Corvalen? D-ribose, distributed exclusively to healthcare professionals by Douglas Laboratories, is a natural pentose sugar that is designed for the support of cardiovascular health, fatigue, energy production, and mitochondrial function? This slightly sweet d-ribose powder is rapidly dissolved and readily absorbed into the body. Corvalen? is an all-natural D-ribose clinically proven to help restore energy, support cardiac function and reduce muscle stiffness, soreness, and fatigue.