Collagen is the most abundant protein in the human body (approximately 30% of the total protein content). It forms the structure of the tissues that make up the musculoskeletal system (cartilage, bones, tendons, ligaments, fascia…), protection and support tissues (skin and connective tissue) and tissues with specific functions (walls of blood and lymph vessels, cornea of the eye, scalp, gums, dentin…)
Its composition is unique due to its high content of the amino acids glycine and proline, and due to the hydroxylated forms of proline and lysine which are not found in any other protein. It has a fibrous structure, which offers great resistance and flexibility to the tissues it is part of.
Its macromolecule, with a molecular weight (MW) of approximately 300,000 Daltons (Da) is composed of three polypeptide chains of approximately 1,000 amino acids (AA) each, entwined to form a triple helix.
The helices are joined at each end forming long chains (tropocollagens). These chains are grouped in parallel to form micro fibrils, which are joined forming fibrils. These, in turn, create collagen fibres. These thick and flexible protein cords form the matrix
(three-dimensional network or bundles of fibres) which makes up the structure of collagenous tissues.
Around age 25, the cells begin to lose the ability to synthesise collagen, and its production falls by 1.5% each year. This process is accentuated around the age of 45, and when we get to our sixties, collagen production has fallen by more than 35%. Besides age, there are other factors that intensify the loss of collagen, such as overuse (sports and intense physical activity), trauma, menopause, obesity and cancer treatments.
Collagen makes up about 67% of the dry weight of cartilage. Its loss causes thinning and decreased consistency, triggering the arthritic process.
Collagen makes up about 80% of the dry weight of the tendons, ligaments and connective tissue associated to the muscles. Its loss favours the appearance of tendinitis, sprains, strains and muscle injuries.
Collagen makes up about 70% of the dry weight of the skin, concentrated in the dermis. Its loss causes the skin to become thinner and sagging, and wrinkles appear at the points subjected to greater flexion.
Collagen constitutes almost 30% of all organic matter existing in the bone and it is the support where the calcium salts are fixed. When the bone’s collagen matrix deteriorate , calcium salts detach (calcium deficiency) and it does not matter how much we supplement our diet with calcium and vitamin D, as the matrix cannot be remineralized if it is not regenerated beforehand.