Coffee and health: How does coffee affect our bodies?

There is a lot of information and misinformation out there about the effects of coffee on our health. It’s strange that one of the World’s most popular beverages should be such a mystery to so many people. This article seeks to demystify coffee by giving you scientifically verified information—cutting through the nonsense and clickbait articles found all over the web. So read on if you want to learn more about the effects coffee has on our bodies.

How does coffee affect your brain?

There have been countless studies into the effects coffee has on your brain. We wrote recently in our Office Worker’s Guide to Coffee about how coffee has been associated with preventing and slowing down forms of dementia such as Alzheimer’s disease.

Separate to safeguarding against dementia, however, coffee is linked to improving our day-to-day memory. A quick Google search will provide you with numerous studies on the topic, but this study by researchers at Johns Hopkins University illustrates most clearly that coffee improves memory. The study found that caffeine improves memory retention, especially when it comes to specific details of a memory. The study found that there was an optimal dose of caffeine in which to improve memory. This optimal dose is around 200mg of caffeine, which is roughly what you’d get in one strong cup of coffee. Below that dose and you don’t get the benefit, and above it can result in mild headaches and nausea. Although the study has proven that coffee improves memory, it is still a mystery why this is the case, so further studies are being carried out.

Coffee also affects your brain by making you more alert, helping you to focus on whichever task you’re on. Caffeine does this by tricking your brain. It tricks your brain by connecting to your nerve cells in the area where adenosine would usually connect (adenosine is one of the hormones responsible for making you feel sleepy). So caffeine effectively blocks out sleepiness. It also stimulates the production of adrenaline in your adrenal glands. This produces a smaller version of the fight or flight reaction we have when we’re in danger. This might sound a little dramatic, but it’s only a comparably small amount of adrenaline. The adrenaline creates several effects on your body, each of which we’ll go into below…


Your eyesight is improved by coffee as the adrenaline released by your adrenal glands causes your pupils to dilate, allowing more light into your eyes. With more light in your eyes, you are able to see sharper, richer images.


Your ability to breathe is improved by coffee as the adrenaline produced causes your breathing tubes in your lungs to dilate, allowing more air to pass through them, increasing the amount of O2 you produce and the amount of CO2 you expel. Put simply, caffeine makes your lungs more efficient and the extra oxygen makes you even more awake and more focused than you would be otherwise.


Your heart beats faster when you drink coffee as adrenaline is released into your bloodstream, stimulating your heart. This helps get oxygen around your body more quickly, making you more awake and alert. Your blood vessels on your skin also constrict; using less blood allows more blood for your muscles and brain. It’s one of the reasons why many weightlifters and bodybuilders have a cup of coffee half an hour before a big workout.


As with the blood vessels in your skin, blood flow to your stomach is slowed down, allowing more blood (energy + oxygen) to be used in your muscles and your brain.

Many people also claim that coffee can cause their stomach to hurt and there is some science backing this. The reason is that coffee is very acidic and many people tend to drink it in the morning, on an empty stomach. The result is that it not only makes your stomach acidic, it actually stimulates your stomach’s production of hydrochloric acid, despite there being no food to digest. Having a highly acidic stomach can cause stomach ulcers to develop as the bacteria H. pylori, known to cause stomach ulcers, thrives in acidic environments. It can also cause acid reflux as it relaxes the muscles at the entrance to your stomach, allowing the acid to move up your oesophagus. Coffee can also aggravate digestive problems such as IBS, colitis and Crohn’s Disease, so be wary of over consumption.

The best way to make sure over consumption of coffee doesn’t harm your stomach, and your digestive system in general, is to pay attention to how your body reacts. If you feel unwell, stop drinking it. The great thing is that your body recovers very quickly from any digestive irritation caused by coffee. Additionally, it’s always a good idea to have food with your mug of joe; doing this should significantly reduce your risk of developing stomach ulcers. Coffee isn’t dangerous; just as with any food or drink, it doesn’t agree with everyone and overconsumption or neglect can prove harmful.


The adrenaline released because of drinking coffee also causes your liver to release sugars into your bloodstream in order to give your body an extra boost of energy. Additionally, coffee has been proven to positively affect your liver. A large research project conducted by Kasier Permanente, in Oakland, California discovered that drinking 2–3 cups of coffee per day could reduce your chances of developing sclerosis of the liver by 40% and drinking four or more cups could prevent it by up to 80%. Importantly, this positive effect on the liver is not observed when we consume other caffeine-rich foods and beverages, so the benefit is unique to coffee!

Your muscles

The adrenaline produced when you ingest caffeine also causes your muscles to tighten up, readying themselves for action. This is perfect for exercise, so you may like to have a strong cup of coffee as your working day ends, just before you head to the gym.

Your bowels

Caffeine drinks can have a laxative effect. This is often a positive thing and many people praise coffee’s ability to keep them regular. Too much coffee in one morning, however, can cause diarrhoea. The best way to avoid this is to not overindulge, or to space out your coffee consumption throughout the working day. Also, if too much coffee has upset your tummy, then wean yourself off it slowly, over the course of a few days, so that your body doesn’t react to going cold turkey from the daily dose of caffeine.


Sometimes coffee is associated with headaches. But there is no evidence to suggest that caffeine causes headaches. However, if you are used to regular cups of coffee and you reduce this too quickly, then you may experience a mild throbbing headache. The reason for this is simple: caffeine causes the blood vessels in your head to dilate, so your body compensates for this a little on a regular basis. Then, when you reduce your caffeine consumption too quickly, the body is not used to this and overcompensates, causing the blood vessels in your brain to dilate too much—this can cause a headache. In extreme cases of caffeine withdrawal, someone can have a headache for over a week.

Coffee and teeth

Completely separate to its effect on your systems and organs, some people worry about coffee’s effect on their teeth. Coffee, just like other dark-coloured foods and drinks, can stain your teeth. It does this because the enamel on your teeth has tiny ridges and pits that hold on to food and stains. The same effect occurs with tea, read wine, cola, and other dark liquids. One piece of advice is to rinse your mouth out with water after you finish a cup of coffee; this way, the stains do not have time to permeate any deeper. If it’s possible to give your teeth a quick brush, then that’s even better! There’s one myth that adding milk or cream to your coffee will make it less likely to stain, and it’s understandable why people think this (as the while coffee in the mug looks much lighter than black coffee). However, white coffee still contains all of the staining chemicals you can find in black coffee, so adding milk or cream doesn’t actually make a difference to how much your teeth are stained by it.

Can caffeine make you tired?

Some people report that drinking coffee makes them tired, and there is a little bit of science to back this up. Luckily, there’s also a great way to prevent this form of tiredness. Here’s the science behind it: as caffeine is a diuretic, coffee drinkers find themselves nipping to the toilet a little more than usual and not replenishing their water levels. This means that a person can find themselves dehydrated a few hours after they consumed a couple of cups of coffee. This is also around the time that caffeine levels dip, so this alongside dehydration can make us feel sleepy. The obvious and easy solution to any sleepiness caused by drinking coffee is to keep yourself well hydrated throughout the day—and this is something you ought to be doing anyway.

That’s all we have time for today. We hope you’ve found this resource interesting and useful, and that you take one or two facts away with you about how coffee affects your body. At Amore Coffee, we’re coffee experts, and we have a wealth of knowledge about coffee we have gathered over the years selling and leasing coffee machines. Please get in touch if you have a question about coffee or our range coffee machines.