Mesoglycan is a substance found in the body, especially in the heart and blood vessels (veins and arteries). Vascular glycosaminoglycans (or GAGs, sometimes called mucopolysaccharides) are the building blocks of blood vessel walls. Other examples of GAGs include chondroitin and hyaluronic acid. Supplemental mesoglycan has been shown in scientific and clinical studies to support strong, flexible veins and arteries, healthy blood circulation, heart and brain health, and more.