This book collects 20 papers, focused on the fundamental role of magnesium in human health. It oers an overview of recent insights into magnesium from multiple perspectives. Magnesium is an essential mineral, which acts both as a signaling element and as a metabolite in cell physiology. The balance between intestinal absorption and renal excretion regulates its homeostasis. This book highlights the risks due to insucient uptake, frequently associated with the low content of magnesium in the modern western diet, suggesting strategies to reach the recommended dietary reference values. Actually, several diseases correlate with chronic low magnesium levels and have a high social impact, documented by several clinical trials reported in this book. In addition, innovative methods to detect physio-logical or pathological levels of magnesium in various body districts have been reported. For these reasons, this book could be useful in the eld of magnesium research, from cellular biology to clinical pathology.