Now the dissertation dash may be over but there are unfortunates among us who still have to deal with exams. As a result you’ve traded writing your essays for the constant and repetitive task of revision, spending so much time in the library you actually have an assigned seat and overdosing on coffee. So how does coffee get you through these hard times? As you pop the next Pro-Plus and contemplate buying your fourth Red Bull of the day, here’s how it works.
The essential ingredient in all these products is caffeine. Discovered in 1819 by Friedrich Ferdinand Runge, it is essentially a Central Nervous System stimulant. Caffeine can promote alertness and wakefulness which makes it such a great ingredient to give us the top up of energy needed to read through those last lectures. Caffeine is metabolised by enzymes in the liver and creates alkaloids (compounds with basic nitrogen atoms) which can have different effects on the body. One of these – Paraxanthine – increases the breakdown of fat (which is why caffeine is often used in diet pills) thus elevating glycerol and fatty acids in blood which can give us more energy. Theobromine dilates blood vessels while Theophylline relaxes the smooth muscle of lungs and is used to treat asthma.
More to the point, caffeine can cross the blood brain barrier. This means it can directly act upon cells in the brain when ingested. Primarily, it acts as an antagonist of adenosine receptors. Adenosine is composed of an adenine molecule attached to a ribose sugar molecule. It plays an important role in energy transfer and is also believed to promote sleep. By and large, adenosine has an inhibitory effect on the nervous system. It acts to protect the brain by stopping neuronal activity and increasing blood flow. As an antagonist, caffeine counteracts this defence. Although we are not exactly sure yet how this mechanism creates attentiveness, it definitely hinders neuronal rest. Interestingly, caffeine can also act on adenosine receptors in other tissues than the brain, effectively blocking the production of energy in the body. It could be said that caffeine is keeping our mind awake whilst blocking energy production in our bodies. Is that really effective?
There are obviously counter indications to large amounts of caffeine ingestion. Overuse can create an addiction as well as conditions such as nervousness, insomnia, headaches and heart palpitations. In extreme cases, a caffeine overdose can lead to extremely severe biological conditions and sleep disorders. But it has been shown to decrease the risk of developing Parkinson’s disease in men.
Overall, a moderate consumption (around 300 mg per day) of your favourite caffeine fix won’t hurt but beware of overdoing it! Necessary amounts to induce a reaction vary according to size and height but usually, caffeine takes less than one hour to start working and should last in your body up to four hours.
Cup of drip coffee = 115-175 mg
Espresso = 60 mg
Instant coffee = 65-100 mg
Can of Red Bull = 80 mg
Can of Coca-Cola = 34 mg
ProPlus tablet = 50 mg