A review noted that those who drink the most coffee have up to a 29% lower risk of developing type 2 diabetes. Similarly, those who consume the most caffeine have up to a 30% lower risk ( 36).

You should read the nutrition label to be aware of the amount of caffeine per serving of coffee. Decaf coffee High caffeine intake has also been shown to raise blood pressure during exercise in healthy people, as well as in those with mildly elevated blood pressure ( 37, 38). In addition, there have been several reports of rhabdomyolysis related to excessive caffeine intake, although this is relatively rare ( 26, 27, 28, 29). Research has shown that while caffeine remains in your system for an average of five hours, the time period may range from one and a half hours to nine hours, depending on the individual ( 17). The American Academy of Pediatrics suggests that children under age 12 should not consume any food or beverages with caffeine. For adolescents 12 and older, caffeine intake should be limited to no more than 100 mg daily. This is the amount in two or three 12-ounce cans of cola soda. Caffeine and HealthZhang YP, Li WQ, Sun YL, Zhu RT, Wang WJ. Systematic review with meta‐analysis: coffee consumption and the risk of gallstone disease. Alimentary pharmacology & therapeutics. 2015 Sep;42(6):637-48.

Coffee. 1 cup or 8 ounces of brewed coffee contains about 95 mg caffeine. The same amount of instant coffee contains about 60 mg caffeine. Decaffeinated coffee contains about 4 mg of caffeine. Learn more about coffee. Ruxton CHS. The suitability of caffeinated drinks for children: a systematic review of randomised controlled trials, observational studies and expert panel guidelines. Journal of Human Nutrition and Dietetics. 2014;27(4):342-57.

References

Guest NS, VanDusseldorp TA, Nelson MT, et al. International society of sports nutrition position stand: caffeine and exercise performance. J Int Soc Sports Nutr. 2021;18(1):1. doi: 10.1186/s12970-020-00383-4 It’s important to note that coffee and tea contain other bioactive compounds (besides caffeine) that may also be beneficial. Summary

Kanani adds that those with certain heart conditions should reduce their caffeine intake, definitely keeping it below the 400 mg threshold.

Caffeine has stimulant effects and makes people more alert, reducing feelings of tiredness. It is widely believed to improve mental performance but the evidence for this is mixed. It has been suggested that the appearance of performance enhancement is because caffeine reverses withdrawal effects in regular users rather than improving overall mental ability. In people who are not regular users, any improvement is likely to be counteracted by anxiety and jitteriness which make it difficult to focus. Caffeine may in some circumstances increase a feeling of alertness whilst actually decreasing ability. Instead of F15, the shift key is used. This solves some of the issues with the above apps, but may cause the shift key to become "unpressed" sometimes