Caffeine: An Overview

We’re a nation of tea and coffee drinkers, in the UK it’s estimated we now drink around 95 million cups and coffee per day (1) and 84% of the British population drink tea and herbal infusions everyday (2). But how does this actually affect us? Particularly the caffeine content of these drinks.

What is caffeine?

Caffeine is a substance which stimulates our muscles, heart and central nervous system. It works by binding to adenosine receptors located in the central and peripheral nervous systems as well as in various organs, such as the heart, and blood vessels. Adenosine is a molecule involved in numerous biochemical pathways, mostly for energy transfer and signalling (3). Which leads to the desired effects including increased alertness and energy levels. Other effects include increased blood pressure and wakefulness. The reason many of us start the day with a warming cup of tea of coffee!

Where can we find it?

Classically known to be found in coffee, caffeine is also found in a range of foods and drinks including fizzy drinks, energy drinks, chocolate, black tea and green tea.

The concentration of caffeine in these foods and drinks naturally varies. And how individuals react to caffeine intake also differs. Factors including age, gender, weight, smoking, hormonal fluctuations, diet, genetics, medication and how regular consumption is all have an effect. For certain groups of the population including pregnant women and children, caffeine intake should be limited. For others including individuals that experience anxiety or IBS symptoms or that have disrupted sleep, reducing or limiting intake of caffeine may be beneficial.

Are there any benefits to caffeine consumption?

We sometimes see headlines about the positive effects of coffee, which is a change in direction from decades ago where coffee was labelled to interrupt sleep and making our hearts rate. Caffeine consumption can increase alertness and help to make us feel more awake, a pretty well-known benefit. The stimulant does this may enhancing brain function and increasing concentration.

There are also many alleged health benefits of caffeine including improving athletic performance and preventing type 2 diabetes. Research also suggests caffeine can lower the risk of liver and heart diseases and due to the potassium content of coffee, the drink is linked to lower blood pressure (4). Further benefits include preventing migraines or headaches which comes with very mixed evidence.

The stimulant can also help to stimulate bowel movements and contributes to overall daily fluid intake when consumed as coffee or tea.

What about possible disadvantages?

On the flip side, coffee can have undesired effects including decreasing iron absorption. This is due to tannins containing in the beverage. Avoid drinking coffee around mealtimes to avoid this and get the most from your source of iron! Caffeine can also cause gut irritation. It has been known to irritate the stomach due to the production of stomach acid and worsen symptoms of irritable bowel syndrome. It can also cause heartburn, acid reflux and indigestion in some individuals.

Not only that, but caffeine stays in our systems for much longer than we realise (up to 12 hours), so that 4pm cup of coffee could be disrupting your sleep or evening routine. Limiting caffeine intake in the afternoon or evening, after 12pm can be a good option.

Due to it’s effect on the nervous system caffeine can increase or cause anxiety and come with side effects such as increased heart rate or heart palpitations.

Caffeine can also lead to withdrawal symptoms. After all, caffeine is an addictive substance which your body becomes dependant on. This may include headaches or feeling very lethargic. This makes reducing intake difficult, as your body has become so dependant on the substance. But over time with perseverance your body will adapt.

How much should we have?

It is recommended that adults consume no more than 400 micrograms of caffeine per day (3,4) while 2.5 micrograms per kg per day for children and adolescents is advised. For pregnant women less than 200 micrograms is recommended (4).

The average cup of coffee contains around 90mg, depending on the type of coffee and how it’s made. A double espresso contains around 125mg and the more shots you have in your coffee, the more caffeine. But remember caffeine isn’t only found in tea and coffee!

Should we avoid it?

While the average individual does not need to avoid caffeine consumption completely, it’s important to be mindful of the recommended intakes, stated above, and remember caffeine is found in more than just your cuppa!

Intakes should be limited for certain population groups for example children and during pregnancy. This is because studies have linked caffeine intake (not coffee intake) with low birth weight babies. There are also certain medical conditions which necessitate caffeine intake to be limited/avoided including underlying heart conditions.

Ultimately we don’t need to go T-total on the caffeine, but we should be mindful of timing, quantities and types we are consuming on a daily basis. While there are benefits to consumption, if you don’t enjoy products containing caffeine there is no need to start consuming them to reap these benefits.



Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: