Don Mei : Hey Teaheads.
This is Don from Mei Leaf.
In this video : Caffeine in tea - facts and myths.
In this video I'm going to be giving you all the information that you need about caffeine
in tea, and we're going to be debunking a few commonly told myths.
This video is going to go under the "Basic Tea Education" playlist.
If at any point in time you enjoy this video then please give [it] the thumbs-up.
The more thumbs in the air the more tea videos are going to come your way.
If you haven't subscribed to our YouTube channel yet then go click that button.
We are in Koh Samet, a couple of hours drive away from Bangkok.
We managed to steal away a few days holiday, but the videos must go on, and so I thought
today we would have a little tour around the island, and I would be giving you as much
knowledge as I possibly can about caffeine in tea.
This is one of the most requested videos, so I thought it was about time to get this
knowledge over to you.
One quick disclaimer [I have is that] the information I'm going to give you is based
on the latest studies that I've found.
I'll put links [to] the studies in the description below, but this is an area which is continuously
changing.
There are no hard and fast rules, and the area is very, very complex.
If you have any comments, [or] any other information, then please do share, and I will try to update
the description below.
Or if you're watching this on our Mei Leaf website then I'll put the information in the
blog post below.
Okay, let's go explore this beautiful island, and learn about caffeine in tea...
Firstly, what is caffeine, and what does it do?
Caffeine is, by far, the most widely consumed psychoactive drug in the world.
It exists naturally in over 60 plants - including the cocoa bean - but is most widely consumed
in coffee and in tea.
Caffeine is [in] a class of compound called Methylxanthines, and it is a stimulant.
Its primary stimulant effect is that it attaches to receptors in your brain that are reserved
for adenosine.
As you burn energy, in the form of ATP - or adenosine triphosphate - a byproduct is adenosine.
So, throughout the day, adenosine levels build up and [attach] to receptors in your brain,
and that leads to a feeling of sleepiness.
Because caffeine mimics the shape of adenosine it can attach to those receptors in place
of adenosine, and therefore it can relieve feelings of sleepiness.
Therefore, the beneficial effects are caffeine are : to increase cognitive abilities, to
relieve fatigue, [and] enhance performance and endurance.
The negative side effects of excessive intake of caffeine are: jitters, anxiety, elevated
blood pressure, and it can stiffen blood vessels.
So let's move to our first myth.
The first myth is that caffeine is always bad for you.
The fact is that moderate intake of caffeine can have a moderate protective effect against
certain diseases, such as : coronary heart disease, Parkinson's [disease], and some types
of cancer.
So it is not all bad news, as long as you keep your caffeine levels in check...
So, how much caffeine is too much caffeine?
Well, this is not so simple, because everybody metabolizes caffeine at a different rate,
and you can build up tolerance to caffeine if you drink more of it.
But general guidelines are [that] about 400 to 500 milligrams per day is a safe upper
daily limit.
If you're pregnant then that drops to about 150 to 200 milligrams per day.
For children, caffeine is not suitable for anyone under the age of four, and once you
go past the age of four then the calculation is about 1.0 milligram per 2.5 kilograms of
body weight.
Once an adult gets to about 1,000 milligrams per day then things start to get serious,
and at 10,000 milligrams it can be lethal.
I'll talk about how that relates to tea and coffee in a second, but let's debunk a myth
first.
There is a myth that tea is dehydrating, because caffeine is a diuretic.
Now, caffeine is a diuretic - in other words, it stimulates you to go and urinate - but
it's a mild diuretic, and the amount of water in tea and coffee vastly outweighs this diuretic
function, so tea is actually very hydrating [and] not dehydrating.
I hope we can finally put that myth to bed...
So, how much caffeine is in tea and coffee?
In coffee, an average espresso shot is about 70 to 80 milligrams of caffeine, and an average
cup of coffee is somewhere in the region of about 120 milligrams of caffeine.
Obviously there is variation above and below that.
So, in order to reach your 400 to 500 milligram daily maximum allowance you can't really be
drinking more than three or four cups of coffee.
Tea, as we will soon find out, is much more complicated to work out the caffeine content,
because of the variety of types, the way that it's processed, and the way that it's brewed.
But, as a general rule, an average cup of tea is between about 10 and 60 milligrams
of caffeine, so in order to reach your maximum daily allowance you're looking at something
in the region of eight cups of tea, even if it's the most strong in caffeine.
[The] effects of caffeine in tea and in coffee are different on the human body.
The primary reason for that is theanine.
Theanine is an amino acid which, pretty much, exclusively exists in tea.
It crosses the blood-brain barrier and affects your mood.
It's a very powerful psychoactive substance, [which] increases your feelings or relaxation,
[and] increases alpha brainwave activity which leads to a more meditative state.
[Studies] have shown that theanine - in combination with caffeine - acts synergistically to enhance
the positive aspects of caffeine - in other words, the improvement in cognitive awareness,
cognitive ability, and performance - but reduces the negative effects of caffeine, like anxiety
and jitteriness.
Also, studies have shown that EGCG and polyphenol contents in tea can modulate the effects of
caffeine.
It is thought that it does this by reducing, or slowing down, the uptake of caffeine.
Therefore, you get more of a time-released stimulant effect, versus drinking caffeine
in coffee, which has a very quick on and quick off [effect].
That means that it affects your nervous system more, and it means that you have an energy
dump, which leaves you craving another cup of coffee.
So whilst caffeine is the same in tea and in coffee it has markedly different effects.
[This] leads me to my next myth, and that is that tea does not contain caffeine, but
instead contains "tein" or "theine".
When caffeine was first discovered in tea it was called "theine", but it is exactly
the same molecule.
It is exactly the same chemical, so this myth that theine is different from caffeine is
simply not true.
Caffeine exists in both tea and in coffee, and they are identical...
So how much caffeine actually exists in the tea leaf?
About 1% to 5% of the weight of the tea leaf is caffeine, and this wide variation of 1%
to 5% really depends on a variety of factors that makes this area quite complex.
The tea plant makes caffeine because it is toxic to insects, so it protects the plant
against being bitten by insects.
It is produced in the [buds] and the very young leaves, because these are the parts
of the plant that are tender and soft and more likely to be bitten by insects.
So it is certainly true that if your tea comes from pickings of the buds and very first [leaves]
then it is more likely to have higher levels of caffeine, and as you move down the plant
lower leaves contain less caffeine.
Also, the season of when it's picked has an effect.
Summer means more insects, and so the plant produces more caffeine.
So summer-picked teas will have a tendency for higher caffeine compared the spring-picked
teas.
The variety of the tea plant makes a big difference too.
Assamica varieties will have higher caffeine content than Sinensis varieties, and Clonal
teas will have higher caffeine [as opposed to] seed-grown teas.
Also, if you shade-grow the teas - as in Japanese Giokuro [teas] and Tencha, to make Matcha,
then you increase the caffeine content.
Other than that, the processing of the tea plant, and the level of caffeine, is very,
very unclear.
There are some tentative studies that have been done that show that the longer you wither
the tea the higher the caffeine content, slightly.
There are some studies that show that if you oxidize the tea for longer [the] period of
oxidization may reduce the caffeine content slightly.
There are also some studies that show that roasting the tea may reduce caffeine content
slightly, although I have to say that these studies are very, very tentative, [and] very
small scale, and if you look at coffee, and how the roast doesn't actually affect the
caffeine content of coffee, I question those studies quite considerably.
[This] moves us on to our next myth.
Many tea sellers out there try to give you clients real hard and fast rules by saying
[things like], "White tea has the lowest amount of caffeine, followed by green tea."
etcetera.
Or they may say, "Black tea has the highest amount of caffeine."
Everyone is contradicting themselves.
The point is [that] there are no hard and fast rules.
You can have high [caffeine] content green tea, [and] you can have low caffeine content
green tea.
There are no hard and fast rules.
It's important that tea sellers give you accurate information.
If you want to make very broad generalizations then tea that's made from the tips and the
buds will have a tendency to have higher caffeine, and that relates to green teas and black teas,
and teas that are made from lower leaves will have a tendency to have lower caffeine, and
that moves you more into Oolong teas.
From independent studies that we have done, [by] sending our tea into labs, it has certainly
been true that Oolong teas tend to reside in that lower caffeine area.
[For] a quick word about decaffeinated teas, decaffeination of tea is an industrial process
using a solvent - either ethyl acetate, or supercritical CO2 - which is a solvent that
strips out the caffeine, but also strips out a lot of other good stuff, in terms of health
benefits and flavors, so I would stay well away from decaffeinated tea...
So how can you control how much caffeine actually ends up in the cup?
Well, the wonderful thing about loose leaf tea is that, unlike coffee - which is ground
up - you have a lot of control of the amount of caffeine that you extract in the brewing
process.
Of course, I am not talking about teabags here.
Teabags are commonly made with broken leaf and tea dust, which extracts very, very quickly
so you don't have the control.
In fact, it will produce a stronger, and more likely, very high caffeine tea.
If you are sticking to loose leaf then you have four brewing parameters that can control
the amount of caffeine that you're drinking.
The first is the amount of leaf.
The more leaf you use the higher the caffeine is going to be.
The second is the length of your steeping time.
The shorter your steeping time, the lower your caffeine is going to be.
The third is the amount of times that you drink; in other words, the amount of infusions
that you consume.
[Drinking] more infusions means you're going to be drinking more of the caffeine.
Lastly, temperature of water is paramount.
Boiling hot water will extract much more caffeine than cooler water.
which is probably why green tea is commonly thought of as a lower caffeine drink, because
it is traditionally brewed with lower temperature water.
Of course, I am not referring to Matcha here.
Because Matcha is a powder, and you're consuming the entire leaf, you are getting all of the
caffeine, and you have no control in the brewing process.
A shot of Matcha gives you about 17 milligrams of caffeine.
What about Western versus Gong Fu style brewing.
Well, with Western brewing you're brewing for longer periods of time - [like] two to
three minutes - compared with Gong Fu brewing, which is a matter or 20 to 30 seconds, but
you're using a lot more tea leaf with Gong Fu brewing.
So my guess - and it is only a guess - is that a cup of Gong Fu brewed tea, versus a
[large] cup of Western brewed tea, will have about the same amount of caffeine.
However, with Gong Fu brewing you are drinking many more infusions, so a session of Gong
Fu will definitely give you more caffeine.
That leads us onto our final myth to be busted, and that is that you can decaffeinate your
tea if you give the tea leaves a longer tea wash.
In other words, you put the loose leaf into hot water for 30 seconds, and then you pour
away that water.
This is not true.
Studies have shown that if you do this, a 30 second tea wash will extract - and therefore
you will throw away - something like 10 percent of the caffeine content.
So it will have an effect, but not very much.
If you really wanted to go over 90 percent of the caffeine extraction to throw away you
would have to be brewing for about 15 minutes, so you can imagine how much of the flavor
and health-giving properties of the tea you would be throwing away.
So, if you are caffeine sensitive, and you want to drink tea in the afternoon or late
evening, what do you do?
Well, the first thing is drink loose leaf.
[Secondly, use] spring-picked tea made from tea leaves that are lower down on the tea
plant.
These tend to be Oolong teas.
If you want to follow the studies on roasting then maybe pick a roasted Oolong.
You can also use Kukicha.
Kukicha is made from the stems of the plant, and not the leaves.
They will also have lower caffeine.
Then it is a matter of controlling and experimenting; reduce the amount of tea leaves that you use,
reduce the steeping time, reduce the temperature slightly, and do not brew too many infusions.
Don't go too far, [and] don't have too many infusions.
Remember, you can always keep the leaves for the next day, so when you wake up in the morning
you can use those leaves for your first cup of tea.
I did a video on how best to store your tea in between infusions.
I will put a link in the description below.
I hope that this video has given you all the information that you need to control your
intake of caffeine, therefore optimizing your sleep, performance, and your enjoyment of
the tea.
That's it teaheads.
If you made it to the end of this video then please give [it] the thumbs-up.
Check out our YouTube playlists and let us know if there are any videos that you would
like us to make.
If you're ever in London then come visit us in Camden to say "Hi!" and taste our wares.
If you have any questions or comments then please fire them over.
Other than that, I'm Don Mei, [on] the beautiful island of Koh Samet.
Thank you for being a part of the revelation of true tea.
Stay away from those tea bags, keep drinking the good stuff, and spread the word, because
nobody deserves bad tea.
Bye [WAVING]