All About Caffeine in Coffee: Caffeine Levels, Benefits, and Low-Caffeine Options

All About Caffeine in Coffee: Caffeine Levels, Benefits, and Low-Caffeine Options

What is Caffeine?

Caffeine is the common name for 1,3,7-trimethylxanthine – a chemical that most of us are familiar with – at least how it makes us feel! Caffeine is the most-consumed psychoactive stimulant worldwide.[1] But despite consuming it almost every day (maybe multiple times daily), there are some widespread myths and misunderstandings about caffeine.

What is caffeine? What does caffeine do to the body? Is caffeine healthy or bad for you? Where does caffeine come from? Why do some plants make it? Who should avoid caffeine? Is caffeine harmful? Is it okay to consume caffeine at night? Is there a limit to how much caffeine we can consume? What is decaf coffee, and where did the caffeine go? What about low-caf coffee, what’s the story about that? 

We’re going to get a bit scientific so we can reach a solid understanding of our favourite molecule for practical purposes. With accurate information, we can equip ourselves to make choices and navigate life in a way that works best for us. And since caffeine is a fairly strong psychoactive drug, this knowledge can help us understand how it affects each of us personally, and enjoy caffeine – and its numerous beneficial effects – while avoiding any potential negatives.

But before we get too scientific, let’s get straight to the good stuff and take a look at the relationship between caffeine and coffee.

Chiccodoro, CC BY-SA 2.0 <>, via Wikimedia Commons

Caffeine in Coffee

Caffeine is naturally present throughout the coffee plant, including in its seeds (which we know as coffee beans). It’s soluble in water, meaning that when we pass water through the ground coffee, some of the caffeine is drawn out, along with the delicious flavours, into the cup. The amount of caffeine that comes through depends on a few factors, including the extraction method, a.k.a. the brewing method (we will dive into diverse brewing methods in an upcoming article series).

How Much Caffeine is in Coffee?

It’s difficult to give an exact answer to this question because there are many variables at play. Instead, we can provide approximate ranges of caffeine levels in different coffee extraction methods (for 100% Arabica beans).

Note that adding milk, sugar, or more water after brewing (as in an Americano) does not affect the amount of caffeine extracted from the coffee!

  • Espresso and espresso-based drinks (single shot): ~ 60 mg
  • Espresso and espresso-based drinks (double shot): ~80 to ~120 mg
  • Brewed coffee (american-style): ~100 mg per 250 mL cup
  • Filter coffee (Aeropress, V60, Chemex, etc.): ~80 to 150 mg, depending on the amount of coffee beans used and the serving size
  • Iced coffee: ~80 to 150 mg, again depending on the ratio of coffee:water used and the brewing time

The above levels refer to Arabica coffee, as found in most specialty shops. There are other types of coffee though:

  • Robusta coffee can have as much as twice the caffeine of Arabica coffee, so you would double the amounts given above to be safe
  • For blends of Arabica-Robusta, it would fall somewhere in the middle of that range
  • Low-caf coffee: From 30% to 50% of the caffeine levels listed above
  • Decaf coffee: ~1 to ~5 mg per coffee (i.e., not zero, but very low)

Caffeine in Coffee vs Tea

Tea actually contains more caffeine than coffee by weight, but we tend to use much more coffee per cup (~15 to 20 grams) than tea (usually about 4 grams). So, a cup of coffee generally has more caffeine than a cup of tea. Black tea generally has more caffeine than green tea, and other “teas” such as rooibos and herbal infusions don’t contain caffeine at all.

Sometimes, people say that “tea doesn’t contain caffeine; it contains theine.” This is… false!

Theine is just another name for caffeine – the exact same psychostimulant found in coffee. However, tea also contains another important compound, L-theanine, a molecule with effects that promote a state of “calm alertness.” L-theanine has been shown to have synergistic effects with caffeine, making the overall stimulating effect of tea somewhat less-jolting, smoother, longer-lasting, and more calm

Caffeine in Cacao

Cacao also contains caffeine! However, it also contains another biologically active compound called theobromine. This powerful molecule also has stimulant properties, due to a similar mechanism of action as caffeine. However, the effect is milder and takes much longer to kick in, meaning a strong hot cacao will also give you less of an immediate ‘jolt’ than caffeine. Interestingly, a small percentage of caffeine is broken down into theobromine in the body, meaning the body makes it as it metabolises caffeine, whether consumed in the form of coffee, tea, cacao, or another source.

Decaf Coffee and Low-Caf Coffee: Two Popular Ways to Drink Coffee While Limiting Caffeine Intake

Whether for personal preference or health reasons, some people love a good coffee but want to avoid caffeine.

What is Decaf Coffee?

Decaffeinated coffee – decaf for short – is coffee that has had its caffeine removed. There is no coffee that’s naturally decaf, although there are some decaffeination methods that are considered “natural” as they use only water or naturally occurring chemicals. If you’re interested, we explain decaffeination methods in another article (coming soon).

Why do People Hate on Decaf?

Decaf has had a bad rep in the past, largely due to a logic that went something like this:

“Why waste good coffee and destroy its flavour by decaffeinating it?”

While this reputation may still follow decaf around in some circles, the logic has since changed and nowadays there are many very good decaf specialty coffees. Consumer demand for decaf has increased hugely over the past years, and is expected to keep growing, largely due to the millennial generation looking to cut down on caffeine.[2]

So, the new approach to decaf looks more like this:

“People want decaf coffee, and they want it to be good, so let’s use better coffees and perfect the decaf methods!”

When the decaffeination process is done well, starting with high-quality specialty coffee beans, the coffee retains almost all of its natural flavour profile, and can be used to make excellent, tasty drinks, from lattes to filter brews using a V60 or Aeropress.

Is Decaf Really Zero Caffeine?

Contrary to popular belief, there actually is some caffeine in decaf coffee. It’s not really possible to get the caffeine down to zero without destroying the bean, but luckily this isn’t an issue for most people. If you’re caffeine sensitive, it’s unlikely that 2 mg of caffeine will give you any negative effects. However, if you’re allergic to caffeine or must avoid it entirely, then it’s important to know that decaf coffee does have a tiny amount of caffeine.

What is Low-Caf Coffee? Coffees Naturally Low in Caffeine

For the purists among us, we’ve got good news for you. A relatively new player has emerged on the specialty coffee scene. There are a couple coffee varietals which naturally have lower levels of caffeine than their more-common counterparts – generally about 30% to 50% (i.e., one-third to one-half of the caffeine).

These coffees are rarer because of the effect of caffeine in protecting the plant, so they’re generally harder to grow well, and thus harder to come across.

At Abyss, we’re roasting an excellent coffee coming from Brazil, of the varietal Aramosa. This coffee has about half of the caffeine of our other Arabica coffee offerings, meaning that a cup might contain just ~30 to 80 mg of caffeine, depending on the brewing method. Since the low-caf varietals have not been subjected to any decaffeination processing, they have naturally rich flavour profiles with the same depth you expect from any specialty coffee.

Our Brazil Daterra low-caf reserve is becoming increasingly popular, and is a must-try for any specialty coffee lover looking to limit their caffeine intake or just to try something new! 

Abyss Coffee Brazil Daterra Low-Caf Reserve roasted coffee beans

Great. Now that we understand the relationship between caffeine and coffee, let’s take a closer look at caffeine – what it is, how caffeine affects our bodies, how long it lasts, and where it comes from!

Caffeine Structure and Chemistry

Caffeine is an alkaloid - a class of nitrogen-containing substances that are produced by plants/animals/bacteria/fungi. The chemical formula of caffeine is C8H10N4O2, arranged into the following molecule:

Caffeine molecular structure 


Caffeine is produced by a few different plants, most famously including coffee, tea, yerba maté, gauraná, and cola (kola nut).

Why Do Plants Make Caffeine in the First Place?

As coffee lovers, we’re obviously thankful for the seemingly random mutations that occurred over millions of years, separately in different plants, leading them to produce such a powerful molecule. But why would such a thing even happen? Caffeine is produced by enzymes ‘stitching together’ chemical building blocks, a process that occurs in all plants. The fact that coffee and cacao developed this pathway using separate enzymes indicates that caffeine evidently served a useful purpose.[4]

But was this just for us? Of course not! Recently, a few reasons why plants came to synthesise caffeine have been revealed:[4]

  1. When leaves fall off the plant, the caffeine is absorbed into the soil and may prevent other plants from thriving, thereby protecting themselves by eliminating proximal competition for nutrients in the soil.
  2. Caffeine is toxic to many insects, and some even have taste receptors to prevent them from eating caffeine-containing plants. So it also acts as protection against insects/pests harming the plant.
  3. Caffeine may also help coffee plants propagate by pollination, as it’s been shown that bees actually get a little caffeine kick through the pollen. This likely serves to make them more likely to remember the plant and come back, also potentially helping them reach the next flower with that extra motivation.

So, as the strange species we are, we’ve developed elaborate methods of preparing delicious beverages containing a natural insecticide. But it’s interesting to link the purposes of caffeine in plants to its effects on our physiology and behaviour, which we dig into in the next section.

Caffeine Effects: How Does Caffeine Affect the Body?

Many common drugs we use are derived from chemical compounds naturally produced by plants. Common examples include:

  • Caffeine (tea, coffee, cacao, mate, guarana)
  • Acetylsalicylic acid/aspirin (derived from the bark of the willow tree)
  • Many antibiotics (derived from compounds produced by bacteria/fungi)
  • Opioid painkillers (derived from resin of the opium poppy plant)

Drugs usually affect us due to their resemblance to chemicals found naturally in the body. They might have the same size, shape, and charge as a molecule naturally present in our body, or they may fit perfectly into biological receptors.

In the case of caffeine, its effect is due to its resemblance to adenosine. Adenosine is a naturally occurring compound that modulates our wakefulness. When adenosine is present in high concentrations, we feel drowsy, signalling that it might be time to rest and recharge.

When we ingest caffeine, it sneaks right in and attaches to the receptor for adenosine. You can imagine it like caffeine parking its car in adenosine’s garage. While it’s there, adenosine can’t do its thing, meaning that it won’t be making us feel drowsy or sleepy.

So, caffeine does not actually give us energy, but rather temporarily prevents us from feeling drowsy!

Positive Effects and Potential Health Benefits of Caffeine

The main effects of caffeine include:[5]

  • Increased alertness and vigilance
  • Faster reaction time
  • Improved attention
  • Increased arousal and enhanced mood
  • Possibly decreased anxiety (in low doses; the opposite tends to be true for very high doses)

In addition to these cognitive effects, caffeine exerts other physiological effects, both short-term and long-term:

  • Increases blood pressure through vasoconstriction (narrowing of blood vessels)
  • Increases metabolic rate (calorie-burning)
  • Boosts muscular endurance and power output, acting as a performance enhancer. Thus, it can be used as an aid for physical activity.
  • Increases cortisol secretion, further helping us feel alert (but this effect appears to get toned down in chronic caffeine consumers)
  • Appears to play a role in lowering the risk of developing Parkinson’s and Alzheimer’s diseases, and/or in slowing cognitive decline[6]
  • Can help with headache pain
  • Most sources of caffeine – including coffee, tea, and cacao – are full of antioxidants

How Long Do the Effects of Caffeine Last?

It’s pretty obvious to coffee drinkers that the effect of caffeine eventually wears off. The length of time a drug affects us is related to how quickly it’s broken down in the body, also known as its half-life.

Using the example of the car garage we used above, this time we need to imagine a whole parking garage with 1000 parking spots. When we drink a coffee, 1000 little caffeine cars rush into the garage, bullying out any adenosine cars currently parked. Over time, as caffeine is broken down, a few of caffeine’s cars start to leave the garage. As they do, adenosine’s cars enter again to occupy their normal spots. This shift happens in an exponential way – first quickly, then slower until the last caffeine car leaves the garage. This is not unique to caffeine, but is a regular trait of human drug metabolism. The term half-life refers to the time it takes for the drug concentration to decrease by half.

In healthy individuals, the half-life of caffeine is about between 3 and 7 hours. It can vary widely between people, based on age, liver function, any medications you're taking, tobacco smoking, and pregnancy.

Okay, so caffeine lasts 3 to 7 hours?

It’s not that simple, no. In 3 to 7 hours, only half of the caffeine is left in your system. In another 3 to 7 hours, half of that (i.e., 25%). And so on. So, for an average healthy adult, caffeine will be pretty much gone from the body in somewhere between 18 and 24 hours. The graph below shows an approximation of the elimination half-life of caffeine, for a few different hypothetical profiles:

Caffeine elimination half-life curves for different profiles

While caffeine is present in the body, it is still exerting its effect blocking adenosine. But of course, when it reaches relatively low concentrations, there are plenty of adenosine receptors open for adenosine to attach and make you drowsy. So it’s not an all-or-nothing effect, but rather a curve – from being very alert to eventually being able to feel naturally drowsy.

Caffeine in the Evening

You’ve most likely heard recommendations to avoid caffeine in the evening. That’s because of its well-documented impacts on sleep quality, and because of its half-life. If you have an afternoon coffee, let’s say at 6 p.m., and then go to sleep at midnight, at least 25% of the caffeine will still be present in your body. Does that mean you won’t be able to sleep? For some people yes, but for many, no, they might sleep just fine.

However, some research studies have demonstrated that caffeine can negatively alter sleep quality and/or promote sleep deprivation, even when consumed as early as 7 am.[7],[8] Luckily, other studies suggested no real impact of caffeine on sleep or self-reported measures of sleep quality (people’s reports of how rested they feel), even when consumed in the afternoon![8] Unfortunately, we still don’t have a crystal-clear answer here; finding the “truth” is confounded by the almost limitless other factors that can influence sleep quality.

Our suggestion is simple:

  1. If you tend to fall sleep relatively quickly, and feel refreshed in the morning, despite drinking coffee later in the day, you’re probably just fine doing what you do.
  2. If you notice that you have troubling falling sleep, can’t sleep at all, or frequently wake up feeling exhausted, then consider stopping all caffeine intake by noon, or earlier if possible – i.e., coffee only in the morning.
  3. If you find that you get noticeably agitated or jittery (physically or mentally) when you drink coffee, and that feeling stays with you for a large part of the day, and you have trouble sleeping, you’re probably caffeine sensitive. It could be better for you to limit coffee to one cup in the morning, or opt for decaffeinated (decaf) or low-caffeine (low-caf) coffee.

We are going to write about how to time your coffee habit to match with your circadian rhythm in another post in the near future.

Caffeine Side Effects

There are two sides to every coin, and although we love caffeine for its performance-enhancing effects and cognitive boost, it does have its side effects. Some people may not notice these at all, while caffeine-sensitive individuals may have nightmares about even touching a cup of coffee.

Side effects of caffeine are generally mild, but they do increase with dose. If you find you’re experiencing these in a way that’s unpleasant, consider cutting down on caffeine or swapping out one of your coffees for a decaf or low-caf! Potential side effects generally include:

  • Nervousness, restlessness, or anxiety
  • Insomnia or sleep disruptions
  • Racing heart rate
  • Digestive upset, acid reflux, particularly when drinking coffee on an empty stomach
  • Muscle twitching
  • Dizziness

Caffeine Dependence and Withdrawal

Caffeine is psychologically habit-forming, and the body can experience withdrawal symptoms for the first few days or weeks after stopping caffeine. These could include:

  • Difficulty concentrating
  • Drowsiness and fatigue
  • Irritability
  • Headaches
  • Muscle aches, stiffness, and soreness

Who Should Avoid Caffeine?

We share the popular opinion that caffeine – especially when ingested through natural sources, such as coffee, tea, and cacao, is an enjoyable and beneficial part of a healthy diet and lifestyle.

However, some people might need to avoid caffeine. People with liver disease or problems with liver enzyme levels may become particularly sensitive to caffeine as it becomes harder (and slower) for the body to break down. Pregnant women are advised to limit caffeine intake to low levels (under 200 mg per day; ~2 cups of coffee), as it might increase the risk of low birth weight[9]; however, this is also disputed, with some saying it’s relatively unlikely to cause harm to the baby.

There’s another category of people – let’s call them coffee aficionados. Maybe you love the effect of caffeine, but only in the morning, or only up to one cup. After that you start to feel nauseous, anxious, or can’t sleep later at night. BUT – you just love the taste so much. The latte always goes with the work, a takeaway on the way home, coffee and cake in the afternoon. Whatever the reason, you want a coffee – a good coffee – without the effect of caffeine. If that’s you, we recommend experimenting with low-caf and/or decaf coffees, to continue enjoying your coffee rituals without overdoing your personal caffeine limit!


We’ve learned that the story of caffeine is a lot more complex than just “waking us up.” Caffeine is a natural compound that has many demonstrated health benefits, and its effects on cognitive enhancement may be the main reason some people drink coffee. However, advancements in decaf methods and the availability of low-caf varietals have made it possible for those who are caffeine-sensitive or otherwise want to limit caffeine to keep enjoying delicious specialty coffee. While many of the health benefits of coffee have been directly related to caffeine, decaf and low-caf coffee are still packed full of healthy polyphenols, a class of antioxidants with numerous health benefits.


  1. Caffeine - StatPearls - NCBI Bookshelf 
  2. Decaf coffee: why is it growing in popularity?
  3. File:Caffeine.svg - Wikipedia
  5. A review of caffeine’s effects on cognitive, physical and occupational performance - ScienceDirect
  6. Can coffee consumption lower the risk of Alzheimer’s disease and Parkinson’s disease? A literature review - PMC
  7. Effects of caffeine on sleep quality and daytime functioning - PMC 
  8. The impact of daily caffeine intake on nighttime sleep in young adult men | Scientific Reports 
  9. Moderate daily caffeine intake during pregnancy may lead to smaller birth size | National Institutes of Health (NIH) 
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