Background/Objectives: Natural products derived from plants, animals, and microorganisms have long been used as nutritional supplements and are increasingly recognized for their potential role in preventing and managing human diseases. This narrative review aims to summarize current evidence on the therapeutic relevance of natural products as dietary supplements across major disease categories and to highlight their mechanisms of action, clinical efficacy, and safety considerations. Methods: A narrative literature review was conducted using peer-reviewed articles, systematic reviews, and clinical studies focusing on natural products used as nutritional supplements in disease management. Relevant data were analyzed thematically, with emphasis on bioactive compounds, mechanisms of action, and evidence from preclinical and clinical research. Results: Natural products, particularly plant-derived polyphenols, flavonoids, terpenoids, omega-3 fatty acids, and probiotic-derived metabolites, exhibit diverse biological activities, including antioxidant, anti-inflammatory, immunomodulatory, and antimicrobial effects. Evidence suggests potential benefits in cardiovascular diseases, metabolic disorders such as diabetes and obesity, neurodegenerative conditions, certain cancers, gastrointestinal disorders, and infectious diseases. However, clinical efficacy varies depending on compound type, dosage, and formulation. Key limitations include low bioavailability, variability in composition, and insufficient large-scale clinical trials. Safety concerns such as herb–drug interactions and lack of standardization remain significant challenges. Conclusions: Natural products as nutritional supplements represent a promising adjunct strategy in the prevention and management of various human diseases. While preclinical and early clinical evidence is encouraging, stronger clinical validation, improved standardization, and clearer regulatory frameworks are required to fully integrate these agents into evidence-based medical practice.
Dakanalis et al. (Sat,) studied this question.