Chondroitin sulphate is a molecule made of sugars and amino acids. It exists within the category of metabolically active molecules known as glycosaminoglycans (GAGs). At one time these substances were commonly referred to as mucopolysaccharides. Glycosaminoglycans comprise the ground substance or “filler” in the extracellular matrix of collagen. In humans GAGs can be found in cartilage, bone, cornea, skin and the walls of large arteries. 
There are four different structural varieties (isomers) of chondroitin sulphate, and each is dependent upon the arrangement of the sugars and amino acids. They are labeled A, B, C, and D; with chondroitin sulphate A being the most abundant in human biology. Most supplements contain a mixture of A and C, which are the most abundant forms found in shark and whale cartilage products. However, small amounts can also be found naturally in humans. The different isomers have different molecular weights, and those with lower weights are more readily absorbed and integrated into tissues.
Chondroitin sulphate is absorbed in the stomach and small intestine. Once absorbed, chondroitin sulphate has been shown to enter the joint space, with a tropism, or affinity for the knee joint.  However some of the chondroitin sulphate is digested and broken down to glucosamine, which is also a (GAG) and serves the same purpose.
Chondroitin sulphate’s main function is to maintain structural integrity and function of cartilage. It can also be used to relieve pain in musculoskeletal disorders such as osteoarthritis (OA). It has also shown some mild anti-inflammatory activity. Although the exact mechanism of action is not completely understood, studies have determined that supplemental chondroitin sulphate does, in fact, enter the joint spaces (cavities).
Chondroitin sulphate is derived from animal sources. Most chondroitin sulphate sold as a supplements are derived from either shark, whale, bovine (cow), or pork sources. There are no vegetable sources of chondroitin sulphate.
Chondroitin sulphate is best used as a protective element for cartilage. Considered a chondroprotective agent, it provides shock relief for joints by allowing cartilage to “sponge” up more water. It also increases the hyaluronic acid in the synovial fluid. This also allows for a greater volume of fluid in joint spaces, thereby enhancing the ‘smooth’ functioning of the joint. 
Chondroitin sulphate has been well studied as an alternative treatment for osteoarthritis (OA). It has been shown to decrease the symptoms of OA, including pain, swelling, decreased mobility, and joint crepitus (cracking).  By stimulating hyaluronic acid, symptoms of OA are further improved. Because chondroitin sulphate has the potential to improve the synovial fluid of a joint, it may also be an effective adjunct treatment for rheumatoid arthritis, which begins with synovial fluid abnormalities. 
Chondroitin sulphate has also been shown to be effective for some symptoms of erosive osteoarthritis.  One case study showed chondroitin sulphate’s effectiveness at treating vertebral disc degeneration, which was followed up with positive changes on MRI. 
The most common dosage used for osteoarthritis is 1200 milligrams per day. It can be taken in divided doses (400 mg three times per day) or in one large dose with the same therapeutic effect.  This dose can also be used for other conditions, in which chondroitin sulphate may also provide some therapeutic benefit for.
The overall bioavailability of chondroitin sulphate is approximately 12%. Studies show it is better absorbed when taken mixed with water, versus being taken in capsule form. 
Side effects from high intakes of chondroitin sulphate are minimal. They may include GI distress, with noticeable nausea and diarrhea. Although chondroitin sulphate contains sulfur, there have been no reported allergic reactions in individuals who are allergic to sulfur-containing, or sulfa, drugs. 
The use of chondroitin sulphate in women who are pregnant or nursing, and children is contraindicated due to the lack of information on the effects of supplementation in these populations and the potential for interaction with growth.
Individuals who have a bleeding disorder, including hemophilia and peptic ulcer disease, as well as those taking anti-coagulants or anti-platelet medications, should use caution when taking chondroitin sulphate due to the potential risk of increased bleeding. It is important to notify your physician if you are taking chondroitin sulphate , or plan to begin taking it, if you are at an increased risk for bleeding or hemorrhage.
Individuals who are on a salt-restricted diet should take the salt free form of chondroitin sulphate.
There is no known toxicity from over dosage and no drug interactions associated with the intake of chondroitin sulphate.
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