Guarana is rich in caffeine, which can reduce fatigue and improve focus. Caffeine blocks the effects of adenosine, a compound that makes you feel drowsy and helps your brain relax.

Guarana is best known as an ingredient in popular energy drinks. It’s an excellent source of caffeine, which helps you maintain focus and mental energy. In fact, guarana seeds may contain four to six times more caffeine than coffee beans.

Caffeine works by blocking the effects of adenosine, a compound that helps your brain relax. It binds to adenosine receptors, preventing them from being activated.

A study found that people who took a guarana-containing vitamin supplement felt less fatigued while completing several tests, compared to those who took a placebo.

Interestingly, studies also show that guarana can reduce mental fatigue due to cancer treatment, without significant side effects.