9 Coffee Myths Completely Debunked (Expert Guide 2025)
When I started Coffee Voilà, I had a lot of wrong notions about coffee in general. I believed dark roast had more caffeine, that drinking coffee on an empty stomach was a bad idea, and that decaf meant completely caffeine-free.
However, building a blog related to this niche required me to do some research to understand it. And let me tell you: I was shocked at how many of these so-called “facts” were actually Coffee Myths instead!
So in this guide, you’ll discover 9 of the most common coffee myths with science-backed facts. By the end, you’ll know exactly what’s true, what’s not, and how to enjoy your coffee without unnecessary worry.
Quick Explanation: Myths vs Reality
| Myth | Reality |
|---|---|
| 1 – Dark Roast Has More Caffeine Than Light Roast | Light roast retains more caffeine than dark roast because roasting reduces caffeine levels. |
| 2 – Coffee Dehydrates You | Moderate coffee consumption does not dehydrate you; it contributes to daily fluid intake. |
| 3 – Drinking Coffee on an Empty Stomach Is Bad for You | Coffee may trigger acid production but does not cause ulcers or major health issues in most people. |
| 4 – Espresso Has More Caffeine Than Drip Coffee | Per ounce, espresso has more caffeine, but a regular cup of drip coffee has more total caffeine. |
| 5 – Coffee Causes Insomnia | Caffeine has a half-life of 5-6 hours, so consuming it early in the day won’t interfere with sleep for most people. |
| 6 – Coffee Stunts Your Growth | No scientific evidence supports this claim; it likely started due to concerns about calcium absorption. |
| 7 – Coffee Is Bad for Your Heart | Moderate coffee consumption may actually lower the risk of heart disease. |
| 8 – Decaf Coffee Has Zero Caffeine | Decaf still contains small amounts of caffeine, usually 2-5 mg per cup. |
| 9 – Adding Milk or Sugar Ruins Coffee’s Health Benefits | Milk provides calcium and protein, and a small amount of sugar doesn’t negate coffee’s antioxidants. |
Myth #1 – Dark Roast Has More Caffeine Than Light Roast
I used to think dark roast coffee packed the biggest caffeine punch. It just made sense—stronger taste, bolder aroma, and that deep, almost smoky bitterness had to mean more kick, right?
I even remember ordering the darkest roast on the menu during college finals, convinced it would keep me wired through an all-nighter. Well, I had it completely backward.
Here’s the deal:
Caffeine is actually highly stable during roasting, meaning the difference in caffeine between light and dark roast is minimal.
While prolonged roasting can cause a slight reduction in caffeine, it’s not significant enough to make a major impact on your energy levels.
The real difference comes down to density.
- Light roast beans don’t spend as much time in the heat. So they remain denser than dark roast beans, which expand and lose mass during roasting. This affects how caffeine is measured in a cup of coffee.
If you measure by weight, dark and light roasts have almost the same caffeine content since weight compensates for density differences.
But if you measure by volume (like scooping your coffee), light roast wins every time because denser beans pack more caffeine per scoop.
Myth #2 – Coffee Dehydrates You
Studies have shown that moderate coffee consumption doesn’t dehydrate you.
Reality
In fact, the fluid in coffee contributes to your daily hydration needs.
The caffeine does have a mild diuretic effect. In other words, it might increase urine production slightly. But not enough to offset the water you’re drinking.
So, unless you’re downing five or more cups in one sitting, dehydration isn’t a concern.
Myth #3 – Drinking Coffee on an Empty Stomach Is Bad for You
Many claim coffee irritates the stomach if consumed without food.
Reality: Coffee Doesn’t Necessarily Harm Your Stomach
The research suggests that while coffee can increase stomach acid production, it doesn’t cause ulcers or harm most people’s digestive systems.
If you’re prone to acid reflux, you might feel some discomfort drinking coffee on an empty stomach. However, for most of us, it’s perfectly fine. There’s no solid evidence that coffee alone leads to chronic stomach issues.
That being said, I did notice that on days when I had coffee before eating anything, I sometimes felt a little jittery or even slightly nauseous.
If that happens to you, here’s a quick fix:
Try switching to a lower-acid coffee, adding a splash of milk, or drinking water before your first sip. Also, cold brew tends to be less acidic than hot coffee, so that might help if you’re sensitive.
Myth #4 – Espresso Has More Caffeine Than Drip Coffee
Espresso is often seen as the most caffeinated coffee option.
Reality: Espresso Is Stronger Per Ounce, But Drip Coffee Wins Overall
I used to think that if I really needed a caffeine boost, an espresso shot was the way to go. It just felt more intense. The small cup, the rich, bold flavor, and that quick, concentrated hit.
I remember downing a double shot before a long drive, convinced I was getting double the energy. Well, I was only half right.
Yes, espresso has more caffeine per ounce about 63 mg of caffeine per 1-ounce shot compared to 12-16 mg per ounce in drip coffee.
But here’s the thing:
Most people drink a full cup of drip coffee, usually 8-12 ounces, which adds up to 95-200 mg of caffeine per cup. So, while espresso feels stronger because you drink it quickly, a regular cup of drip coffee actually delivers more total caffeine.
Myth #5 – Coffee Causes Insomnia
Some avoid coffee thinking it will ruin their sleep.
Reality: Timing Your Coffee Matters More Than Avoiding It
Caffeine has a half-life of about 5-6 hours, which means if you drink a cup at noon, half of that caffeine is still in your system by dinnertime.
But here’s the catch:
Everyone metabolizes caffeine differently. Some people can down an espresso after dinner and sleep like a baby, while others (me, on a bad day) feel wired from a single afternoon latte. It’s not the coffee itself that causes insomnia. But it’s when and how much you drink.
For most people, if you stop drinking coffee by early afternoon, it won’t mess with your sleep. If you’re sensitive to caffeine, try switching to decaf or half-caf in the afternoon. I also found that staying hydrated helps. Because it isn’t the caffeine that keeps you up, but dehydration or over-stimulation.
Note: So, if coffee keeps you awake at night, don’t panic. Just adjust your timing and experiment with what works for you. Your morning cup (or two) isn’t the enemy. It’s just about knowing your limits.
Myth #6 – Coffee Stunts Your Growth
A widely believed myth that discourages kids from drinking coffee.
Reality: Coffee Has No Effect on Your Height
The whole idea is nothing more than an old wives’ tale. There’s no scientific evidence that coffee stunts growth. This myth likely started from concerns about calcium absorption, with people assuming that caffeine weakens bones.
While it’s true that excessive caffeine can slightly reduce calcium absorption. The effect is so small that it’s practically meaningless. Especially if you’re getting enough calcium from other foods like dairy, leafy greens, or fortified drinks.
Also, studies have shown that coffee has no negative impact on bone density or overall height.
The fact is your height is determined mostly by genetics, nutrition, and overall health, not by what’s in your mug. If anything, drinking coffee responsibly might help you feel more awake and productive. This is way more useful than an extra inch or two anyway!
Myth #7 – Coffee Is Bad for Your Heart
Many assume coffee raises blood pressure and harms the heart.
Reality: Coffee May Actually Be Good for Your Heart
Research has shown that drinking 1 to 4 cups of coffee per day helps lower the risk of heart disease, stroke, and even heart failure.
While caffeine can cause a temporary increase in blood pressure, especially in people who aren’t regular coffee drinkers. Usually, this effect is mild and doesn’t lead to long-term hypertension.
In fact, coffee contains antioxidants and anti-inflammatory compounds that may actually support cardiovascular health.
Now, that doesn’t mean you should start chugging six espressos a day. Like anything, balance is key.
If you’re sensitive to caffeine or have a heart condition, it’s always smart to check with your doctor. But for most people, a couple of cups of coffee a day can be part of a heart-healthy lifestyle.
Myth #8 – Decaf Coffee Has Zero Caffeine
People think decaf is 100% caffeine-free.
Reality: Decaf Still Contains Small Amounts of Caffeine
I used to think that decaf coffee was completely caffeine-free. Like, zero caffeine, totally safe for a late-night cup without risking a restless night.
Imagine my surprise when I found out that decaf still contains small amounts of caffeine. I mean not much, but enough that it could make a difference for people who are sensitive to it.
Most decaf coffee still has about 2-5 mg of caffeine per 8-ounce cup, compared to the 80-100 mg in regular coffee. That might not sound like much.
However, if you’re drinking multiple cups of decaf throughout the day, it can add up. The caffeine content can also vary depending on the decaffeination process—some methods remove more caffeine than others.
If you’re trying to cut out caffeine completely, you might opt for herbal tea or other caffeine-free alternatives.
Myth #9 – Adding Milk or Sugar Ruins Coffee’s Health Benefits
Some say black coffee is the only “healthy” way to drink it.
Reality: Milk and Sugar Won’t Destroy Your Coffee’s Benefits
Actually, adding milk provides nutritional benefits. For instance, it’s a great source of calcium and protein, which can be good for bone health.
If you enjoy a splash of dairy or even a plant-based alternative like oat or almond milk, your coffee is still packed with antioxidants.
In fact, some studies suggest that milk proteins can help slow the absorption of caffeine, giving you a more steady energy boost rather than a quick spike and crash.
And sugar? A little bit won’t hurt. Yes, excessive sugar can give you health issues. However, a teaspoon or two in your coffee isn’t going to undo all the good things coffee offers.
If you’re worried about sugar but don’t like coffee plain, try natural sweeteners like honey, cinnamon, or even vanilla extract.
Last Thoughts
So, have you busted any coffee myths yourself, or do you have questions about your daily brew? I’d like to hear your comment below and with that voilà!
