The notion that the body can create proline and glycine is, of course, the reason that neither amino is considered “essential.” The ability to manufacture them easily and abundantly as needed, however, is probably true only of people enjoying radiant good health. Common sense suggests that the millions of Americans suffering from stiff joints, skin diseases and other collagen, connective tissue and cartilage disorders might be suffering serious shortfalls of proline, glycine and other needed nutrients.
… The remarkable resilience of cartilage comes from its gelatinous matrix. Far from being a jiggling blob of all-natural Jello, this matrix is highly structured with complex proteins and sugars. Best known are the proteoglycans that wind over, under and around the collagenous fiber network. As the name suggests, these giant molecules are comprised of proteins and sugars. Their primary job is to get and hold water, and they were designed to be very, very thirsty. Accordingly, their elaborate structure includes a central strand of hyaluronic acid on which hang as many as 100 of the biggest proteins found in the body. These in turn, divide into chain gangs known as chondroitin sulfates and keratin sulfates. In electrical terms, these chains carry negative charges and so repel each other. By keeping their distance from each other, they create space for the very water they attract.