Chitosan

Chitosan is an all-natural product, which is derived from the polysaccharide chitin. Chitin is found in the exo-skeletons of shrimp, crabs and other shellfish. Chitosan is a naturally occurring substance that is chemically similar to cellulose which is a plant fiber. Like plant fibers, Chitosan possesses many of the some properties as fiber, however unlike plant fiber, it has the ability to significantly bind fat, acting like a "fat sponge" in the digestive tract. Chitosan has the unique ability to attach itself to lipids or fats. There are no calories in Chitosan since it is not digestible. Chitosan attaches to fat in the stomach before it is metabolised. The Chitosan traps the fat and prevents its absorption in the digestive tract. The fat binds to the Chitosan fibre and becomes a large mass, which the body cannot absorb. This large mass is then eliminated from the body. Neutralising fat after it enters the stomach spares the body from having to deal with the fat. Chitosan fibre differs from other fibres in that it possesses a positive ionic charge. This positive charge gives Chitosan the ability to chemically bond with negatively charged lipids, fats and bile acids.

Chitosan can be referred to as a polycation. Since the early 1950s, polycations have been known to bind to red blood cells. Many studies since have shown that polycations are effective cellular agglutinating agents. In the early 1960s, chitosan was investigated for its agglutinating and binding abilities. It was found that chitosan, even at very low concentrations, had the ability to agglutinate red blood cells. This led to chitosan's consideration as a hemostatic agent. The agglutination of red blood cells by polycations is dependent both on polymer structure and molecular weight. Out of six common polycations, only chitosan was able to effectively initiate gel formation of heparinized blood. Chitosan with a molecular weight of 35,000 was only able to produce a loose coagulum in heparinized blood, while chitosan with molecular weights of 600,000 or above produced firm coagulum.

The mechanism of binding has also been researched. It is well known that the repulsive force between red blood cells is due to the high net negative charge on the cell membranes. This high negative surface charge is predominantly due to the presence of neurminic acid residues on the cell membrane. Researchers removed this acid by means of the enzyme neuraminidase. This process removed the high net negative charge of the red blood cell. The researchers then looked at the effect of chitosan on the modified blood cells. It was determined that chitosan did not cause any gelling of the blood cells. Therefore it was concluded that the gel formation of red blood cells is due to the interaction of the positively charged chitosan polymer with receptors containing neuraminic acid residues on the cell surface.

Chitosan provides a diverse spectrum of uses in the biological arena. In addition to the wound healing and burn treatment provided by chitosan, it has been shown to reduce serum cholesterol levels. To a certain degree, it has also been shown to stimulate the immune system. Chitosan, when coated on seeds, results in increased crop yields. Apparently, this is due to chitosan inducing a protective response in the germinating plant. Chitosan has been proven effective for many different applications. This is due in large part to its favorable biological and chemical properties. By understanding these properties, biomedical engineers will be able to fashion better tools to help the medical profession. Below are the useful biological and chemical properties of chitosan.

Chitosan can be used to inhibit fat digestion and as a drug delivery transport agent. It also has been used as a cholesterol lowering substance. Chitosan is marketed as a 'fat blocker'. It appears that it can impede fat absorption by 'gelling' with fat in the small intestine. Its side effect is that since it is made from sea food, some people have allergic responses to it. Also, you need a high concentration of Chitosan for it to 'gel' with fat.

Like dietary fiber, chitosan is not digestible but may have beneficial effects on the gastrointestinal tract. Chitosan appears to reduce the absorption of bile acids or cholesterol; either of these effects may cause a lowering of blood cholesterol. This effect has been repeatedly demonstrated in animals, and a preliminary human study showed that 3-6 grams per day of chitosan taken for 2 weeks resulted in a 6% drop in cholesterol and a 10% increase in HDL ("good") cholesterol. Another preliminary trial showed a 43% lowering of total cholesterol in people being treated for kidney failure with dialysis who took 4 grams per day of chitosan for 12 weeks. These people also appeared to have improved kidney function and less severe anemia after chitosan treatment.

Chitosan in large amounts, given with vitamin C, has been shown to reduce the absorption of dietary fat in animals fed a high-fat diet. However, the absorption of minerals and fat-soluble vitamins was also reduced by feeding animals large amounts of chitosan. No studies have been done on the effects of chitosan on dietary fat absorption in humans.

Chitosan and chitin are polysaccharide polymers containing more than 5,000 glucosamine and acetylglucosamine units, respectively, and their molecular weights are over one million Daltons. Chitin is found in fungi, arthropods and marine invertebrates. Commercially, chitin is derived from the exoskeletons of crustaceans (shrimp, crab and other shellfish). Chitosan is obtained from chitin by a deacetylation process.

Chitin, the polysaccharide polymer, is a cellulose-like polymer consisting mainly of unbranched chains of N-acetyl-D-glucosamine. Deacetylated chitin, or chitosan, is comprised of chains of D-glucosamine. When ingested, chitosan can be considered a dietary fiber.

Chemical Name: Poly-(1-4)-2-Amino-2-deoxy-?-D-Glucan
Molecular Formula: (C6H11O4N).n
Molecular Weight: 161. n
CAS NO.: 9012-76-4
Customs commodity code: 29329990.90

Chitosan related research information

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Chitosan supplementation and fecal fat excretion in men.
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The nutrient that binds fat.
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