Vitamins are essential micronutrients that the body cannot make in sufficient quantity on its own, and each has its own biochemical roles and deficiency diseases. This course covers vitamin A and its role in vision and retinoic acid signaling, vitamin D's role in calcium homeostasis – including how parathyroid hormone and calcitonin regulate calcium and phosphate levels and how vitamin D acts inside the cell – and vitamin B12 and folate metabolism, including how folate metabolism connects to the nucleotide synthesis pathways covered in Purine and Pyrimidine Metabolism. Throughout, the course ties each vitamin's biochemistry to the clinical conditions that arise from deficiency or dysregulation, giving you a working knowledge of vitamins that applies directly to nutrition and clinical coursework.