Caffeine and its effects on the human body

Caffeine and its effects on the human body

Caffeine is one of the most consumed substances in the world and is found not only in coffee, but also in tea leaves, guarana berries, cocoa beans, and many soft drinks, chewing gum, and medicines. Despite massive consumption, caffeine is more of a habit than an addiction. Recently, it has been scientifically studied for its potentially health-promoting effects, such as protection against oxidative stress in Alzheimer's disease. Rodak et al. (2021) have provided an overview of the current state of knowledge in the journal Nutrients. The following information is taken from this article.

Caffeine – General information

Caffeine, chemically known as 1,3,7-trimethylxanthine, is a white, odorless powder with a slightly bitter taste that is found in over 60 plant species. It is extracted from green coffee beans, tea leaves, and kola nuts, or produced synthetically. After ingestion, caffeine is rapidly absorbed by the small intestine, crosses the blood-brain barrier, and is metabolized primarily in the liver.

Genetics and caffeine

Individual response to caffeine may be genetic. Various genes affect the metabolism of caffeine, particularly the CYP1A2 gene. People with different genotypes of this gene metabolize caffeine at different rates, which affects their response to caffeine.

Effects on receptors

Caffeine exerts most of its biological effects by blocking adenosine receptors, which leads to an increase in cAMP concentration in cells. At higher doses, caffeine also acts as an agonist of ryanodine receptors and stimulates the release of calcium from the endoplasmic reticulum.

Caffeine toxicity

Although moderate intake of caffeine is considered safe, a dose of over 300 mg at a time can cause symptoms of caffeine poisoning. The severity of side effects is dose-dependent, and it is recommended not to consume more than 400 mg of caffeine daily to avoid health risks.

Caffeine and various systems in the human body

Central nervous system (CNS)

Caffeine interacts primarily with the central nervous system by blocking adenosine receptors. This blockade leads to a stimulating effect that can have a positive effect on cognition, alertness and general neurological performance. Systematic studies show that caffeine can have neuroprotective effects in neurodegenerative diseases such as Alzheimer's and Parkinson's. It significantly reduces the risk of developing Alzheimer's dementia, especially with regular consumption of moderate amounts of coffee. A preventive effect is also being discussed for Parkinson's, with caffeine appearing to reduce the incidence of the disease without, however, improving motor symptoms.

Cardiovascular system

The effect of caffeine on the cardiovascular system is complex. It can increase blood pressure and affect heart rate in the short term. However, these effects are usually temporary and wear off with regular consumption. Regular caffeine intake is associated with a potentially lower risk of certain heart diseases, but excessive consumption can increase the risk of arrhythmias and other cardiovascular problems. Research shows that regular consumption of caffeinated coffee is associated with lower mortality, suggesting possible protective effects on the cardiovascular system.

immune system

Caffeine has anti-inflammatory properties and affects the function of immune cells such as monocytes and macrophages. It can modulate the release of pro-inflammatory cytokines and thereby reduce inflammatory processes in the body. These immunomodulatory effects of caffeine may play a role in the treatment and prevention of chronic inflammation and certain autoimmune diseases.

Digestive system

The effects of caffeine on the digestive system are complex. On the one hand, caffeine can increase stomach acid production and lead to stomach discomfort. On the other hand, it has antioxidant and anti-inflammatory properties that can have a protective effect. Regular coffee consumption has been linked to a reduced risk of certain types of liver disease, including cirrhosis and hepatocellular carcinoma. The role of caffeine in preventing gastrointestinal disease and promoting liver health is an important area of ​​research.

Metabolism and endocrine system

Caffeine can affect metabolism by increasing lipolysis and thermogenic activity, leading to increased fat burning and increased energy expenditure. These properties make caffeine a popular ingredient in many weight loss products. Additionally, research shows that caffeine can affect insulin sensitivity and play a role in regulating blood sugar levels, which is especially important for people with diabetes or metabolic syndrome.

Musculoskeletal system

Caffeine can improve muscle performance by increasing the release of calcium from the sarcoplasmic reticulum, thereby enhancing muscle contractions. This effect makes caffeine a popular supplement, especially in sports nutrition. There is also evidence that caffeine can reduce muscular pain after exercise and shorten recovery time.


Caffeine is a complex substance with diverse effects on the human body. While it offers numerous benefits in moderate amounts, high doses can lead to health problems. Research into caffeine will continue to provide important insights into its effects, both for medical science and for everyday consumption.

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