Analysis of a mutant mouse exhibiting accelerated aging identified phosphorus as a pro-aging factor in mammals. In the blood, phosphorus exists in the form of phosphate ions and colloidal particles composed of solid-phase calcium-phosphate and serum protein fetuin-A, which are termed calciprotein particles(CPP). Blood CPP levels increase with age and decline of renal function. Because CPP have the ability to induce inflammation and vascular smooth muscle cell calcification in vitro, we hypothesize that CPP may serve as a pathogen that accelerates aging. Therapeutic interventions in phosphate and/or CPP may open a new avenue for practical anti-aging medicine.