The Science-Backed Benefits and Side Effects of Caffeine

Most of us rely on caffeine to kickstart our day. You probably know about caffeine in coffee as a quick energy boost, but it’s also in tea, energy drinks and some medications. Better understanding caffeine’s effects on your mind and body can help you make informed choices about how much you should consume. Caffeine has a lot of benefits, but it has its downsides, too.

While caffeine may improve your focus and alertness, it can also have side effects like jitters, anxiety, or insomnia if you take too much.^[1] Knowing how much caffeine is in a cup of coffee (and yes, even in decaf coffee) can guide you in managing your intake. If you’re thinking about cutting back on coffee, you may run into caffeine withdrawal symptoms like headaches and fatigue, so it’s important to taper down rather than quit suddenly.^[2] Understanding the delicate balance between caffeine’s benefits and potential drawbacks allows more intelligent consumption that maximizes energy and minimizes unwanted effects.

What is Caffeine?

Chemically, caffeine is an alkaloid containing carbon, hydrogen, nitrogen and oxygen atoms.^[3] Its chemical structure allows caffeine to easily pass through your bloodstream and enter your brain, where it stimulates your central nervous system. That is why you feel more awake, alert and energized when you drink your first cup of coffee.

How Caffeine Works as a Stimulant

Caffeine blocks adenosine, a neurotransmitter in the brain that promotes relaxation and sleepiness.^[4] Under normal conditions, adenosine builds up in the brain throughout the day, making you tired. Consuming caffeine binds to the adenosine receptors without activating them, effectively blocking adenosine’s calming effects. As a result, you feel more alert and awake, even when you usually start to feel tired. Plus, caffeine increases the release of other neurotransmitters like dopamine and norepinephrine.^[5] These neurotransmitters can improve mood, focus, and concentration, enhancing mental and physical performance.^[6]

Sources of Caffeine

Caffeine can be natural or synthetic. Natural caffeine comes from plants, and you’ll find it in coffee, tea and hot chocolate, as well as in foods like dark chocolate. Synthetic caffeine is made in laboratories and added to products like energy drinks, sodas, pre-workout supplements, and over-the-counter medications. Synthetic caffeine is chemically identical to natural caffeine but is often absorbed more quickly in your body,^[7] which can lead to a more rapid energy boost. The downside is that it may increase the risk of jitteriness or an energy crash later.

The Science-Backed Benefits of Caffeine

Scientific studies help us better understand caffeine’s impact on the human body. So far, the research looks promising. Here are just some of the ways that caffeine may benefit you:?

Enhances Physical Performance

Caffeine can help you get more out of your workout. A recent scientific study highlights that caffeine can boost strength and endurance.^[8] Participants who took caffeine could do more bench press repetitions than those who took multi-ingredient pre-workout supplements. You can add that to all the reasons to drink coffee before your workout.?

Better Focus?

Caffeine’s stimulant properties are well-known, but science now suggests that it can enhance focus and alertness without negatively affecting other cognitive areas.^[9]

Heart Health?

A 2021 randomized trial showed that caffeine may benefit heart health by increasing vagal tone, which is part of the body’s system that helps control the heart.^[10] Higher vagal tone is linked to better heart function and protection during exercise. Compared to a placebo, caffeine led to a stronger vagal response after intense cycling. This suggests that caffeine might help support heart health during physical activity.?

Boost Metabolism?

Caffeine helps boost metabolism by increasing resting energy expenditure (REE), which means the body burns more calories at rest. It stimulates the central nervous system, promoting the release of adrenaline, which increases fat breakdown and energy use. In a scientific study, the effect is temporary and lasts for at least 100 minutes.^[11] Caffeine could potentially help with calorie burning and weight management efforts as well.^[12]

The Bulletproof Approach to Caffeine

At Bulletproof, our focus is on helping you optimize your physical and mental performance.? The caffeine in Bulletproof Coffee can fuel your body and brain to tackle your daily to-do list. We carefully select our coffee and lab-test it for mold and toxins to ensure the highest quality. That means you get a delicious tasting clean coffee that supports you without the jitters or crashes often caused by lower-quality beans. ?

Caffeine and Mental Energy

Staying sharp throughout the day can be challenging. Caffeine can help boost your mental energy by stimulating your central nervous system. Caffeine blocks the neurotransmitter that promotes relaxation, making you more alert and focused.^[13] It also enhances the release of dopamine and norepinephrine, improving mood and cognitive function, resulting in sharper mental clarity and sustained concentration.^[14]

Caffeine for Physical Performance

Consider having coffee before your next workout to enhance your energy, focus and metabolism. Caffeine increases adrenaline, which can help improve your physical performance.^[15] Post-workout, caffeine can aid muscle recovery by replenishing glycogen stores faster. It also helps reduce muscle soreness, promoting faster recovery.^[16]

Long-Term Health Benefits of Caffeine

Good news for coffee and tea drinkers: long-term caffeine consumption may offer cognitive benefits, including improved memory and reduced risk of neurodegenerative diseases.^[17] It can enhance metabolism, support fat loss and improve endurance.^[18]

Side Effects and Risks of Caffeine

Caffeine side effects may include anxiety, insomnia, increased heart rate and digestive issues if consumed in excessive amounts.^[19] It may cause dependency, resulting in withdrawal symptoms such as headaches and fatigue.^[20] Long-term overconsumption is linked to high blood pressure, reduced bone density, and increased risk of heart problems for certain people.^[21]

Where to Find Caffeine

Caffeine is found in many different foods and drinks. The most common way to ingest it, though, is in coffee, tea, energy drinks and supplements. ?

Coffee and Tea

There’s caffeine in both tea and coffee in varying amounts. A typical cup of coffee contains around 95 mg of caffeine, while a cup of tea generally has 20-60 mg, depending on the type (black tea contains more than green tea).^[22] Coffee delivers a more substantial, quicker energy boost due to its higher caffeine content, while tea provides a milder, more sustained alertness. The caffeine in tea is often accompanied by L-theanine, an amino acid that promotes relaxation,^[23] offering a smoother, less jittery experience compared to coffee’s more immediate jolt.?

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Energy Drinks and Supplements

Energy drinks can contain high amounts of caffeine, usually around 80-150 mg per serving.^[24] That means potential side effects like jitters or increased heart rate. Be aware that many energy drinks are also loaded with sugar, which can cause spikes in blood sugar levels, contributing to weight gain and other health issues.^[25] Check caffeine and sugar content labels, as too much of either can be harmful. Opting for sugar-free or lower-caffeine alternatives, like a cup of coffee, can help minimize these health risks.?

Caffeinated supplements aren’t much better. A recent study investigated caffeine levels in various dietary supplements in Vancouver, revealing significant differences across product types.^[26] Fat-loss and pre-workout supplements had the highest caffeine content, averaging 221.19 mg and 249.68 mg per serving, respectively. Some supplements exceeded the 400 mg daily limit recommended by Health Canada, posing potential health risks such as anxiety, insomnia and severe reactions. If you decide to take caffeine supplements, do not exceed the recommended daily intake levels to stay safe.

High Caffeine Recipes

Explore some of our favorite high-caffeine recipes designed to maximize energy and focus. From energizing smoothies to high-powered coffee drinks, these recipes may help fuel your mental and physical performance throughout the day.?

Bulletproof Coffee Recipe

Iced Matcha Latte

Bulletproof Whipped Coffee AKA Dalgona Coffee

Keto Iced Protein Shake?

Berry Matcha Smoothie

Coffee Panna Cotta

Low Carb Chocolate-Covered Coffee Beans

Caffeine FAQs

Does Matcha Have Caffeine?

Yes, matcha has caffeine but varies from regular green tea and coffee. Matcha contains about 18.9 to 44.4 mg^[27] of caffeine per gram, which is more than regular green tea, which has 11.3 to 24.67 mg^[28] of caffeine per gram. For comparison, coffee beans contain about 10.0 to 12.0 mg of caffeine per gram. When considering the concentration per gram, matcha has more caffeine than regular green tea and coffee. However, a cup of brewed coffee typically has more caffeine because you use a more significant amount of coffee grounds when brewing a cup. Matcha also has an amino acid called L-theanine. Caffeine and L-theanine together may help support concentration and help with stress.^[29] So, matcha can be a good option for a gentle, sustained energy boost.

Is Caffeine in Decaf Coffee?

Decaf coffee still has some caffeine, but much less than regular coffee. Decaffeination removes most of the caffeine, but not all of it. On average, a cup of decaf coffee has about 2 to 5 milligrams of caffeine, compared to 70 to 140 milligrams in a regular cup.^[30] The exact amount can vary depending on the type of coffee bean and the method used to remove the caffeine. So, while decaf coffee is an excellent option to reduce their caffeine intake, remember that it is not entirely caffeine-free.

What Are Symptoms of Caffeine Withdrawal?

If you’ve skipped your morning coffee, you probably already know caffeine withdrawal can feel less than ideal. Common symptoms include headaches, tiredness and trouble concentrating.^[31] Some people feel irritable, anxious, or depressed when they stop caffeine. Other symptoms might be nausea, muscle pain, or even flu-like feelings. The severity depends on how much caffeine you usually consume. If you’re thinking of cutting back on caffeine, try to do so gradually rather than quitting suddenly to help make withdrawal symptoms milder and easier to manage.

How Much is Too Much Coffee?

For most adults, up to 400 mg of caffeine daily, equivalent to about four 8-ounce cups of coffee, is considered safe.^[32] Consuming more than this can lead to side effects like insomnia, anxiety, increased heart rate and digestive issues. Sensitivity to caffeine varies, and you may experience these effects at lower amounts. Consistently exceeding recommended limits can result in caffeine dependency, withdrawal symptoms, or longterm health risks. Pregnant women, those with heart conditions, or people with anxiety disorders should limit their intake even further to avoid potential complications from excessive caffeine.

Do Coffee Beans Vary in Caffeine Content?

Yes, coffee beans do vary in caffeine content. The variation depends on the coffee bean variety, growing conditions and processing methods. For example, Arabica beans generally contain less caffeine than Robusta beans. Additionally, beans grown at higher altitudes tend to have higher caffeine concentrations due to slower growth. Processing methods, such as roasting, also affect caffeine levels, with darker roasts having slightly less caffeine than lighter roasts. Brewing techniques can even impact the final caffeine content in your cup.