All about caffeine

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Caffeine is a natural compound found in a number of plant species including coffee, tea and cocoa4. A typical cup of coffee contains 75-100mg caffeine, whilst levels in brewed tea and cocoa are lower2,3,4. Caffeine is the principal active compound in coffee, but other compounds are also present which can make it difficult to differentiate effects of caffeine per se from other compounds4.

The European Food Safety Authority (EFSA) in a review on the Safety of Caffeine concluded that a moderate caffeine consumption, of around 400mg caffeine per day (the equivalent of up to 5 cups of coffee), can be enjoyed as part of a healthy balanced diet and an active lifestyle57. Pregnant and breastfeeding women are advised to limit their caffeine intake to 200mg per day57.

Research suggests that moderate caffeine consumption may be associated with a range of physiological effects, including mental and physical performance.

Caffeine is a mild central nervous stimulant, and is associated with increased alertness58. The European Food Safety Authority (EFSA) concluded that a cause and effect relationship has been established between a 75mg serving of caffeine and both increased attention and alertness22. Caffeine works as an adenosine receptor antagonist: with a similar structure to adenosine, caffeine may bind to the adenosine receptors, acting as an imposter and blocking the actions of adenosine, leading to feelings of alertness58. This effect may cause sleep disturbance in some59, but may also help in situations that require increased alertness, e.g. night shifts, long distance driving, and jet lag60-65.

Caffeine may also help to improve physical performance during endurance exercise. The European Food Safety Authority (EFSA) recognized that a cause and effect relationship has been established for caffeine intake and increased endurance performance and endurance capacity (in both cases for 3 mg/kg body weight 1 hour before exercise), and reduction in perceived exertion (4 mg/kg body weight 1 hour before exercise)23.

Research suggests that there is no involvement of the circuit of dependence in the physiological effects of caffeine, so caffeine does not fulfil the criteria to be described as a ‘drug of dependence’66-68.

It is important to note that the individual responses to caffeine ingestion may differ according to genetic variability and individuals often manage their own caffeine intake to suit their personal lifestyle5,6,14,15,16.

The content in ‘All about caffeine’ was last edited in June 2017. Papers in the Latest Research section and further resources are added regularly. 

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