What Caffeine Really Does to Your Body

A check-up on your morning cup of wake-up

Curious About Coffee?


You’ve reached for that morning cup of joe (or tea) for years. It’s part of your routine and frankly, you can’t dream of life without it. But what does caffeine really do to your body once you’ve taken a sip?

Let’s break down caffeine – what it is and what it does – and take a closer look at its health benefits and risks.

What is caffeine?

You won’t be surprised to learn that caffeine is a stimulant. It’s also a natural substance found in over 60 different plant species all over the world like coffee beans, tea leaves and kola nuts. There are also synthetic forms of caffeine used in various products like sports drinks, nutritional supplements, water and even personal care products. Seriously.

Natural and synthetic (or “added”) caffeine are nearly identical in their chemical makeup.

What does caffeine do once it enters your body?

Once you pop a pill or take a swig of your favorite revved-up beverage, caffeine goes straight to work on various systems in your body.

First, caffeine stimulates your sympathetic nervous system, the system in your body responsible for your "fight or flight" response. Caffeine signals your brain to amp-up production of adrenaline, which in turn increases your heart rate, blood pressure and blood flow to your muscles.

It takes about 360 milligrams of caffeine (roughly three-plus cups of drip coffee) to have a significant effect on your heart rate. The increase in heart rate makes you feel more alert after that first cup but might make you feel jittery on a multi-cup kind of day.

Caffeine intake also tells the body to send more blood to the stomach and signals the liver to release sugar into the bloodstream for extra energy.

What are the health benefits of caffeine?

After the FDA removed caffeine from its list of cancer-causing substances in 2016, the medical community has invested significant time in researching its potential health benefits. Studies show that there are more than just a few potential wellbeing benefits that come with caffeine intake.

•    Lower risk of Type 2 Diabetes
•    Decreased risk of Parkinson’s Disease
•    Potential decrease in risk of death by suicide

In addition to getting you going at the top of each day, studies have also shown that coffee is a good source of antioxidants and helps increase performance during exercise.

Are there any negative effects that caffeine can have on the body?

Anything you put in your body can be detrimental in excess. Caffeine is no different. Up to 400 milligrams of caffeine per day is a universally accepted “safe” level for the average person, though some people can suffer adverse effects from consuming less. It all has to do with how quickly your body metabolizes caffeine.

There are also some health conditions; however, that might fare better if those suffering from them steer clear of caffeine.

  • Bone density: Some studies have shown that increased caffeine intake can reduce bone density in women, leading to osteoporosis.
  • Anxiety: If you live with diagnosed anxiety, consuming caffeine can make those symptoms worse. Caffeine-induced Anxiety Disorder is one of four caffeine-related syndromes in the DSM-5.
  • High blood pressure: If you suffer from high blood pressure, caffeine raises your blood pressure even more and could harm your cardiovascular health. 
  • Digestive issues: Caffeine can lead to stomach irritations, including GERD (gastro-oesophageal reflux disorder, also known as heartburn).
  • Insomnia: Your sleep may suffer since the same brain receptors that usually take-up adenosine, a brain chemical that causes drowsiness, also take-up caffeine.


The bottom line with caffeine? It's important to remember that it's a stimulant, which is why you love it first thing in the morning and perhaps as a boost after your lunchtime lull. Once it goes into your body, however, it affects multiple systems and organs. As you journey through life and face health challenges, be sure to keep your caffeine intake habits top of mind and share them with your health professionals.

You never know when your favorite cup of wake-up could shine a light on what might ail you.

E. Napoletano is an award-winning journalist and the recipient of the 2019 Illinois Women’s Press Association first-place prize for her feature on the traumatic effects of family separation policies at the border.