6th December 2019

It’s time to spill the tea on coffee

Many students enjoy, and rely, on coffee but what are the effects on the body?
It’s time to spill the tea on coffee
photo: Nathan Dumlao @Unsplash

Did you know that coffee is the second most traded commodity on Earth after oil? Yes, this is right. The estimated global consumption of caffeine per day is 300 tones, making it the second most popular beverage in the world after tea.

We’ve spilled the tea on Britain’s tea addiction, but what about our reliance coffee?

Considering its well-known psychoactive effects on the brain, it is no surprise that coffee is also the most consumed drink among students, particularly during exam periods. With January exams around the corner, this article is dedicated to this caffeinated beverage that so many rely on.

Adenosine is an endogenous substance, one that originates in our bodies, which slows down the brain activity by binding to the adenosine receptors found on neurons. This molecule is responsible for the tiredness we feel due to lack of sleep or energy.

Caffeine, on the other hand, is a substance that is structurally similar to adenosine but with opposite effects on the brain, it induces complete alertness and improves our focus. Upon entering the body, caffeine molecules rapidly rush to the brain, compete with adenosine molecules and bind to these receptors resulting in decreased levels of adenosine. This biological process explains the rise of energy after drinking a cup of black coffee.

Additionally, caffeine is known to increase the levels of dopamine, also known as the ‘reward’ hormone. As a result, drinking a cup of coffee is enough to increase heart rate and blood pressure, as well as boosting your mood. However, these energising actions of coffee come with a cost. The more you drink, the more adenosine receptors your brain cells produce, so over time your body will need more coffee to get the same effect of alertness and response. The addictive effect of caffeine is actually more scientifically accurate to call a caffeine dependence.

But how much coffee is enough to produce these addictive effects and is it possible to overdose on caffeine?

First of all, it is hard to determine the exact dose of caffeine that will produce physical dependence in individuals as everyone has a different genetic predisposition to it. However, a bit of maths can help us decide how much coffee we need and want.

We know that one shot of espresso contains 212 mg of caffeine and that the half-life of caffeine is 5-6 hours. This means that the effects caused by a shot of espresso take between 10 to 12 hours to diminish completely. However, due to the significant decrease in effects after 5-6 hours of drinking coffee, many of us would enjoy a second cup of during the day. So, it could be suggested that 2 to 3 cups of coffee gives us the optimal amount of caffeine to keep us wide awake throughout the day, although it shouldn’t be necessary to rely on this to do so. Anything more than this amount is likely to cause a physical dependence along with temporary insomnia and dehydration. To our relief, it is practically impossible to overdose on coffee as the lethal dose of caffeine is 150 mg/kg, which means that a 70 kg adult would need to consume 10,500 mg of caffeine at once to overdose. That’s 25 Americanos or 50 Lattes!

Experts say that drinking coffee first thing in the morning may not be the best time. This is due to the fact that caffeine interferes with the stress hormones in the blood which is naturally high in the mornings. The combination of cortisol and caffeine may cause more tiredness throughout the day, so instead dietitians have suggested that the best time to drink a coffee is 2 to 3 hours after waking up. Additionally, studies have shown that having a cup of coffee before sleeping for a short period of time significantly enhances the effect of the caffeine and is sometimes referred to as a ‘coffee nap’.

The key to healthy coffee and caffeine consumption is know understand and know how your body responds to it, especially during intense periods of stress, such as exams, when you might be inclined to rely on the drink too much.

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