The history of coffee begins in the 14th century in Ethiopia to , where it began to be attributed with stimulating properties. From the Horn of Africa, its use spread to Yemen in the 15th century and from there it spread to the rest of the Middle East and North Africa. It was the trade of Venetian ships with the Middle East that brought coffee to Europe, from where it was introduced to America (Cano-Marquina, Tarin y Cano, 2013).

In Spain alone, 14 billion cups of coffee are consumed each year, with the average weekday coffee consumption being 3.6 cups per day among those over 15. It should be added that 22 million people in Spain drink at least one coffee a day (Ramirez, 2016). These consumption patterns are similar in America and the rest of Europe, with the Nordic countries leading in per capita consumption.

Therefore, taking into account how established caffeinated beverages such as coffee are in the Western diet, the study of their short, medium and long term effects has become of great importance . Analyses and research have been carried out at both psychological and physiological levels.

What does coffee consist of?

One of the main components of coffee, and which gets its name from it, is caffeine. This substance, which we ingest in each cup, is a vegetable alkaloid that acts as an antagonist of the adenosine receptors in the nervous system .

Caffeine prevents the degradation of cyclic adenosine monophosphate by phosphodiesterases, which enhances post-synaptic neurotransmission in the sympathetic nervous system. Because of this, one of the main effects of caffeine in the body is, by increasing the intensity of transmission, to cause an activation in the body (Glade, 2010). Although caffeine is the best known, within a cup of coffee we can find, among others, components such as vitamin B3, magnesium and potassium .

Beneficial effects of its consumption

According to information provided by science over dozens of years of research, it seems that the positive effects of moderate and chronic coffee consumption far outweigh the possible harm it may cause. In the consequences and effects of the consumption of caffeine, other factors are involved that increase the state of alert, besides the substance itself, such as, for example, the personality of the consumer and the hour of the day (moment of the circadian cycle).

Caffeine improves, above all, performance in surveillance and other simple tasks that require sustained attention. It also increases the level of alertness and reduces the feeling of fatigue (both mental and physical), and this effect may be beneficial for sports practice. These effects are especially marked when, due to the situation, the subject’s level of activation is markedly low (night work, driving on a highway with few curves, etc.). Taking into account the latter, the use of caffeine can lead to an increase in safety and efficiency in certain jobs and environments such as driving (Smith, 2002). Moderate consumption has also been associated with a decrease in the incidence of diabetes and liver disease (Cano-Marquina, Tarin y Cano, 2013).

Returning to its relationship with adenosine, in recent years studies have been developed in which the neuroprotective role of caffeine in certain diseases is evaluated . Adenosine itself plays an important role in the control of brain disorders, having inhibitory A1R receptors (which would function as an obstacle to neurodegeneration) and facilitating A2AR receptors (whose blockage would alleviate the long-term damage of various neurodegenerative conditions). Caffeine would come into play by acting as an antagonist of the A2AR receptor, which would favour the phenomenon of synaptic plasticity and, like the other antagonists of this receptor, would act as a cognitive “normaliser”, preventing deterioration and reducing its progression.

This could therefore be a promising start in the study of adenosine A2AR receptor blockers, providing new and diverse therapeutic options for the treatment of the early stages of, for example, Alzheimer’s disease (Gomes et al., 2011).

The bitter side of caffeine

With regard to the harmful effects of caffeine, in Smith’s (2002) review of the subject, he states that these damages only appear under certain conditions. One of these would be when consumed by people with anxiety problems, whose level of activation is already high.

In people not affected by this problem, the negative effects would occur when excessively high amounts are consumed. The ingestion of drinks such as coffee, in these situations, would cause an increase in anxiety and this would lead, for example, to tachycardia, sleeping difficulties, or even a worsening of fine motor control (Smith, 2002). When intake exceeds approximately 300 mg per day, the motor system can be severely activated, the sleep-wake cycle can be disrupted and brain metabolism rates can be generally increased.

Although, as with many other substances, inappropriate caffeine consumption can lead to a variety of problems, there is reason for optimism in this regard. Almost all consumers have a low to moderate intake (50-300 mg per day), at which dose the above-mentioned behavioural effects appear. Despite the fact that there are people who describe coffee, and therefore caffeine, as a socially accepted drug, the brain mechanisms affected by the consumption of this psychostimulant differ greatly from those of other substances of abuse such as cocaine, amphetamines, alcohol, THC and nicotine (Nehlig, 1999).

Why then does this consumption not reach harmful levels?

The area of the brain most related to drug dependence is considered in neuroscience to be the area of pleasure, i.e. the nucleus accumbens. This nucleus is divided both functionally and morphologically into a central area and the cortex area. The mesolimbic system of dopamine, which originates in the ventral tegmental area and ends in the nucleus accumbens, also plays an important role in reinforcing addictive behaviour.

Enough quantities to feel the effects of drugs of abuse such as cocaine, alcohol and others, selectively activate the dopaminergic neurotransmission in the cortex of the nucleus accumbens , which sustains the very high addictive capacity of these substances. In contrast, the consumption of caffeine necessary to activate their properties increases the release of dopamine only in the caudate nucleus without inducing any release in the nucleus accumbens. This selective activation of the caudate nucleus would be related to the stimulating properties of caffeine in psychomotor activity.

On the other hand, caffeine also stimulates the release of dopamine in the prefrontal cortex, which would be consistent with its psychostimulant properties and with the reinforcement of consumption behavior. For caffeine to increase the functional activity of the nucleus accumbens cortex it would have to be consumed in an amount five times greater than the daily average. This high consumption would activate many other brain structures such as most of the limbic and thalamic regions and those related to the extrapyramidal motor system. This would explain the side effects of excessive consumption. As a conclusion to these data, Astrid Nehlig (1999) states that despite the fact that caffeine has some criteria to be considered a drug of abuse, there is a very low risk of addiction .

Finally, taking into account the good capacity of self-regulation by the general population both in the amount to be consumed and in the time of day, the knowledge of the pros and cons of something as usual as drinking a cup of coffee, will favour an even more responsible consumption. In light of the information provided by scientific research, there does not seem to be a more powerful excuse to take a break and drink coffee in the company of friends, family or colleagues than to improve one’s health. All for the sake of well-being.

Bibliographic references:

  • Cano-Marquina, A., Tarín, J. J., & Cano, A. (2013). The impact of coffee on health. Maturitas, 75(1), 7-21.
  • Glade, M. J. (2010). Caffeine – not just a stimulant. Nutrition, 26(10), 932-938.
  • Gomes, C. V., Kaster, M. P., Tomé, A. R., Agostinho, P. M., & Cunha, R. A. (2011). Adenosine receptors and brain diseases: neuroprotection and neurodegeneration. Biochimica et Biophysica Acta (BBA)-Biomembranes, 1808(5), 1380-1399.
  • Nehlig, A. (1999). Are we dependent upon coffee and caffeine? A review on human and animal data. Neuroscience & Biobehavioral Reviews, 23(4), 563-576.
  • Ramírez, E. (2016). The presence of coffee in the life of the Spanish increases – Retrieved from:
  • Smith, A. (2002). Effects of caffeine on human behavior. Food and chemical toxicology, 40(9), 1243-1255.