Nutrients frequently act in coordination with the absorption and metabolism of one nutrient often interdependent on the presence of others. For example, magnesium is essential for the activation of vitamin D, which, in turn regulates calcium and phosphate homeostasis, both of which are critical for cellular and organ function. A comprehensive understanding of disorders arising from disruptions in vitamin D and mineral ion metabolism is essential for explaining the pathophysiological mechanisms associated with their imbalance. The chapters of this book are selected to provide in-depth insights and highlight important areas of bidirectional relationship between vitamin D and mineral ions for future research to advance the understanding of the delicate interactions between nutrients and overall health.