From the Guidelines
A safe amount of daily caffeine consumption for most healthy adults is up to 400 milligrams (mg), as supported by the most recent evidence from the 2020 study published in Advances in Nutrition 1. This is roughly equivalent to three to five 8-oz (237 mL) servings of coffee per day. However, individual tolerance varies based on factors like body weight, medications, and health conditions.
- For pregnant women, the recommended limit is 200 mg daily, as advised by the European Food Safety Authority 1.
- For adolescents, consumption should not exceed 2.5 mg · kg body weight–1 · d–1, which is equivalent to 1 or 2 cups of tea or 1 small cup of coffee daily, according to the systematic review of RCTs, observational studies, and expert panel guidelines 1.
- Children should generally avoid caffeine, as concern has been raised that caffeine may cause behavioral issues in this age group 1. It's best to spread consumption throughout the day rather than consuming large amounts at once.
- Caffeine works by stimulating the central and sympathetic nervous system, providing a feeling of alertness after consumption 1. Side effects of excessive consumption can include insomnia, jitters, increased heart rate, headaches, and anxiety.
- If you're sensitive to caffeine or have certain health conditions like heart problems, anxiety disorders, or high blood pressure, you may need to consume less or avoid it altogether, as the evidence generally supports that consumption of ≤400 mg caffeine/d in healthy adults is not associated with adverse cardiovascular effects, behavioral effects, reproductive and developmental effects, acute effects, or bone status 1. Pay attention to hidden sources of caffeine in medications, chocolate, and some flavored foods.
From the Research
Daily Caffeine Consumption
The safe amount of daily caffeine consumption is a topic of interest in various studies.
- According to 2, the daily caffeine intake should not exceed 400 mg, and recommendations on drinking coffee should consider the "strength" of various types of coffee to avoid regular intake of high amounts of caffeine.
- A study published in 3 suggests that consuming up to 400 mg/day (1-4 cups per day) of caffeine is safe, but it is essential to consider the time gap between coffee consumption and some drugs to avoid interaction.
- Another study 4 states that moderate intake of caffeine can help prevent and modulate several diseases, but long-term or excessive caffeine consumption can lead to addiction, insomnia, migraine, and other side effects.
Caffeine Intake Guidelines
- The studies 2, 3, 4 emphasize the importance of considering individual sensitivity to caffeine and physical condition when determining a safe amount of daily caffeine consumption.
- Children, adolescents, pregnant women, and people sensitive to caffeine should restrict or reduce their intake to avoid potential adverse effects 4.
- Caffeine can be a powerful ergogenic aid at levels that are considerably lower than the acceptable limit of the International Olympic Committee, and it may be beneficial in training and competition 5.
Caffeine Effects
- Caffeine may contribute to the prevention of inflammatory and oxidative stress-related diseases, such as obesity, metabolic syndrome, and type 2 diabetes 3.
- Caffeine consumption seems to be associated with a lower incidence of several types of cancer and a reduction in the risk of all-cause mortality 3.
- The mechanism by which caffeine elicits its ergogenic effects is unknown, but it may work by creating a more favorable intracellular ionic environment in active muscle 5.