Caffeine has been gaining popularity recently, with scientific studies backing its effects. How can it benefit health, and when does it become harmful? Let’s delve into the details.

Benefits of Caffeine

Caffeine often raises concerns. Since childhood, many of us have been told that drinking too much coffee is harmful. However, the first study proving the positive effects of caffeine on performance (in the context of aerobic exercise) was conducted back in 1978. Since then, coffee has remained an active subject of research.

Scientists have yet to determine whether caffeine acts independently or whether its effects are due to the combination of caffeine and its metabolites. Nevertheless, its benefits have been confirmed. The most recent large-scale research on this topic is the work of J.H. Wilmore and D.L. Costill on sports physiology (2001), which corroborates some previously established effects of caffeine.

Positive Effects of Caffeine:

• Increases mental alertness.
• Enhances concentration.
• Improves mood.
• Reduces fatigue and delays its onset.
• Stimulates the release of catecholamines (hormonal mediators like adrenaline and dopamine).
• Mobilizes free fatty acids (promotes fat burning).
• Enhances the utilization of muscle triglycerides (energy sources for muscle activity during intense exercise or fatigue).
• Acts as a diuretic.
• Facilitates calcium metabolism and boosts the action of the sodium-potassium pump, supporting muscle membrane potential. This, in turn, can enhance muscle performance in sprinters and athletes engaged in strength training.

Research confirms that caffeine positively affects the nervous system (improving mood, learning ability, memory, attention, and performance) when consumed at doses of 1–5 mg per kg of body weight. For example, a cup of espresso contains an average of 100 mg of caffeine, while coffee brewed in a cezve or moka pot contains 90–200 mg.

The effect is more pronounced in people who do not regularly consume caffeine. According to a study by MJ Arnaud (2009), the positive effects of caffeine can be diminished when consumed with sugar. To maximize benefits, opt for tea or coffee without sugar.

When Caffeine Becomes Harmful

At doses of 9–13 mg per kg of body weight (6–9 cups of espresso for an average adult), negative effects start to appear: reduced total sleep time and poorer sleep quality.

At doses of 15 mg per kg of body weight, symptoms such as increased heart rate, headaches, nervousness, insomnia, irritability, or gastrointestinal disturbances may occur.

These symptoms are usually observed with chronic consumption of high doses or abrupt cessation of caffeine. The lethal dose of caffeine is more than 18 grams per day (approximately 2 liters of espresso).

Certain adverse effects, such as insomnia, nervousness, anxiety, or muscle tremors, may occur even at moderate doses, particularly in individuals sensitive to caffeine.

Caffeine Content in Beverages and Foods

• 90–200 mg — cup of espresso/americano
• 2–3 mg — cup of decaffeinated coffee
• 70–80 mg — cup of latte/cappuccino
• 40–100 mg — cup of instant coffee
• 100 mg — cup of cocoa
• 40–50 mg — cup of black tea
• 20–30 mg — cup of green tea
• On average, 80 mg — per 100 g of chocolate
• 65 mg — per 1 L of Coca-Cola
• 100–350 mg — per 1 L of energy drink

Additional Recommendations for Caffeine Consumption

• To ensure quality sleep, avoid caffeine 8–12 hours before bedtime.
• The ideal time for the last caffeine intake is before or after lunch.
• Approximately 25% of caffeine remains active after 12 hours, potentially disrupting deep sleep (slow-wave sleep) and REM phases, which are crucial for emotional performance the next day.
• Caffeine metabolism depends on genetic factors and liver enzyme activity (CYP1A2 gene). Individuals with a genotype associated with slower caffeine metabolism are at risk of side effects even at moderate doses.
• Opt for decaf if you experience adverse reactions (e.g., tremors or nervousness).
• Minimize consumption in cases of hormonal or medical conditions.