Coffee and what it does to your body - BBC World Service

By the time you finish watching this video, eight million cups of

coffee

will have been drunk around the

world

. Coffee has been consumed for at least 1,500 years and some say its impact is so great that it helped fuel the Enlightenment, which gave rise to some of the great ideas that underpin the

world

as we know it. The main active ingredient in

coffee

is caffeine, considered the most consumed psychoactive drug on the planet.  So where

does

coffee come from and

what

does

it do to us when we drink it? Coffee comes from the fruit of the Coffea arabica plant native to Ethiopia.

One story goes that a 9th century goat herder named Kaldi saw that his goats were more energetic after eating coffee berries, so he took a bite too. Historical records suggest that the Sufis of Yemen roasted the seed of the coffee berry to create the drink we know today.  In the 15th century, the first coffee houses began to appear throughout the Ottoman Empire before spreading to Europe in the following centuries. The cafes of Europe became spaces to debate business, politics and new ideas.  One academic, Jurgen Habermas, even says that without coffee we would not have had the Enlightenment.  Philosophers such as Kant and Voltaire, who was said to drink up to 72 cups a day, began to question the Catholic Church's interpretation of the world.  Instead, they turned to science, believing that everything in the Universe could be explained rationally.

This so-called Age of Enlightenment radically changed the world as we knew it. It led to the overthrow of monarchs, the growth of democracy, and numerous scientific discoveries.  Coffee also fueled the slave trade. The French used African slaves on Haitian plantations, and in the early 19th century, Brazil produced a third of the world's coffee using African slaves. Did coffee also give rise to capitalism?  Companies began giving coffee to their workers and eventually allowed them to take coffee breaks. This was not an altruistic move.  They were trying to increase worker productivity.  Fast forward to the present, two billion cups of coffee are consumed every day.  It's a $90 billion a year industry.

And, more than that, it is a fundamental social part of the daily lives of billions of people. So how does coffee affect the

body

? When caffeine enters the digestive system, it is absorbed through the intestine into the bloodstream. But the effects only begin when the caffeine reaches the nervous system. This happens because caffeine has a chemical structure very similar to that of a substance produced by our own

body

: adenosine. Caffeine binds to the body's adenosine receptors, which can be found on the surface of nerve cells.  It's like a key that opens a lock. Adenosine is known to slow down the sympathetic nervous system: it reduces the heart rate and generates a state of drowsiness and relaxation.

By blocking these receptors, caffeine generates the opposite effect. Your blood pressure, for example, may increase slightly, especially if you are not used to drinking coffee frequently.  The same goes for brain activity: caffeine stimulates the brain, suppresses hunger and helps you stay alert, so you can concentrate for longer. Caffeine can have a positive impact on mood, inhibit feelings of fatigue, and improve physical performance.  For this reason, many athletes use it as a supplement.  These effects can last between 15 minutes and two hours.  The body eliminates caffeine within five to ten hours after consuming it, but the residual effects of caffeine can last even longer.

If you want to optimize the effects of caffeine on

your

body, experts suggest refraining from consuming it in the afternoon, so that

your

cup of coffee the next morning will have a greater impact.  Coffee also requires care when drinking it.  For healthy adults, the recommended limit is 400 milligrams of caffeine per day. It's about four or five cups of coffee.  Exceeding this limit can cause side effects such as insomnia, nervousness, anxiety, tachycardia, upset stomach, nausea and headache.  Toxic effects, such as seizures, can be seen after rapidly consuming about 1,200 milligrams of caffeine, which is equivalent to about 12 cups of coffee.

Of course, these limits vary from person to person: some people are genetically more sensitive to caffeine. But when drunk in moderation, coffee can be good for your health. For example, it is associated with a reduced risk of type 2 diabetes, cardiovascular disease, some types of cancer, and Parkinson's.  And these health benefits are not just related to caffeine. Coffee has other beneficial substances, such as chlorogenic acid, a powerful antioxidant that can reduce the risk of many diseases.  So the next time you have a cup of coffee, you may never look at it the same again.