Does caffeine work?

What is Caffeine?

Caffeine is a substance found naturally in many plants. It’s also abundant in coffee, tea, soda, and chocolate, and is taken in powders, pills, or an ingredient in energy supplements. Adenosine slows down nerve cell activity and causes drowsiness. Caffeine binds to the same receptors as adenosine, blocking its effects. This causes increased neuron firing. The pituitary gland registers this activity as an emergency. This releases hormones causing increased breathing, heart rate, blood flow to muscles, and blood pressure. It also decreases blood flow to the stomach and releases sugar into the blood for extra energy. Read More


Overall Effectiveness Rating for Caffeine

The overall effectiveness rating for caffeine is 2 out of 3. This rating means there is some evidence that using caffeine may lead to positive results. This rating also means that some evidence does not back up all claims. Below you can find individual ratings for specific claims.

Overall Confidence Rating for Caffeine

There are 60 studies in the database on caffeine; the confidence rating is 140. A score above 80 means the effectiveness rating for this supplement is reliable. A score under 80 means there is insufficient evidence to ensure a reliable effectiveness rating. Note, this rating is for caffeine as a whole. There are also individual ratings for the claims below.

Products Containing Caffeine

There are 182 products in the database containing Caffeine. Follow the link to see the full list.

Individual Claims

The overall ratings above do no necessarily reflect each claim about caffeine. Individual claims can have higher or lower ratings. For example, some supplements may have a lot of backing for one claim, but be completely useless for another. Click on claims below for more information.

Performance Claims Effectiveness Rating Confidence Rating
improve agility
improve cardiovascular endurance
improve cycling performance
improve muscular endurance
improve running performance
improve sports performance
improve sprint performance
decrease fatigue
increase strength
improve cycling sprint performance
increase alertness

Mental Health Claims Effectiveness Rating Confidence Rating
improve cognitive ability
improve memory
improve mood

General Health Claims Effectiveness Rating Confidence Rating
improve insulin sensitivity