The invention provides methods and compositions for preventing or treating (e.g., slowing the progression of, arresting, and/or reversing) tissue calcification in a subject in need thereof and, more particularly, the invention relates to methods of using menaquinone-7 (MK-7) and/or menaquinol-7 (MKH2-7) for preventing or treating (e.g., slowing the progression of, arresting, and/or reversing) tissue calcification in a subject with diabetes, chronic kidney disease, end stage renal failure, or a subject undergoing hemodialysis and/or receiving anticoagulant therapy. The invention further provides methods and compositions for reducing one or more symptoms of chronic obstructive pulmonary disorder (COPD), including using menaquinone-7 (MK-7) and/or menaquinol-7 (MKH2-7), for preventing or treating (e.g., slowing the progression of, arresting, and/or reversing) one or more symptoms of COPD.