Effects of Caffeine and Coffee on Human Functioning
by Juan Del Coso Nutrients 2020, 12(1), 125;
As expected, 2019 has been a prolific year in terms of new evidence regarding the effects of coffee and caffeine consumption on diverse aspects of human functioning. A search in PubMed for published studies in 2019 on the effects of caffeine or coffee on humans, following the Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) guidelines [1], showed a total of 202 manuscripts that contained “coffee” (n = 65, which represents 32.2% of the total) or “caffeine” (n = 137, which represents 67.8% of the total) in the title of the manuscript (Figure 1). In the group of studies that investigated the effect of coffee intake, 58 (89.2%) were related to the use of this beverage to modify one or more health outcomes, five (7.7%) were related to the use of coffee to improve human performance and two (3.1%) assessed regular intake of coffee. In the group of studies that investigated the effect of caffeine intake (in most cases measured as the sum of all the sources containing caffeine such as coffee, tea, chocolate, energy drinks, etc.), 79 (57.7%) were associated with the use of caffeine with health variables, 52 (38.0%) were associated with the use of caffeine with ergogenic purposes, six (4.4%) were associated with regular caffeine intake. Briefly, this analysis shows the elevated amount of new information published each year regarding the utility of coffee and caffeine to produce a change in human functioning while reveals that most of the indications of coffee and caffeine are associated with producing a benefit on health or with enhancing human performance.
Interestingly, 75.2% of the study sample perceived coffee as negative for their health, while the investigation determined that coffee users that seek potential health benefits of coffee are more likely to be male, young, and working. The other investigation associated with coffee intake was a systematic review and meta-analysis of prospective studies on the effect of this beverage on the risk of colorectal cancer [3]. In this study, a total of 26 investigations were analyzed while the main finding was a weak but significant protective effect of habitual coffee intake on the risk of suffering colon cancer.
In addition, the regular intake of decaffeinated coffee exerted a protective effect against colorectal cancer, suggesting that part of the positive effect of coffee to reduce the risk of suffering colorectal cancer is independent of caffeine.
In the investigations that studied caffeine’s ergogenicity, several shared a common message because they reflect that the acute intake of caffeine (from ~1 to ~6 mg/kg of body mass) was effective to improve different aspects of physical and sport performance
