It’s important to note that coffee and tea contain other bioactive compounds (besides caffeine) that may also be beneficial. Summary

In addition, caffeine consumed later in the day may interfere with sleep because its effects can take several hours to wear off. Liver protection. Coffee may reduce the risk of liver damage (cirrhosis) by as much as 84%. It may slow disease progression, improve treatment response, and lower the risk of premature death ( 37, 38).Caffeine in a dose dependent manner increases alertness in both fatigued and normal individuals. [56] Caffeine is a central nervous system stimulant that may reduce fatigue and drowsiness. [12] At normal doses, caffeine has variable effects on learning and memory, but it generally improves reaction time, wakefulness, concentration, and motor coordination. [52] [53] The amount of caffeine needed to produce these effects varies from person to person, depending on body size and degree of tolerance. [52] The desired effects arise approximately one hour after consumption, and the desired effects of a moderate dose usually subside after about three or four hours. [7] Caffeine improves muscular strength and power, [66] and may enhance muscular endurance. [67] Caffeine also enhances performance on anaerobic tests. [68] Caffeine consumption before constant load exercise is associated with reduced perceived exertion. While this effect is not present during exercise-to-exhaustion exercise, performance is significantly enhanced. This is congruent with caffeine reducing perceived exertion, because exercise-to-exhaustion should end at the same point of fatigue. [69] Caffeine also improves power output and reduces time to completion in aerobic time trials, [70] an effect positively (but not exclusively) associated with longer duration exercise. [71] Specific populations Adults

Coca-Cola Zero Sugar (Coke Zero) uses several common artificial sweeteners, including aspartame and acesulfame potassium (Ace-K). The remaining ingredients are carbonated water, caramel color, food additives, and natural flavors ( 1). Importantly, this is a large dosage of caffeine to consume within a short period of time, especially for someone who isn’t used to it or is highly sensitive to its effects. Dietary Guidelines for Americans. U.S. Department of Health and Human Services and U.S. Department of Agriculture. http://health.gov/dietaryguidelines/2015/guidelines. Accessed Feb. 1, 2020.Commercially prepared coffee- flavoured milk beverages are popular in Australia. [236] Examples include Oak's Ice Coffee and Farmers Union Iced Coffee. The amount of caffeine in these beverages can vary widely. Caffeine concentrations can differ significantly from the manufacturer's claims. [226] Birth control pills can extend the half-life of caffeine, requiring greater attention to caffeine consumption. [158] Medications