Melatonin supplementation: new insights into health and disease

Melatonin supplementation has gained considerable attention for its potential health impacts. This study aimed to review the recent literature on melatonin supplementation and its implications in areas such as obesity, diabetes, gut microbiome, neurodegenerative diseases, cancer, sports performance, sleep quality, psychiatric disorders, pediatrics, pregnancy, and respiratory health. Additionally, assess the supplementation protocols, potential adverse effects, associated risks, and symptoms observed during supplementation.

An extensive search was conducted across multiple databases, including PubMed, Scielo, Web of Science, CrossRef, and Google Scholar, focusing on publications from 2011 to 2024. A total of 71 articles were collected and analyzed.

Recent studies highlight melatonin's promising antioxidant, anti-inflammatory, and immunomodulatory properties, particularly in improving sleep quality and addressing specific neurodegenerative diseases. Evidence supports its role in reducing anxiety in preoperative contexts and enhancing recovery under certain conditions in athletes. However, findings on melatonin's role in obesity, glycemic control, and gut microbiome regulation remain inconsistent and influenced by external factors such as diet and exercise. Similarly, evidence supporting its efficacy in cancer, psychiatric disorders, pregnancy, and pediatrics is limited and requires further research. For respiratory health, while melatonin's theoretical benefits include reducing oxidative stress and inflammation, current evidence is weak and largely preclinical. Concerns regarding adverse effects, including nightmares and grogginess, highlight the importance of thorough and careful monitoring. To ensure safety and effectiveness, supplementation protocols should be tailored to meet the unique needs of each individual.

Melatonin supplementation is not a universal solution but a potentially valuable tool in specific contexts. Its benefits are most evident in sleep regulation and certain neurodegenerative conditions. However, significant gaps in research, including inconsistent methodologies, small sample sizes, and limited data on long-term effects, necessitate further robust clinical trials. Individualized recommendations and cautious interpretation of findings are essential, particularly given the variability in outcomes based on study designs and populations.