How does cross-linking of collagen affect the elasticity of skin, tendons, and blood vessels?

As we age, the collagen within our skin, tendons, and blood vessels undergoes a process of increased cross-linkage between and within its molecular fibers.12

Contrary to the idea that these tissues simply lose elasticity due to the collagen itself, this chemical process leads to increased crystallinity and rigidity in the structural proteins. As these cross-links accumulate, the tissues become stiffer and less flexible, which contributes to a general sense of body stiffness. In the case of blood vessels, the loss of elasticity is also significantly influenced by the fragmentation of elastin, a separate protein responsible for vessel wall flexibility.2

Ultimately, this cross-linking process reduces the permeability of these tissues, hindering the transport of essential nutrients, hormones, and antibodies to cells. This structural change is often compared to the tanning process that converts animal hides into leather, illustrating how the formation of these bonds fundamentally alters the physical properties of the tissue.23