Caffeine: A Natural Stimulant and Its Effects on the Body

Caffeine comes to the rescue when you lack energy during training or want to push for a personal best. It's also helpful when you have a lot of work or studying ahead, or need an extra boost after a sleepless night. However, these are not the only benefits of using caffeine. Regardless of whether you consume it in the form of your favorite coffee or a pre-workout supplement, it offers much more than just an "energy kick."

Caffeine: A natural dose of energy

Caffeine is an organic chemical compound obtained from over 60 plant species, including coffee beans, cocoa, and tea leaves, but it can also be obtained through chemical synthesis [1]. Caffeine is a natural stimulant and acts by stimulating the brain and central nervous system (CNS), helping to maintain alertness and prevent fatigue [2].

Caffeine vs. caffeine anhydrous

Caffeine is a compound found naturally occurring in coffee and tea leaves. Caffeine anhydrous, on the other hand, is a highly concentrated form of caffeine. It is obtained in laboratories by removing water molecules from the molecule. It forms a white, crystalline powder with a concentrated caffeine content [3]. Caffeine anhydrous is added to, among other things, medications, dietary supplements, and energy drinks, because such processing allows manufacturers to more precisely determine its doses in the product.
 

One compound, several names

Caffeine is also known as theine - from tea, mateine - from yerba mate, and guaranine - from guarana. Chemically, it is the same substance, differing only in its source [4].

How does caffeine work?
 

After consumption, caffeine is rapidly absorbed from the intestines into the bloodstream, and peak concentrations are reached after 30-120 minutes [1]. From there, it travels to the liver and is broken down into compounds that can affect the functioning of various organs, but the main effect of caffeine is on the brain [5].
 

Caffeine works by blocking the action of adenosine, a neurotransmitter that has an inhibitory effect on the CNS - it "relaxes" the brain and causes feelings of fatigue [5]. During the day, adenosine levels rise, and caffeine helps to stay alert by binding to adenosine receptors in the brain without activating them. In addition, caffeine can raise blood adrenaline levels and increase the activity of dopamine and norepinephrine [2].

Did you know that...

Caffeine from one cup of coffee can enter the bloodstream in as little as 20 minutes? [6]

How does caffeine affect the body?

Scientific research suggests that caffeine may affect:

Cognitive functions

Caffeine helps not only athletes - it can also be helpful for mental work. Thanks to caffeine, concentration, memory, reaction time, and attention increase, and drowsiness and mental fatigue decrease [6-8]. Importantly, it can improve cognitive function even after a sleepless night [9] - however, it should be remembered that it is not possible to suppress fatigue in the long run.
 

In 2017, an extensive review of 25 studies by the US Institute of Medicine was published [10]. The work concerned the use of caffeine among 653 participants during prolonged military operations. The results suggest a beneficial effect of caffeine consumption on cognitive function in sleep-deprived individuals. Participants experienced improved attention and alertness, reaction time, problem-solving, and reasoning.

Energy levels and stimulation

Caffeine has a stimulating effect on the body and can delay fatigue, which is why it is a popular ingredient in so-called pre-workouts. Caffeine can improve subjective assessment of exertion, and improve aerobic endurance, anaerobic capacity, sprint speed, muscle endurance, muscle strength, and agility. These effects occur in many different sports [1,11-13].

Metabolism and fat burning

Caffeine can be helpful in weight loss because it potentially:

* speeds up metabolism (by up to 11%),

* accelerates fat burning (by up to 13%),

* affects the increase in resting metabolic rate,

* increases energy expenditure by about 100 kcal per day.

Using caffeine alone for weight loss is a poor strategy (e.g., in popular fat burners). It accounts for a fraction of the several components of weight loss - the most important is a calorie deficit in the diet, so it is best to treat it as an adjunct in this process.

Mood and motivation

An extensive review of scientific research from 2016 suggests that moderate caffeine consumption may have a positive effect on mood and motivation [14]. During exercise, adenosine is released in the body, which affects a decrease in the release of dopamine - the so-called "reward hormone" [14,15]. Taking caffeine before or during exercise maintains dopamine release, potentially maintaining mood and motivation for further hard work.
 

Prevention of some diseases

Scientific research suggests that regular coffee drinking (100-400 mg caffeine/day) may reduce the risk of: [16-19]

* heart disease by 16-18%,

* heart attack by 20%,

* type 2 diabetes by 30%,

* gout by 40% in men and 57% in women.

In addition, consuming 3 cups of coffee a day for just 3 weeks can increase the amount and activity of beneficial gut bacteria [20].

How much caffeine per day?

The safe dose of caffeine for an adult is up to 400 mg per day. Based on current scientific research, it can be concluded that a safe and well-tolerated daily dose is 3 mg/kg body weight [21].

Caffeine use before training

To experience the benefits of using caffeine during training, it is worth consuming it 30-60 minutes before starting exercise. The portion should be adjusted to your preferences and feelings. It is recommended to start with 100 mg/200 mg and observe the body's reaction. It is not worth "throwing yourself" immediately at the popular 400 mg - especially if you don't drink coffee every day and have never used a product with pure caffeine. Instead of enjoying the workout, you may feel unwell (headache, nausea), and even experience anxiety. Focus on the quality of caffeine, not the quantity - and remember, caffeine won't do the workout for you.

Regular intake of high doses of caffeine can lead to changes at the chemical level in the brain - brain cells may produce more adenosine to compensate for those blocked by caffeine [22]. So to continue to achieve stimulation, you need to take more caffeine. This leads to "tolerance" to caffeine and it no longer brings any more effects. Therefore, it is not recommended to use caffeine for every workout. Therefore, it is not recommended to use caffeine for every workout, but only occasionally.

Sources:

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[2] Ferré S. An update on the mechanisms of the psychostimulant effects of caffeine. J Neurochem. 2008 May;105(4):1067-79. doi: 10.1111/j.1471-4159.2007.05196.x. Epub 2007 Dec 18. PMID: 18088379. .x;

[3] Trexler ET, Smith-Ryan AE, Roelofs EJ, Hirsch KR, Mock MG. Effects of coffee and caffeine anhydrous on strength and sprint performance. Eur J Sport Sci. 2016 Sep;16(6):702-10. doi: 10.1080/17461391.2015.1085097. Epub 2015 Sep 22. PMID: 26394649; PMCID: PMC4803635. 

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[7] Nehlig A, Daval JL, Debry G. Caffeine and the central nervous system: mechanisms of action, biochemical, metabolic and psychostimulant effects. Brain Res Brain Res Rev (1992) 

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