Today we're gonna talk about caffeine.
It's the most widely consumed psychoactive drug
in the world, most commonly consumed as coffee.
And we're all familiar with the effects of caffeine
but what exactly is caffeine?
Why do plants produce it?
What does it do to our bodies
and is it good for you?
Now, from a chemical perspective,
caffeine can be described as both a methylxanthine
and an alkaloid.
The first name refers to the shape
and composition of the caffeine molecule
while alkaloids as a whole are a broader group
of naturally occurring organic compounds,
defined by having at least one nitrogen atom.
Alkaloids have many functions and effects
but almost all are bitter in taste.
Caffeine occurs naturally in more than 60 different plants
but more surprising then that
is that those plants each develop
different biochemical mechanisms
and pathways to create caffeine.
This is a phenomenon known as convergent evolution.
Most people associate caffeine with coffee
and it is named for coffee
but it also occurs in tea,
chocolate, kola nuts, guarana seeds
and even the flowers of citrus plants.
Plants produce caffeine primarily as a pesticide.
It deters insects from attacking or eating the plant,
in part with its bitter taste,
but caffeine is also toxic to some herbivore insects.
It does also have one super interesting function.
Studies have shown that caffeine
can improve the memory of bees,
helping them create a stronger association
between the smell of a coffee flower
and its sweet nectar.
This might be why caffeine exists
in very low concentrations in the nectar
of certain flowers, like the citrus flowers
we mentioned before.
It gives those plants a competitive advantage
in the world of pollination.
Human consumption of caffeine likely starts back
in 3,000 B.C. with the consumption of tea.
And tea, gram for gram,
has more caffeine than coffee
but we just use more coffee when we make a cup.
The beginning of coffee consumption
is a little bit harder to pinpoint
but by the middle of the 15th century,
we're pretty confident that coffee drinking
had taken hold in Yemen and the surrounding areas.
With both tea and coffee,
very early records shows that people liked it
for the stimulating properties of caffeine.
Credit for the discovery of caffeine
is not quite clear cut.
In 1819, a German chemist named Friedlieb Ferdinand Runge
isolated what he called kaffebase,
a nearly pure caffeine extract.
He did this work apparently
at the suggestion of the famous writer,
Johann Wolfgang von Goethe.
Runge is also notable
for having been the first to isolate quinine
and also for the invention of paper chromatography.
In 1821, it was discovered independently
by French chemist Pierre Jean Robiquet
to whom caffeine's discovery had traditionally,
historically been credited.
It was also discovered at the same time
by two other French chemists working together,
Pierre-Joseph Pelletier
and Joseph Bienaime Caventou.
Pelletier was the first to use the word caffeine
in print, though Robiquet was the first
to isolate and describe the properties
of pure caffeine.
In that pure form,
caffeine is a white, crystalline powder
that has a pretty bitter taste.
If you take a large enough dose, it's toxic
but in lower doses,
if you look at how it affects humans,
you start to understand its enduring popularity.
Now, most people consume caffeine
by drinking coffee and it's absorbed initially
through the gastrointestinal tract
and then 30 to 60 minutes after consumption,
that's when it reaches peak concentrations in the body.
Let's get into some biology here.
Now, caffeine affects the body
with three different mechanisms.
Firstly, caffeine blocks the receptors in the body
for a compound called adenosine.
Under normal circumstances,
adenosine triggers these receptors
and it produces a feeling of relaxation
and even drowsiness for some people.
And so caffeine prevents this from happening,
while also causing the body to increase production
of dopamine and noradrenaline.
This is the mechanism behind most
of the effects that we all experience with caffeine,
this inhibition of adenosine.
It happens at relatively low doses
and gives us that feeling of wakefulness
or alertness that we associate with a cup of coffee.
This mechanisms might also explain the kind
of caffeine crash that many people experience
with a sudden feeling of tiredness and exhaustion.
It might be that once the body metabolizes all
of the caffeine, then the adenosine
is finally able to trigger those receptors
and really, really make us feel tired and drowsy.
Caffeine also causes the release of calcium
inside of muscle cells
and it can prevent or slow its reuptake.
This increased availability of calcium
increases the power output of the muscles
but it does require a pretty large dose to occur,
around 500 milligrams for an average person.
Caffeine can inhibit what are called phosphodiesterase,
now, if you stop these enzymes working properly,
then you can actually cause the body
to burn more fat.
But for this to work,
it also requires a much larger dose
than people would typically get
from drinking a few cups of coffee in a day.
Caffeine affects the central nervous system.
Caffeine makes us feel more alert, more awake
and has been shown to improve memory.
However, the beneficial effects of caffeine
aren't as clear cut as we would like.
Several studies have now shown
that that improved mental clarity that we get
when we drink coffee in the morning,
well, that comes from alleviating our withdrawal symptoms,
rather than actually improving our cognitive functions.
One positive impact is the increasing evidence
for caffeine's ability to act as both a treatment
for some aspects of Alzheimer's and Parkinson's,
as well as having some preventative properties as well.
Now, caffeine could be said
to be the last legal performance-enhancing drug
but it wasn't always this way.
Between 1984 and 2004, caffeine was actually
on the Olympic Committee's banned list.
If they tested your urine
and you were at a higher concentration
than 12 micrograms per milliliter, you were out.
And to hit that level,
you could do it with just five to eight cups
of coffee in the morning.
And because people metabolize caffeine differently,
this was ultimately an unfair thing to police
and after 2004, it was off the banned list.
Now, as we talked about before,
caffeine does affect the muscles,
it does affect power output
but it does seem less effective
with habitual users of caffeine.
Though it does impact the perception
of exertion and fatigue,
which is kind of interesting.
For people using caffeine for sport,
they're typically dosing three to five milligrams
per kilo of body weight.
Now, not everyone has a positive experience with caffeine
and we do need to talk about that.
Symptoms like mild anxiety, jitteriness,
insomnia, reduced coordination,
these are all symptoms people can suffer
with even mild caffeine consumption.
Caffeine can have a negative effect on anxiety disorders
and doses above 300 milligrams
can worsen someone's anxiety.
However, lower, more moderate doses
have been shown to be associated
with reduced symptoms of depression.
Consuming coffee regulatory does leave you susceptible
to experiencing caffeine withdrawal if you stop suddenly.
Now, most people can experience a big headache
that can last a little while.
They can become irritable, fatigued,
some can get flu-like symptoms or struggle to concentrate.
Typically these symptoms will last
for up to 24 hours, though occasionally,
it can go on for longer
and people have experienced caffeine withdrawal
for up to three days.
So how much caffeine exactly is considered healthy?
Recommendations are quite broad
because people respond to
and metabolize caffeine a little bit differently
but current guidelines are for an adult,
it's no more than 400 milligrams of caffeine per day.
And that's 200 milligrams
if you're pregnant or breastfeeding.
Soft drinks, energy drinks, tea
are all popular sources of caffeine
but coffee is by far the most popular.
But with soft drinks and energy drinks,
there is typically a fixed
and known amount of caffeine in them.
You can look up on the internet how much coffee
is in a can of Coca-Cola.
With coffee, you can't.
A cup of coffee will have quite a dramatic variance
in its caffeine content,
depending on a number of factors.
The coffee itself will play a role.
Arabica has half the caffeine content of Robusta
but the recipe or the way that it was brewed,
these will all have an impact.
And they've gone and done tests
and bought coffees from different cafes
and there's been a pretty wide range reported,
anywhere from around 65 up to over 300 milligrams
in a single cup.
Various governments and governing bodies
have tried a few times
to legislate coffee companies
to have them tell you exactly how much caffeine
is in your coffee-related product
but so far, that's never happened.
It's always been successfully lobbied against.
Excessive caffeine consumption
can be quite unpleasant
and actually, it can be fatal.
To reach caffeine toxicity,
you'd have to ingest around 10 grams of pure caffeine
in a day.
To do that, you'd have to drink between 50
and 100 cups of coffee.
So it's actually pretty rare
that anyone reaches that from drinking coffee.
More often, people have died from caffeine intoxication
from consuming too many caffeine pills
or other medications that may contain caffeine.
I think for those of us who drink
and enjoy coffee all the time,
it's really important
to understand a bit more about caffeine.
This is a psychoactive drug
that we're taking every single day.
We should understand what it is
and how it affects us.
Now, I know you'll probably have questions
about decaf and decaffeination
and I promise, I'll answer them all in a future video.
And if you wanna know more about caffeine,
I've left you some reading down
in the description below.
But for now, I'll say thank you so much for watching
and hope you have a great day.