The effect of caffeine on human quality of life: Myths and realities

Introduction: caffeine is the most widely consumed psychoactive agent globally. Historically surrounded by controversies, current scientific evidence reveals a complex coexistence of potential benefits and risks dependent on dosage and individual characteristics. Objective: to analyze the impact of caffeine consumption on people's quality of life, critically examining myths and realities in light of the most recent scientific evidence. Methods: a descriptive and narrative literature review was conducted through standardized searches in academic databases (PubMed, Scopus, SciELO) for publications between 2020 and 2026, selecting and qualitatively analyzing clinical and epidemiological evidence. Development: caffeine metabolism varies based on polymorphisms of the CYP1A2 gene. Moderate consumption (3 to 5 cups daily) disproves the myth of arrhythmogenic risk and is inversely associated with the risk of type 2 diabetes, dementia, liver diseases (steatosis and cirrhosis), and hepatocellular carcinoma, while also serving as an ergogenic aid in sports. However, high intake increases the risk of acute myocardial infarction and causes adverse effects such as insomnia, anxiety, and dependence. In pregnant women, intake is dose-dependently associated with a higher risk of small-for-gestational-age newborns. Furthermore, energy drinks represent a distinct cardiovascular and behavioral risk for children and adolescents. Conclusions: moderate caffeine consumption can be part of a healthy lifestyle in adults. However, recommendations must be individualized based on genetic, physiological, and safety factors, especially in vulnerable populations.