Nutritional Biochemistry of Non-Traditional Nutrients: Biochemical Roles of Lesser-Studied Phytochemicals, Rare Vitamins and Trace Minerals

Non traditional nutrients, including rare vitamins, trace minerals, and lesser studied phytochemicals, are increasingly recognized as important contributors to human biochemistry and health maintenance. Although they are often present in small amounts and have not received the same attention as classical nutrients, growing evidence shows that they participate in a wide range of physiological processes with implications for disease prevention and metabolic regulation. This review examines the classification, dietary sources, biochemical roles, and molecular mechanisms of these compounds, with emphasis on their relevance to energy metabolism, antioxidant defense, inflammation control, epigenetic regulation, and cellular signaling. Rare vitamins such as vitamin K2 illustrate the expanding biological significance of nutrients previously considered only in narrow physiological contexts, particularly through their roles in protein carboxylation, bone metabolism, and vascular protection. Trace minerals including selenium, molybdenum, vanadium, boron, and lithium contribute to essential enzymatic reactions, redox balance, hormone related regulation, and neurobiological function. In parallel, phytochemicals such as sulforaphane, betaines, polyamines, flavonoids, and microbial metabolites including urolithins demonstrate how plant derived and gut microbiota mediated compounds can influence detoxification pathways, mitochondrial function, inflammatory signaling, and gene expression. The review further shows that these nutrients act through coordinated biochemical mechanisms involving enzyme cofactors, transcription factors, nuclear receptors, methylation reactions, and signaling pathways such as Nrf2, NF kappa B, and GSK 3β. Their effects extend across key physiological domains, including oxidative stress modulation, immune regulation, mitochondrial efficiency, and maintenance of cellular homeostasis. Collectively, the evidence suggests that non traditional nutrients play meaningful roles that are not fully captured within conventional dietary frameworks. Despite these promising findings, important gaps remain in understanding their bioavailability, dose response relationships, long term safety, and clinical relevance. Further interdisciplinary research is needed to clarify their mechanisms of action and to establish evidence based strategies for their inclusion in nutrition science and public health practice. A deeper understanding of these bioactive compounds may support more refined nutritional interventions for the prevention and management of chronic disease.