen studies including 1243 patients, researchers found that there was a statistically significant reduction in BMI, body weight, and waist circumference when participants ingested green tea catechins in combination with caffeine.
Oddly, the same results were not found when only catechins were administered. Once caffeine was introduced, which is the same combination of catechins and caffeine you’d be getting from simply drinking the tea, results were deemed significant.
Now, we shouldn’t confuse this with a miracle cure for weight loss. While it’s true that green tea appears to accelerate the metabolism and encourage weight loss, it is no substitute for a healthy diet and exercise, though it could be a beneficial addition to an existing routine to help burn even more fat.
Caffeine also seems to be an important factor in the ability of EGCG to help with weight loss so instead of banking on green tea supplements if weight loss is your goal, try incorporating a cup or two (or more) of green tea into your routine instead.
When looking at an issue such as depression, and especially, the role that green tea could play in reducing it, we have to rely on long-term geographic studies that can be skewed by an unknowable amount of factors.
Still, there have been multiple studies confirming a correlation between high rates of green tea consumption and lower prevalence of cognitive impairment.
A meta-analysis of 12 studies spanning from 2000-2016 revealed a statistically significant relation between tea consumption and depression symptoms among 629,910 total participants. Researchers found the risk of depression could be upwards of 35% lower among those who consumed green tea, and concluded that daily intake was a recommended preventative measure for combating depression.
There have been many studies done on the link between cancer cell growth and green tea consumption, with the majority being limited because they are geographic studies with moderate room for error.
Some studies have shown that in early stage breast cancer, green tea consumption may actually help prevent recurrence with an intake of three or more cups daily.
While another meta-analysis has come to a similar conclusion about the link between green tea and liver cancer, the National Cancer Institute claims their meta-analyses found inconclusive results, though a study is mentioned wherein cancer cell growth in vitro was stunted by the introduction of green tea catechins.
Whatever the case may be, there’s enough evidence to say that the catechins in green tea may very well have cancer-fighting properties, which means more studies must be conducted in the coming years in an attempt to get to the bottom of the issue.
In some studies, no evidence has been found to support the claim that supplementing your diet with green tea catechins helps slow, reverse or treat the symptoms of Type II Diabetes. In others, it has been found that catechins in green tea played a role in reducing waist size and managing obesity in diabetes patients.
Yet another study showed that green tea extract did not improve insulin resistance in diabetics, though it did show a correlation between green tea extract supplements and a decrease in waist circumference.
Oddly enough, one study did show that among those who regularly ingested caffeine via green tea and coffee saw a reduced risk for developing type II diabetes. This correlation suggests that the daily intake of green tea, or even coffee, could actually help lower one’s chances of developing diabetes, but does not help those who already have it.
Catechins from green tea have been shown to have an antibacterial effect on periodontopathic bacteria and even inhibited destruction of periodontal tissue in vitro. In a more creative study, researchers determined that a gel made from green tea catechins helped reduce gingival inflammation and bleeding.
How does this translate to drinking green tea, though? According to one study, a cup of green tea daily was actually associated with a higher risk of periodontal disease in Korean adults. This study did present the problem of being geography-based and therefore is ultimately inconclusive and ineffective at saying with certainty that drinking green tea is bad for your gums.
While drinking green tea may not necessarily be beneficial to gum health, another study not only corroborated the use of green tea gel to treat gum inflammation and bleeding, but found it was even more effective than a fluoride-based gel.
Halitosis, or bad breath, can also apparently be treated by green tea consumption. Research suggests that the powerful antioxidant effects of green tea help to reduce and combat bacteria in the oral cavity which, in turn, reduces oral afflictions. Further research is necessary to determine whether or not green tea could reduce chances of oral cancer in smokers.
Alzheimer’s and Parkinson’s Disease
In pre-clinical trials, EGCG has been reported to show promising results in treating the symptoms of Alzheimer’s. In vitro and in vivo, EGCG has been observed to exhibit anti-neuroinflammatory properties and inhibits the accumulation of amyloid peptides: the main component of plaques found in the brains of Alzheimer’s patients.
Another study found that patients taking green tea supplements showed improvement in cognitive function after just two months.
While using green tea extract to treat Alzheimer’s and Parkinson’s may not be the most effective option, there’s a good amount of evidence suggesting that the neuroprotective properties of the catechins in green tea could help prevent neurodegenerative diseases.
A meta-analysis of fourteen studies spanning 513,804 participants revealed that drinking three or more cups of green tea daily resulted in a 13% decrease in the risk of stroke.
It was also found that in test rats given green tea supplements after induced strokes, the supplements played a neuroprotective role and may even have a beneficial effect on post-stroke cognitive function.
In a study of 51 patients with HPV infected cervical lesions, patients were divided into four treatment groups and compared with an untreated control group.
The groups were treated with a green tea derived ointment, EGCG capsules or a combination of the two. A 69% response rate was achieved in comparison to the 10% control group response rate and revealed green tea extracts to be a potential therapy regimen for those affected by HPV.
Surprisingly, the antioxidant and antiviral properties of EGCG in green tea can go so far as to inhibit the infectivity of both influenzas A and B.
In a lab study of cells in vitro, an electron microscope revealed that EGCG binds to the virus and prevents it from being absorbed into cells. Another study found that among participants taking green tea extract capsules, there were 32.1% fewer subjects with symptoms, 22.9% fewer illnesses and 35.6% fewer symptom days than those in the placebo group.
While these studies involved EGCG capsules and did not have participants simply drink green tea daily to note the effects, these conclusions lend themselves to the idea that drinking green tea high in catechins daily could keep influenza and its symptoms at bay.
As far as we could find, there have been no clinical trials on the use of green tea to treat athlete’s foot, but that doesn’t mean we’re ruling it out as a possibility.
Green tea ointments have been used to treat dry, irritated and itchy skin for some time with soothing results, so while a green tea salve may not get rid of Athlete’s foot, it does stand a good chance at reducing the pain and inflammation it brings with it.
Basically, It’s Good For You
While some studies on the more far-fetched claims of green tea have been inconclusive, there are no doubts that the anti-inflammatory, antibacterial, antiviral, anti-carcinogenic, and antioxidant properties of green tea have numerous and far-reaching health benefits.
Most of the studies that look at the consumption of green tea in its basic form, that is, not as an extract, capsule or ointment of some sort, recommend 3-5 cups a day for maximum benefits, though it is important to note that all of that caffeine does add up.
Like we mentioned earlier though, the caffeine comes with L-theanine in tow to help mellow out the jitters, so it may not matter all that much in the end.
What’s the Word on Matcha?
Matcha is a form of green tea that is grown using much more specialized methods. During the last few weeks of growth, an ordinary tea bush is covered and spends the rest of its growth cycle in the shade. When the bush is ready for harvest, women who know exactly what to look for will pick only the newest and youngest leaves from the tea bush.
These leaves are then ground into a very fine powder using a stone mill (never machined) before being sold as matcha. Ceremonial grade is the ideal form for making tea and sprinkling on top of other foods for more raw consumption. Culinary grade matcha is perfect for use in baking and other recipes, and is broken down into 5 more distinct grades.
There’s a figure floating around the internet stating that matcha contains 137 times the catechin content of green tea, but this number comes from a very limited study that only compares one type of matcha powder to one type of green tea sold by Starbucks.
While there’s no arguing that matcha is packed with more beneficial catechins than green tea, if it truly contained 137 times more catechins, it’d likely be toxic to humans. There are other figures floating around that claim one cup of matcha tea to be as nutrient-dense as anywhere from 3 to 10 cups of green tea, but we couldn’t find any research to back this up.
Matcha is a great addition to smoothies and baked goods, and has plenty of benefits to offer over green tea, and should really be considered the superfood version of green tea.
It has all of the same amazing benefits as green tea just packed tighter into a brilliant and vibrant green powder. Since you’re consuming the whole leaf instead of just water poured over it, you’re getting all of the phytonutrients and antioxidants that leaf has to offer.
Matcha is, however, considerably more expensive than green tea. It’s much cheaper to drink a few cups of green tea a day than a cup of matcha tea, though you absolutely could if you so choose.
You could also make a simple cup of matcha tea, though be warned, it tastes much stronger than regular green tea and some may find it to be on the offensive side. If you’re not used to the taste of spirulina or wheat grass, you may find it better to stick to green tea.
It is also worth noting that matcha has a higher caffeine content as well, though thanks to the proportional increase in L-theanine content, we still avoid the caffeine jitters usually seen in coffee consumption.
Just as a final tip, we would like to also point out that the matcha powder Starbucks uses is actually cut with sugar and is, therefore, less effective. Skip the line (and steep price tag) and buy in bulk or grab a bag at the local supermarket for the best results.
All-in-all, here’s what we’ve learned about green tea:
- It is a powerful antioxidant and anti-inflammatory
- It has anti-carcinogenic, cancer-fighting properties
- It has antiviral and antibacterial, disease and virus fighting properties
- It helps prevent heart disease and improves cognitive function in stroke victims
- It can be used to treat skin conditions and promotes healthy skin
- It can help prevent Type II Diabetes
- The catechins in green tea combine with the unique compound L-Theanine which results in an alert state that is simultaneously relaxed and not jittery like coffee
- It can help reduce stress and anxiety
- It can help prevent bad breath
I can only imagine that reading this list has been a long journey, and if you’re still with us, thank you for taking the time to learn about the health benefits this wonderful plant has to offer. As a treat, here’s a video to show you how to brew the perfect cup of tea: