Whether you start each day with a strong cup of coffee or only have a soda when you need to stay up late, we all know what caffeine's good for. But how much do you really know about what caffeine does to your body (and your brain?)
What Is Caffeine?
Caffeine is a chemical that stimulates your central nervous system as well as your muscles, heart, and other parts of your body that help control blood pressure. The bitter substance is found naturally in the leaves and seeds of over 60 plants. Caffeine can also be made in a lab and added to foods, medicines, and drinks.
Because it helps you feel more alert, caffeine could be thought of as a "mind-altering" drug. But in moderate amounts, the FDA has labeled it a food product that's generally recognized as safe (GRAS).
How much caffeine is too much?
If caffeine is part of your daily routine, you may wonder if there's a "Goldilocks" amount. There is.
If you're in good health, experts advise having no more than 400 milligrams each day. That’s the amount you’d find in four 8-ounce cups of coffee. (The "short" size at Starbucks is 8 ounces.)
Teens should have far less caffeine each day -- only one cup of coffee or two cans of soda.
Foods With Caffeine
You can find caffeine in:
No surprises here. This drink, which is made from roasted coffee beans and piping hot water, is one of the most popular natural sources of caffeine.
Made from steeping tea leaves in hot water, tea has less caffeine than coffee. But it contains natural plant compounds that slow down the release of caffeine, so you might feel the effects longer than you would after drinking coffee.
Kola nut is the seed of the cola plant. Used widely in West African countries as part of cultural traditions and to make some types of medicine, cola extract is also often used to flavor sodas and energy drinks.
This dessert favorite comes from the cocoa plant. The amount of caffeine in chocolate products varies, but darker chocolates usually have more caffeine than milk chocolates.
5. Snack bars and energy drinks
Guarana is a plant named after the Guarani tribe, who brewed a drink using its seeds. Indigenous people in South America have used guarana as a medicine for many years. Now, it's often in caffeinated products like snack bars and energy drinks. But because it's usually very processed, you're likely getting caffeine without any other health benefits.
How much caffeine is in coffee?
The amount you'll find in your morning (or afternoon) brew depends on the kind of coffee you have and how much you drink. As a rule of thumb:
- 1 cup (8 ounces) of coffee contains about 95 milligrams of caffeine.
- Decaf coffee has only 4 milligrams.
- A shot of espresso has 65 milligrams of caffeine.
How does that compare to other caffeinated foods and drinks?
- A 1-ounce square of dark chocolate has about 24 milligrams of caffeine. (Milk chocolate has only 6 milligrams.)
- A 12-ounce can of regular or diet dark-colored soda contains about 40 milligrams of caffeine.
- 1 cup of black tea contains about 47 milligrams of caffeine.
- A 16-ounce energy drink contains about 200 milligrams of caffeine.
Caffeine Myth No. 1: Caffeine Is Addictive
Caffeine doesn't threaten your health the way addictive drugs do. But if you stop all caffeine cold turkey, you may feel the effects for a day or more, especially if you usually have two or more cups of coffee a day.
Symptoms of caffeine withdrawal can include:
- Feeling tired
- Feeling anxious
- Getting easily upset
- Depressed mood
- Finding it hard to focus
Caffeine, unlike some drugs and alcohol, doesn't cause severe withdrawal symptoms. (And if you slowly cut back the amount you have over a few weeks, you may not have withdrawal symptoms at all.) Because of that, experts don't label regular caffeine use as an addiction.
Caffeine Myth No. 2: Caffeine Keeps You Up at Night
Your body quickly absorbs caffeine. It also gets rid of it quickly. Processed mainly through your liver, some caffeine does stick around in your body for several hours. But for most people, a cup (or two) of coffee in the morning won't make it hard to fall asleep at night.
It's a different story if you wait to have your cappuccino or energy drink until late in the day. As a general rule, try to have caffeine at least 6 hours before bedtime. You may need an earlier cut-off if you're very sensitive to caffeine. If not, you may not only have trouble sleeping, but other side effects as well, like feeling nervous and having an upset stomach.
Caffeine Myth No. 3: Caffeine Raises Your Risk for Osteoporosis, Heart Disease, and Cancer
Here are the facts:
Osteoporosis and caffeine. High levels (more than 744 milligrams/day) of caffeine may increase the calcium and magnesium you lose when you pee. These two minerals are key for bone health. The good news? You can offset the calcium you lose by adding just 2 tablespoons of milk to a cup of coffee. Research does show links between caffeine and hip fracture risk, so if you're an older adult, talk to your doctor about whether you should limit your daily caffeine.
Heart disease and caffeine. A slight, short-term rise in your heart rate and blood pressure is common if you're sensitive to caffeine. But several large studies haven't linked caffeine to higher cholesterol, irregular heartbeats, or an increased risk of heart disease. If you already have high blood pressure or heart problems, talk with your doctor about your caffeine intake. You may be more sensitive to its effects. Also, caffeine could increase your chances of a stroke, although more studies need to be done.
Cancer and caffeine. Reviews of 13 studies involving 20,000 people revealed no link between cancer and caffeine. In fact, caffeine may even protect you against certain cancers.
Caffeine Myth No. 4: Caffeine Is Harmful if You're Trying to Get Pregnant
Many studies have not been able to find links between small amounts of caffeine (200 milligrams of caffeine, or about two cups of coffee per day) and any of the following:
- Trouble getting pregnant
- Birth defects
- Premature birth
- Low birth weight
But you do want to make sure you watch your caffeine intake. Having 200 milligrams or more of caffeine per day has been shown to increase the risk of miscarriage or low birth weight.
Caffeine Myth No. 5: Caffeine Dehydrates You
Caffeine helps pull extra fluid from your body, which causes you to pee more than usual. But the fluid you get in caffeinated drinks tends to make up for the amount you lose. The bottom line? Drinking a reasonable amount of caffeinated drinks won't dehydrate you.
Caffeine Myth No. 6: Caffeine Isn't Healthy for Kids
As many as 75% of kids have some caffeine every day. One study found that kids between the ages of 8 and 12 have as much caffeine as you'd find in three cans of soda. The FDA hasn't set guidelines for how much caffeine is safe for children, but experts agree that the less they have, the better.
If your child is sensitive to caffeine, having it could make them anxious or cranky, followed by a "crash" in energy. Also, most caffeine that kids drink is in sodas, energy drinks, or sweetened teas, all of which are high in sugar. That can put kids at higher risk for long-term health issues like diabetes and heart disease.
Caffeine Myth No. 7: Caffeine Can Help You Sober Up
Research suggests that caffeine only makes you think that you're sobering up. That's not the case. The truth is, your reaction time and judgment are still impaired, even if you feel more awake. College kids who drink both alcohol and caffeine are actually more likely to have car accidents.
Caffeine Myth No. 8: Caffeine Has No Health Benefits
We know that caffeine can:
Boost energy levels
By far, the most famous effect of caffeine is its ability to help you get going or recharge. That's because it's a stimulant, which helps lift your mood, improve your focus, and mask how tired you feel.
Your body needs energy for everything you do, even just sitting at your desk and looking at a computer. The process of turning food and drink into fuel is called metabolism, and caffeine may give it a boost. The amount of caffeine found in a single cup of coffee has been linked to a 3%-4% increase in metabolic rate. This means that caffeine may slightly increase the number of calories you burn in a day.
Experts are still studying whether this effect happens on its own. Because caffeine makes you feel less tired, it could also help you be more active.
Studies suggest that drinking a moderate amount of caffeine before you hit the gym can help improve your workout and reduce how tired you feel during it.
Caffeine may even make a physical activity feel easier, which can help you enjoy it more and do it more often.
May improve heart health
Since coffee is linked to an increased heart rate, you might think that caffeine ups your risk of heart problems. But in moderate amounts, caffeine may actually lower your risk of heart disease.
One study compared a wide variety of coffee drinkers and found that women who drank moderate amounts had a much lower risk of heart disease than women who drank even less.
Some evidence suggests caffeine may also reduce your risk of:
- Parkinson's disease
- Liver disease
- Colorectal cancer
- Type 2 diabetes
Caffeine may also help certain types of headache pain and asthma, but more research needs to be done.
Despite its benefits, don't forget that high levels of caffeine could end up harming your health. If you're not sure how much is right for you, talk to your doctor.