Free radicals

Molecules or atoms that are toxic to the human body; usually oxygen or an oxygen-based compound that have lost electrons and are not stable.
The fatty membrane that surrounds cells is the prime target for free radical attack. The type of free radical formed when cellular membrane is damaged is called lipid peroxides. The damaged cellular membrane is no longer able to transport nutrients, oxygen and water into the cells or regulate the removal of waste products. Free radicals can also attack nucleic acids that comprise the genetic code within each cell.
Collagen is particularly susceptible to free radical damage. When this damage occurs, collagen molecules break down and then link back up again in a different formation; this process is referred to as cross-linking or glycation. Cross-linking causes normally mobile collagen to become stiff, less elastic and a tendency to become brittle and fragile. This therefore restricts cell nourishment and waste elimination, which lowers the vitality of cells and ultimately, the vitality of the body.