The early decades of the twentieth century represented a pivotal period in the development of nutritional science, marked by groundbreaking discoveries that fundamentally changed our understanding of dietary requirements. This era witnessed the identification and characterization of vitamins—initially referred to as “accessory growth factors”—which were found to be essential for normal growth and physiological function beyond the known macronutrients and minerals. The foundation of vitamin research was established when Casimir Funk isolated an antiberiberi substance from rice polishings in 1912, coining the term “vitamine” to reflect its amine nature and vital importance. Shortly thereafter, the work of McCollum and Davis led to the discovery of fat-soluble factor A, distinguishing it from water-soluble nutrients and laying the groundwork for our modern classification system. These organic compounds, now collectively known as vitamins, serve as crucial regulatory molecules that must be obtained through dietary sources when endogenous synthesis is inadequate, as is the case for humans. The etymology of the word “vitamin” itself, derived from the Latin “vita,” meaning life, underscores their fundamental importance to biological systems. Historically, many vitamins were identified through the investigation of deficiency syndromes, with clinicians playing a key role in characterizing the pathological manifestations of inadequate intake. Contemporary understanding recognizes that vitamins encompass a diverse group of chemically unrelated compounds that participate in a wide array of biochemical processes. While originally conceptualized as single entities with specific functions, we now appreciate that vitamin activity often resides in multiple structurally related forms called vitamers. The conventional division into water-soluble and fat-soluble categories reflects important differences in their absorption, transport, storage, and excretion patterns. Water-soluble vitamins, including the B-complex group and vitamin C, are generally not stored in significant quantities and are readily excreted when circulating levels exceed renal thresholds. In contrast, fat-soluble vitamins (A, D, E, and K) associate with lipoproteins and cellular lipid components, resulting in more substantial body reserves but also greater potential for toxicity with excessive intake. Minerals, comprising ~4% of body weight, are indispensable for physiological function. They maintain electrochemical gradients, osmotic balance, and skeletal integrity while serving as enzymatic cofactors. Classified by physiological abundance, macrominerals (e.g., Ca2+, Mg2+) support structural and electrolyte roles, whereas microminerals (Fe2+, Zn2+, Cu2+) enable catalytic and regulatory functions. Modern research reveals their expanded roles in gene regulation, redox homeostasis, and cell signaling, establishing minerals as fundamental to health maintenance and disease prevention across biological systems. This chapter provides a comprehensive examination of micronutrients and their associated pathologies, integrating present knowledge about their biochemical mechanisms, physiological roles, and clinical significance. Particular emphasis is placed on their involvement in antioxidant defenses, inflammatory modulation, and their complex interplay with various disease states. The content is designed to serve as an authoritative reference for researchers, healthcare professionals, and advanced students seeking to understand the multifaceted roles of these essential nutrients in human health and disease. Recent advances in our understanding of vitamin functions, including newly identified roles in cellular signaling and gene regulation, are highlighted to provide contemporary perspectives on these classical nutritional factors.