Stay curious!

“First, I need coffee!” Sounds familiar? You’re not alone. That groggy, sluggish feeling in the morning often disappears after a few sips of coffee. Suddenly, you’re not just awake—you’re dancing through the kitchen, full of energy.

But how healthy is this beloved brew, really? Coffee used to have a bit of a bad rep. These days, research tells a more nuanced—and surprisingly positive—story. In this post, we’ll break down what’s actually in coffee, how caffeine wakes you up, whether coffee increases cancer risk, how much you can safely drink, and why some people can handle it better than others. Ready? Let’s dig in.

What is caffeine?

Coffee contains over 1,000 substances, but caffeine is the best known—and the most powerful.

Chemically, caffeine is part of a group called alkaloids and is medically classified as a drug. Sounds intense, but don’t worry—it’s a legal one. It works by stimulating your central nervous system, boosting focus, alertness, and even physical performance.

Caffeine is naturally found not just in coffee beans but also in cocoa beans, tea leaves, guarana berries, and kola nuts. It’s even added to some medicines, cosmetic products, and snacks (yes, even ice cream).

How does caffeine work in the body?

It takes around 15 to 30 minutes after drinking coffee for caffeine to kick in. Once consumed, it travels from your stomach and small intestine into your bloodstream—and eventually, into your brain.

Here’s the fascinating bit: when we use energy throughout the day, a compound called adenosine builds up in the brain, binding to receptors that signal it’s time to rest. Caffeine mimics adenosine, binding to the same receptors and blocking the sleepy signals. So instead of “you’re tired,” your brain gets “you’re fine—keep going!” 

Caffeine also increases adrenaline and cortisol, two hormones that rev up your heart rate and blood pressure, helping you feel even more awake. This buzz usually lasts one to two hours.

What happens during caffeine withdrawal?

Ever skipped your morning cup and felt like a zombie? That’s withdrawal. About 12–24 hours after your last caffeine hit, your body starts to protest—cue headaches, fatigue, and poor concentration. This is because your brain now has more adenosine receptors than usual, making you feel extra tired without caffeine to block them.

The good news? Most people recover in a day or two. And interestingly, drinking coffee less often makes the stimulating effect stronger again. So taking a break now and then might make your coffee work better when you come back to it.

What else is in coffee?

Besides caffeine, coffee comes with a surprising range of goodies:

• B vitamins
• Minerals like potassium, calcium, magnesium, and phosphorus
• Antioxidants

Scientists are still exploring the full list of coffee’s active compounds—there are a lot—but some of them may help explain its link to better health outcomes.

Does coffee increase the risk of cancer?

This used to be a real concern. Until 2016, the World Health Organization classified coffee as possibly carcinogenic—mainly because of older studies that failed to separate coffee consumption from smoking habits. But after reviewing over 1,000 studies, experts concluded there’s no strong evidence linking coffee to cancer. In fact, some studies suggest the opposite: coffee might offer some protection against liver, prostate, kidney, colon, and even skin cancers. The Cancer Information Service in Germany highlights this emerging (but still cautious) optimism.

What about hot coffee?

Here’s a twist: it’s not coffee itself that raises red flags—but its temperature. Drinking beverages hotter than 65°C may increase the risk of esophageal cancer, likely because extremely hot liquids can damage cells in the throat. So let your drink cool down just a bit—it’s not just better for your tongue, but possibly your health too.

Do coffee drinkers live longer?

A massive European study involving over half a million people across 10 countries found that coffee drinkers had lower mortality rates. Pretty encouraging, right? That said, correlation isn’t causation. It might not be coffee itself but the overall lifestyle of coffee drinkers that makes the difference. Still—if you’re enjoying your morning cup, this is one more reason not to feel guilty about it.

How much coffee is actually safe?

Let’s talk numbers. According to the European Food Safety Authority (EFSA), a healthy adult can safely consume up to 400 mg of caffeine per day—that’s around 4 to 5 cups of coffee. A single dose shouldn’t exceed 3 mg per kg of body weight. So if you weigh 60 kg, that’s a safe 180 mg in one go. For reference, a typical cup of coffee has between 30 and 100 mg of caffeine, depending on the type and strength.

And according to cardiologists, 3–5 cups daily might even reduce the risk of cardiovascular disease, stroke, or heart attack. 

Can coffee interact with medications?

Yes, and it’s important to know when. Caffeine can interfere with how medications are absorbed or how they work—either enhancing or weakening their effects.

For example:

• Painkillers like ibuprofen or paracetamol may work better with caffeine.
• Sedatives or calming meds might be less effective.

Fun fact: the migraine medication I use contains caffeine, precisely to boost its effect.

Can you drink coffee at the wrong time?

Timing matters.

• With meals: Coffee can interfere with iron absorption. If you’re low in iron, try spacing out your cup from iron-rich meals.
• In the evening: Caffeine can disrupt your sleep—though how sensitive you are depends on your genes and metabolism.

Some people can sip an espresso at 9 p.m. and sleep like a baby. Others stay awake for hours after a 3 p.m. latte. Know your body and adjust accordingly.

So, is coffee healthy?

In moderation—yes! Coffee can give you energy, support concentration, and might even offer long-term health benefits. But like most good things, the key is balance. Don’t overdo it, listen to your body, and give your adenosine receptors a break now and then. And next time you reach for your morning brew, do it with a little more appreciation for all the fascinating chemistry in your cup.

References

Burke, T. M. et al. (2015). Effects of caffeine on the human circadian clock in vivo and in vitro. Science Translational Medicine. Link

Cochrane Library. (Updated 2021). Caffeine as an adjuvant to pain medication for acute pain in adults. Link

EFSA (2015). Risk assessment of caffeine. PDF

Ehlers, A. (2016). Koffeinhaltige Lebensmittel aus Sicht der Risikobewertung. BfR.

Gunter, M. J. et al. (2017). Coffee Drinking and Mortality in 10 European Countries: A Multinational Cohort Study. Annals of Internal Medicine.

International Agency for Research on Cancer (IARC), WHO.

Islami, F. et al. (2019). Tea drinking temperature and risk of esophageal squamous cell carcinoma. International Journal of Cancer.

Loomis, D. et al. (2016). Carcinogenicity of drinking coffee, mate, and very hot beverages. The Lancet Oncology. Link

Nescafé. (n.d.). Coffee statistics UK. Link

Ong, J.-S. et al. (2018). Role of bitter taste perception in coffee, tea and alcohol consumption. Nature.

Rogers, P. J. et al. (2010). Caffeine effects and ADORA polymorphisms. Nature.

Sigmon, S. C. et al. (2009). Caffeine withdrawal and tolerance effects on brain and mood. Psychopharmacology.

van Dam, R. M. et al. (2020). Coffee, Caffeine, and Health. The New England Journal of Medicine. Link