Collagen is the most abundant protein in the human body and is the substance that holds the whole body together. It is found in the bones, muscles, skin and tendons, where it forms a scaffold to provide strength and structure.1,2
Endogenously produced collagen (i.e. collagen synthesised by the body) plays numerous important roles in health, with the breakdown and depletion of the body's natural collagen associated with a number of health problems. As such, exogenous (supplemental) collagen is increasingly used for medical and cosmetic purposes, including to help with healing and repair of the body's tissues.
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Fast facts on collagen
Here are some key points about collagen. More detail and supporting information is in the main article.25-27
- Protein makes up around 20% of the body's mass, and collagen makes up around 30% of the protein in the human body.
- There are at least 16 types of collagen, but 80-90% of the collagen in the body consists of types I, II, and III.
- Type I collagen fibrils are stronger than steel (gram for gram).
- Collagen is most commonly found within the body in the skin, bones and connective tissues.
- The word "collagen" is derived from the Greek "kolla," meaning glue.
- Collagen gives the skin its strength and structure, and also plays a role in the replacement of dead skin cells.
- Collagen production declines with age (as part of intrinsic aging), and is reduced by exposure to ultraviolet light and other environmental factors (extrinsic aging).
- Collagen in medical products can be derived from human, bovine, porcine and ovine sources.
- Collagen dressings attract new skin cells to wound sites.
- Cosmetic products such as revitalizing lotions that claim to increase collagen levels are unlikely to do so, as collagen molecules are too large to be absorbed through the skin.
- Collagen production can be stimulated through the use of laser therapy and the use of all-trans retinoic acid (a form of vitamin A).
- Controllable factors that damage the production of collagen include sunlight, smoking and high sugar consumption.
What is collagen?
Collagen is a hard, insoluble and fibrous protein that makes up one-third of the protein in the human body. 3 In the majority of collagens, the molecules are packed together to form very similar long thin fibrils.4
Collagen is the most common protein found in mammals.
According to MediLexicon, collagen comprises a family of genetically distinct molecules, all of which have a unique triple helix configuration of three polypeptide subunits known as alpha-chains.5
Each chain contains around 1,000 amino acids, and usually features an amino acid sequence consisting of glycine, proline and hydroxyproline.11
There are numerous different types of collagen, at least 16 types5, but 80-90% of collagens in the body belong to types I, II and III. The collagens in the human body are strong and flexible. Type I collagen fibrils are particularly tensile, and are stronger than steel, gram for gram.
Collagen and the body1-3,6-9
Collagen is most commonly found in the skin, bones and connective tissue within the body, providing structural support, strength and a degree of elasticity (in combination with elastin). In particular, collagens can be found in the extracellular matrix - an intricate network of macromolecules that determine the physical properties of body tissues.
In the middle layer of the skin - the dermis - collagen helps form a fibrous network, upon which new cells can grow. Collagen is also required in the replacement and restoration of dead skin cells. Some collagens also function as protective coverings for delicate organs in the body such as the kidneys.
Collagen production naturally declines with age, reducing the structural integrity of the skin and leading to sagging skin, the formation of lines and wrinkles and the weakening of cartilage in joints.
Collagen is secreted by a variety of different cells, but primarily by connective tissue cells. While young, the body consistently produces collagen, but collagen synthesis begins to decline around the age of 40, with a dramatic reduction in synthesis in women after menopause. By the age of 60 there is typically a considerable decline in collagen production.
On the next page we look at the medical uses of collagen, how collagen production can be increased and the factors that can deplete the levels of collagen found within the body.