Collagen is the main protein of connective tissue in animals and the most abundant protein in mammals, making up about 25% to 35% of the whole-body protein content. It is naturally found exclusively in metazoa, including sponges. In muscle tissue it serves as a major component of endomysium. Collagen constitutes 1% to 2% of muscle tissue, and accounts for 6% of the weight of strong, tendinous muscles.The gelatin used in food and industry is derived from the partial hydrolysis of collagen.
Collagen is one of the long, fibrous structural proteins whose functions are quite different from those of globular proteins such as enzymes. Tough bundles of collagen called collagen fibers are a major component of the extracellular matrix that supports most tissues and gives cells structure from the outside, but collagen is also found inside certain cells. Collagen has great tensile strength, and is the main component of fascia, cartilage, ligaments, tendons, bone and skin. Along with soft keratin, it is responsible for skin strength and elasticity, and its degradation leads towrinkles that accompany aging. It strengthens blood vessels and plays a role intissue development. It is present in the cornea and lens of the eye in crystalline form. It is also used in cosmetic surgery andburns surgery. Hydrolyzed collagen can play an important role in weight management, as a protein, it can be advantageously used for its satiating power.
Collagen has been widely used in cosmetic surgery, as a healing aid for burn patients for reconstruction of bone and a wide variety of dental, orthopedic and surgical purposes. Some points of interest are:
- when used cosmetically, there is a chance of allergic reactions causing prolonged redness; however, this can be virtually eliminated by simple and inconspicuous patch testing prior to cosmetic use, and
- most medical collagen is derived from young beef cattle (bovine) from certified BSE (Bovine spongiform encephalopathy) free animals. Most manufacturers use donor animals from either "closed herds", or from countries which have never had a reported case of BSE such as Australia, Brazil and New Zealand.
- porcine (pig) tissue is also widely used for producing collagen sheet for a variety of surgical purposes.
- alternatives using the patient's own fat,hyaluronic acidor polyacrylamide gel are readily available.
Collagens are widely employed in the construction of artificial skin substitutes used in the management of severeburns. These collagens may possibly be derived from bovine, equine or porcine, and even human, sources and are frequently used in combination with silicones,glycosaminoglycans,fibroblasts,growth factorsand other substances.
Collagen is also sold commercially as a joint mobility supplement[ Because proteins are broken down into amino acids before absorption, there is no reason for orally ingested collagen to affect connective tissue in the body, except through the effect of individual amino acid supplementation.
Recently an alternative to animal-derived collagen has become available. Although expensive, this human collagen, derived from donor cadavers, placentas and aborted fetuses, may possibly minimize the possibility of immune reactions.
Although it cannot be absorbed through the skin, collagen is now being used as a main ingredient for some cosmetic makeup.