CAS No.: 9012-76-4
HS Code: 29329990.90
Chemical Name: Poly-(1-4)-2-Amino-2-deoxy-?-D-Glucan
Molecular Formula: (C 6 H 11 O 4 N)¡¤ n
Molecular Weight: 161¡¤n
Chitosan is natural high-molecular polysaccharide extracted from the sea shrimp and crab shell, as food additive and raw material for pharmacy. It is white powder, non-harmful, odourless, non-pollutive, non-corrosive, non-burnable, non-explosive, according with the export standard of WTO.
What Is It?
The shells of crabs, lobsters, and other crustaceans contain a nondigestible fiber called chitosan. Extracted and taken in supplement form with meals, chitosan reportedly encourages weight loss by binding to fat molecules in the digestive tract, preventing the body from absorbing the fat.
Whether chitosan is safe and effective as a diet aid remains controversial, however. Some small studies have found that taking the supplement may result in weight loss. In one trial, people who used chitosan for a month in conjunction with a calorie-controlled diet lost, on average, 8% of their body weight. This translates into 16 pounds for a 200-pound person. How much this was due to the chitosan and how much to the calorie restriction is unknown.
Other studies, however, have not reported such positive findings. A carefully designed 1999 trial in England involving 34 overweight individuals, for instance, found that chitosan supplements were no better than a placebo in reducing body weight.
Some advertisements encourage taking chitosan so that you can "indulge" in a fatty meal. This is definitely not the case. While chitosan does work to bind to some of the fats in your digestive tract, it certainly doesn't cover them all. The bottom line is that anyone wishing to try chitosan for weight loss will have to watch their total calorie intake, reduce the fat in their diet, and exercise.
Researchers are still examining whether chitosan may lower cholesterol (another effect of its fat-binding qualities) or even have a role to play in controlling ulcers, high blood pressure, and arthritis.
- Although chitosan is quite safe, it's possible that, in theory at least, it could block the absorption of the fat-soluble vitamins (vitamins A, D, E and K) as well as the essential fatty acids (the "good" fats, like omega-3 and omega-6). So be sure to take a vitamin supplement at least an hour or so before the chitosan.
- Don't take chitosan if you have an allergy to shellfish.
- Chitosan doesn't get absorbed into the bloodstream, which means it's largely free of the side effects that so many people experience with numerous prescription (and nonprescription) weight-loss medications and supplements.
- Because no extensive safety studies have been done, women who are pregnant or breast-feeding and children under age 14 should avoid chitosan.
Where did chitosan come from?
Regardless of chitosan's miraculous overview, it is a very simple substance which has been around for ages. It is taken from chitin, a polysaccharide found in the exoskeletons of crustaceans. It is processed by removing the shells from shellfish such as shrimp, lobster, and crabs. The shells are then ground into a pulverous powder. This powder is then deacetylated, or basically stripped of specific chemical groups which allows the compound to thus actively "soak up fats." Or so this is what the producers claim. It has been used in the past in the process of detoxifying water. It was simply spread over the surface of water, where it would immediately absorb any toxic substances such as greases, oils, or dangerous heavy metals. The process is so complete that a scum forms over the surface of water and is then easily removed. For this reason, chitosan is extremely popular all over the world in water purification plants. The present form of chitosan has just been introduced recently as a weight loss supplement.
How chitosn is used for weight loss?
Let's now take a look at exactly what is chitosan and how it is used for weight loss. The allegations of how chitosan works are as follows. However, note that there is no significant studies to thus back up this information or to explain exactly how such procedures take place. Basically stated, chitosan is a special fiber which is able to "soak up" or absorb anywhere from six to ten times its weight in fat and oils. In substance, it is chemically similar to the plant fiber, cellulose. However, chitosan is able to significantly bind with fat molecules and convert them into a form which the human body does not absorb. (Revolutionary Discovery: Chitosan) It claims to affect the fat prior to it reaching the stomach and thus the fat never has a chance to be metabolized. It prevents the absorption and storage of fat by converting into a gel which "traps" the fat. In some sort, it creates a "grease ball" from this excess fat, which is too large to be absorbed by the body. It thus becomes an inert substance and is excreted in the stool. (Absorption of Fats) Chitosan fiber is unlike other fibers in that it carries a positive ionic charge. Since lipids, fats, and bile acids all possess negative charges, there is a chemical bond between the two and thus they attract naturally to one another. (Fat Magnet) This unique ability is what makes chitosan so remarkable. This amazingly "too good to be true" ability is also what causes suspicions to arise on the validity of these claims.
Specific Research Studies:
Specific studies which tested the effects of chitosan as a weight loss supplement on humans were near to impossible to find. One study which apparently tested the effects of chitosan to the hypocholesterolaemic response of human subjects was published in 1993 by a group of Japanese doctors. However, any copy of this report was not available and only references from this report were made. The only other true scientific study that was done was on the effects on broiler chickens to chitosans of different viscosity. In this prospective cohort study setup, broiler chickens were fed ad libitum on a control diet based on maize and maize starch diets containing low-, medium-, or high-viscosity chitosans at a level of 15 g/kg. The diets began of the total 224 broiler chickens on the second day of their lives. The groups were randomly allocated and divided into separate cages of mixed sex. The cages contained raised wire floors in a windowless, light- and temperature-controlled room. The birds all had free access to water and feed for the duration of the experiment. Both were monitored specifically to observe if either was consumed more or less with the addition of chitosan to the diet. After the 22 day experiment, many conclusions were drawn. The 22 days consisted of regular check-ups including body weight testing, blood plasma tests, and feed intake records. Feeding the high-viscosity-chitosan-containing diets reduced ileal fat digestibility by 8% on average. However, increasing the viscosity of the chitosan fraction could not be correlated specifically with the increases in terminal ileal digesta viscosity. Therefore, it could not be established that any necessary increases in chitosan are necessary to receive the few benefits accredited directly to the fiber itself. Significant reductions in body weight, feed intake and plasma control concentrations were observed. (Razdan & Pettersson, 1994)
Discussion on Chitosan from Researchers:
With the unavailability of specific research studies to support the claims made on chitosan as a revolutionary weight loss supplements, one must be careful on what is fact and what is speculation. The following are conclusions and specific discussion made from researchers, although take note that their specific studies were not given with precise accounts of their experimentation. It is now generally accepted that soluble dietary fibers increase gastrointestinal lumen viscosity (Edwards, 1990) and delay gastric emptying (Chang, 1983). Chitosans have specifically been shown to alter bile acid composition, increase neutral sterol excretion and reduce ileal fat digestibility (Fukada, 1991; Maezaki, 1993; Razdan & Pettersson, 1994). The mechanisms by which chitosans achieve these effects are not fully established, although increased intestinal viscosity and increased bile acid-binding capacity are two proposals currently favored (Furda, 1990). Since polyglucosamines are the second-most-ubiquitous dietary fiber after cellulose, it is reasonable to assume that much more research regarding the nutritional significance of these important dietary fibers is to be expected (Knorr, 1991). Chitosan has such characteristics that are associated with a dietary fiber which are assumed to be related to the reductions in cholesterol as well as increases in the excretion of neutral steroids observed in animal experiments (Furda, 1990; Ikeda, 1993; Razdan & Pettersson, 1994). Chitosan, which is largely deacetylated, contains cationic groups located on the polyglucosamine chain (Sugano, 1993). Thus, chitosan may have a bile acid-binding capacity, causing entrapment or disintegration of mixed micelles in the duodenum and ileum (Furda, 1990). This interruption in bile acid circulation would lead to reduced lipid absorption and increased sterol excretion. Chitosan is relatively insoluble in water but is soluble in dilute acids, giving rise to highly-viscous dietary fibers (Furda, 1990). It has been suggested that viscous dietary fibers such as chitosan inhibit uptake of dietary lipids by increasing the thickness of the intestinal lumen boundary layer, a proposal again supported by numerous animal experiments (Sugano, 1993; Ikeda, 1993).