Caffeine is a xanthine alkaloid that has a psychoactive stimulant effect. It may be found in many plant species but the main source of caffeine is coffee or cocoa bean. It is a potent stimulant that causes the heart rate to increase, muscles to tighten up, and the pupils to dilate. It activates the adrenaline that gives a boost of energy. It also reduces the symptoms of asthma. It helps open up the airways for ease of breathing. It increases the metabolism and breaks down fats. It also helps increase muscle strength. It also prevents chronic fatigue syndrome. Caffeine helps ease headache. It also reduces the risk of diabetes, Parkinson’s disease, and colon cancer.