|This article relies too much on references to primary sources. (December 2013)|
||This article possibly contains original research. (December 2013)|
Hydrolyzed collagen is produced from collagen found in the bones, skin, and connective tissue of animals such as cattle, fish, horses, pigs, and rabbits. The process of hydrolysis involves breaking down the molecular bonds between individual collagen strands using combinations of heat, acids, alkalis, or enzymes. Typically, with skin-sourced collagen, hides are put in a lime slurry pit for up to 3 months, loosening collagen bonds; the hides are then washed to remove lime, and the collagen extracted in boiling water. The extracted collagen is evaporator concentrated, desiccated with drum driers, and pulverized.[unreliable source?]
Amino acid content
The amino acid content of hydrolyzed collagen is the same as collagen. Hydrolyzed collagen contains 20 amino acids, predominantly glycine, proline and hydroxyproline, which together represent around 50% of the total amino acid content.
|Other essential amino acids||16%|
|Other non-essential amino acids||12%|
Amino acid content
Hydrolyzed collagen contains 8 out of 9 essential amino-acids, including glycine and arginine—two amino-acid precursors necessary for the biosynthesis of creatine. It contains no tryptophan and is deficient in isoleucine, threonine, and methionine.
The bioavailability of hydrolyzed collagen in mice was demonstrated in a 1999 study; orally administered 14C hydrolyzed collagen was digested and more than 90% absorbed within 6 hours, with measurable accumulation in cartilage and skin. A 2005 study in humans found hydrolyzed collagen absorbed as small peptides in the blood.
Effects on skin
Ingestion of hydrolyzed collagen may affect the skin by increasing the density of collagen fibrils and fibroblasts, thereby stimulating collagen production. It has been suggested, based on mouse and in vitro studies, that hydrolyzed collagen peptides have chemotactic properties on fibroblasts or an influence on growth of fibroblasts.
Joint and bone effects
Some clinical studies report that the oral ingestion of hydrolyzed collagen decreases joint pain, those with the most severe symptoms showing the most benefit. Beneficial action is likely due to hydrolyzed collagen accumulation in the cartilage  and stimulated production of collagen by the chondrocytes, the cells of cartilage. Several studies have shown that a daily intake of hydrolyzed collagen increases bone mass density. It seems that hydrolyzed collagen peptides stimulated differentiation and osteoblasts activity- the cells that build bone- over that of osteoclasts (cells that destroy bone).
However, other clinical trials have yielded mixed results. In 2011, the European Food Safety Authority Panel on Dietetic Products, Nutrition and Allergies concluded that "a cause and effect relationship has not been established between the consumption of collagen hydrolysate and maintenance of joints". Four other studies reported benefit with no side effects; however, the studies were not extensive, and all recommended further controlled study. One study found that oral collagen only improved symptoms in a minority of patients and reported nausea as a side effect. Another study reported no improvement in disease activity in patients with rheumatoid arthritis. Another study found that collagen treatment may actually cause an exacerbation of rheumatoid arthritis symptoms.  
Hydrolyzed collagen, like gelatin, is made from animal by-products, including skin, bones, and connective tissue. It is possible that consumption of hydrolyzed collagen risks contraction of Transmissible spongiform encephalopathy.
The U.S. Food and Drug Administration (FDA), with support from the TSE (Transmissible spongiform encephalopathy) Advisory Committee, has since 1997 been monitoring the potential risk of transmitting animal diseases, especially bovine spongiform encephalopathy (BSE). The FDA study concluded: "...steps such as heat, alkaline treatment, and filtration could be effective in reducing the level of contaminating TSE agents; however, scientific evidence is insufficient at this time to demonstrate that these treatments would effectively remove the BSE infectious agent if present in the source material."
In cosmetics, hydrolyzed collagen may be found in topical creams, acting as a product texture conditioner, and moisturizer.
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- Helps to reduce joint pain associated with osteoarthritis (Bruyère et al. 2012; Benito-Ruiz et al. 2009; Clark et al. 2008).
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