Is caffeine bad for you?

Let’s start with the basics: what is caffeine?

Caffeine is perhaps the world’s most popular stimulant. For example, you can find it in coffee beans, tea leaves and guarana.

There are claims that caffeine is bad for you, with some studies linking consumption with various health benefits and health risks. However, according to some research, moderate consumption, i.e. 3 to 4 cups daily, may reduce the risk of cardiovascular disease, type 2 diabetes, liver cancer, and Parkinson disease. What’s more, research has also found a link between moderate coffee consumption and a longer life span.(1)

How is caffeine absorbed by your body?

A scientific term referred to as “half-life” can be useful to understand the effects of caffeine on our body. Half-life is how long it takes the human body to eliminate 50% of the caffeine from itself.

Of course, the amount of time can vary significantly depending on individual factors, which include gender, age, weight, liver health, medication status and pregnancy. In the general healthy adult population, the average half-life of caffeine is around 4 hours. Although, this can range from 2 to 8 hours.

The human body absorbs caffeine around 45 minutes after consumption. Depending on the individual, once the body absorbs it, blood levels can peak anywhere between 15 to 120 minutes afterwards.

As you might know, you can commonly find caffeine in many beverages. One of the most popular is coffee and that’s what we’re going to focus on in this article.

What is actually coffee and where does it come from?

You probably know that coffee is brewed from the roasted and ground beans of the tropical evergreen coffee plant. You can find the beans inside the plant’s fruit and it takes about a year for the beans to mature and ripen until people can harvest them. The plants require mild temperatures, sufficient shade and lots of rain. For that reason they can only grow productively in temperate areas of the world.

Roasted beans have darkly coloured, bitter, and slightly acidic properties. They have a stimulating effect on humans, primarily due to there being caffeine in coffee beans. Furthermore, one shot of coffee or a regular espresso contains around 80mg, while a 200ml cup of filter coffee contains about 90mg of caffeine.

The origins of coffee

Coffee was gradually introduced into Europe throughout the 16th and 17th centuries. Many accounts are recorded of its approval as a religious, political, and medical concoction. However, by the end of the 17th century, coffeehouses were flourishing across Britain, the British colonies in America, and continental Europe.

Some believe that the beverage originated either in Yemen or Ethiopia. One of the many tales about the discovery of coffee takes place around 850 AD in Ethiopia. Kaldi, a goat farmer, was puzzled by the strange behaviour of his flock. He supposedly sampled the berries on which the goats were feeding on and experienced a sense of exhilaration. Thus, proclaiming his discovery to the world.

Whatever the origin of coffee, its stimulating effect undoubtedly made it so popular. For a lot of people, coffee is an integral part of their daily routine, in order to start the day right. But why is it so popular if there are claims that caffeine is bad for you?

Is caffeine bad for mental alertness?

One of the biggest reasons for the popularity of caffeine is its perceived ability to ‘wake you up’. Many people drink coffee, especially in the morning, with the objective of increasing mental alertness. Let’s look into this a little further.

A study investigated the effects of caffeine consumption on medium/high and non/low consumers following overnight abstinence. They found mental alertness improved in medium/high consumers but not in non/low consumers. It’s also worth noting that non/low consumers experienced decreased sleepiness. However, this was accompanied by an increase in anxiety and restlessness, which indicates that it might be bad for you if you suffer from caffeine sensitivity.(2)

Moreover, some research suggests that caffeine does not boost mental alertness above baseline levels in regular consumers. As a matter of fact, in regular consumers, caffeine withdrawal (overnight), has a counteractive effect, lowering mood and alertness. Hence, consuming more caffeine reverses these withdrawal symptoms, although it might not surpass baseline levels.(3)

This is what’s referred to as a “caffeine tolerance”, which people can develop if they consume it regularly. Therefore, once a person stops, withdrawal symptoms begin. In general, symptoms include headaches, fatigue, irritability and low mood.

Is caffeine bad for athletic performance?

Substances including caffeine are often at the forefront when it comes to legal ergogenic aids and athletes are always on the lookout for ways to improve performance.

During exercise, caffeine may help to fight fatigue. This is because it has the ability to increase the use of fat for fuel, which is beneficial, especially for endurance sports because the glucose stored in muscles lasts longer. Therefore, it increases the time it takes for muscles to reach exhaustion. Researchers looked at the effects of caffeine on athletic performance. In the studies, doses of 5mg per kg of body weight of caffeine improved endurance by up to 5% when consumed 1 hour prior to exercise.(4)

Another factor contributing to improved performance could be its ability to reduce perceived exertion during exercise by up to 6%, hence making workouts feel easier. A 6% decrease may seem insignificant but it's important to mention that athletes look for any marginal gain to improve performance. The reduction in perceived exertion could be because caffeine blocks the receptors of a neurotransmitter called adenosine, and this increases levels of other neurotransmitters in the brain that regulate energy levels, including dopamine.(5)

It’s worth noting that any ergogenic effect experienced from caffeine is not going to make up for a poor diet or lack of training consistency.

Robusta vs Arabica: Which beans have more caffeine?

If you ask your friends to name their favourite type of coffee, you’ll probably hear varieties or flavours, such as latte, instant coffee, iced coffee, decaf, or “with milk and sugar.” However, coffee goes a little deeper than this!

Firstly, let’s consider the types of coffee beans. There are two predominant types of coffee beans: Arabica and Robusta. Arabica beans are the most popular because of their quality. Generally speaking, arabica coffee is smooth and flavourful with more acidity. Robusta beans are hardier and easier to grow, so they’re less expensive to buy.

One of the main differences between these two beans is the caffeine content. The content of the Arabica bean is roughly half that of the Robusta bean. The Robusta bean will have up to 2.5% caffeine whereas the Arabica will generally not have more than 1.7%. This is why Robusta beans are particularly popular in Italy as an espresso!

Light, medium or dark roast?

If you’re a regular coffee drinker you would have heard about light, medium and dark roasts, but if you’re new to this, let’s introduce you to them! The colour of the beans is the easiest and most common method to identify them:

• Light roasts have a high acidity, light flavour and light aroma.
• Medium roasts have a stronger flavour, but not overpowering and a slight roast taste.
• Dark roasts have a strong aroma and flavour, noticeable bitterness, and are less acidic.

Technically, the roasting process does not affect the caffeine content of coffee beans. So, light, medium, and dark roast beans all contain the same amount.

What about the different coffee brewing methods?

Brewing methods can indeed have a major impact on both flavour and strength:

• Drip coffee contains around 63mg of caffeine per 100ml. Hot water drips through coffee grounds, which picks up the coffee’s flavour and aroma.
• Pour-over is essentially drip coffee without the machine. You hold the coffee filter (containing ground coffee) over your cup, and slowly pour hot water directly into the filter. It typically contains 75mg caffeine per 100ml.
• French press is when large coffee grounds are steeped in hot water. You press down on the plunger after a few minutes, and rich coffee is forced out. The French press can contain up to 90mg of caffeine per 100ml.
• Cold brew is when no heat is used to create coffee. Ground coffee is steeped in cold or room temperature water for 12 to 24 hours. If brewed for 24 hours, a cold brew contains around 110mg of caffeine per 100ml.
• Espresso is when pressurised water is forced through compacted, fine coffee grounds, producing a richer, thicker coffee. Espressos are the strongest, containing 270mg of caffeine per 100ml! This is why they’re served as a 25 to 30ml shot.

It’s important to note that because we are all different, it's no surprise that caffeine can interact differently depending on the individual. If you experience symptoms of anxiety, perhaps it might help switching from coffee to matcha. Matcha tea provides a much more gentle energy boost compared to the caffeine in coffee.

Related readings

• How long does caffeine stay in your system?
• Does herbal tea have caffeine?