This book is the first of two volumes that offer a comprehensive, up-to-date account of current knowledge regarding high-density lipoprotein (HDL), the changes that occur in HDL under different conditions, the clinical applications of HDL, and means of enhancing HDL functionality. HDL comprises a diverse group of lipoproteins and its composition and metabolism are dynamic. In this volume, the focus is on the changes observed in HDL under different health statuses, with particular attention to the functional and structural correlations of HDL and apolipoprotein A-1. The impacts of a wide variety of factors on HDL are examined in depth, covering, for example, diet, exercise, smoking, age, diverse diseases, and different forms of environmental pollution. It has long been known that HDL has anti-atherosclerotic and antidiabetic properties, and more recently its anti-aging activities have been recognized. These benefits of HDL are highly dependent on its lipids, proteins, apolipoproteins, and enzymes, and specifically their composition and ratios. In documenting the latest knowledge in this field, this volume will be of interest to both researchers and clinicians.