To understand the form and function of chitosan as a dietary supplement, it is important to define the substance from which it is derived, chitin. Chitin exists in nature as a polysaccharide and is a key structural component in forming the exoskeletons of crustaceans and insects. Chitosan is made via deacetylation from this organic substance. Shellfish are the main supplier in the manufacturing processes used to obtain supplemental chitosan. The shells are ground up into a fine powder where the deacetylation, or stripping of specified chemical compounds within the pulverized matter, takes place. Thereby forming N-deacetylated-chitin, or Chitosan.
Chitosan was universally accepted not as a nutritional supplement in many past cultures, but rather as a potent water detoxifier. It was used in the depletion and eradication of certain waterborne illnesses and toxic substances often found in municipal sources. Scientific advances in clinical research have proved that upon ingestion, chitosan is well tolerated and acts as a cellulose-like fiber within the human body. This finding proved influential for a myriad of health concerns including; a potent aid in the weight loss of adults, wound healing, and disease prevention.
These claims are, however, not yet substantiated within the majority of the medical community and requires more stringent and rigorous testing protocols.
Being a derivative of chitin, there are no direct sources of consumed chitosan in the diet other than supplemental chitosan. These products are offered in different synergistic formulas by a variety of nutritional supplementation companies. A food graph for chitosan has been omitted due to the lack of information concerning its direct food sources and the irregularities of consumption within the human diet.
Chitosan is bioadhesive in nature, and being positively charged, it can readily bind itself onto negatively charged surfaces. This characteristic not only enables chitosan to be formed into various fibers and films, but also enables it to chelate specific metal ions. As a dietary supplement, chitosan shows great promise towards advancements in various medical procedures and applications. Its greatest potential is seen in the transportation of polar drugs across epithelial tissue, and may even provide significant tissue healing capabilities. 
A less popular use for chitosan has been within the arenas of the abovementioned skin healing and tissue repair. Chitosan has been used in conjunction with common recovery treatments in skin graft patients and has demonstrated the capabilities of providing accelerating healing times.  Internal tissue injuries (ulcers) located within the digestive tract have also been treated with chitosan, primarily in concerns to the suppression of opportunistic bacterial infections.  Patients given three to six grams of supplemental chitosan over a two-week period showed a lowering in the risk of development of colon cancers.  This may be due in large part to the reduction of bacterial degeneration of the intestinal tract that is a result of direct disturbance/trauma.
Beyond chitosan’s application as a wound healer, therein lies a topic of considerable popularity with various chitosan supplements - weight loss. The past decade has witnessed an increased endorsement for chitosan to be marketed as a legit, revolutionary weight loss product. This usage for dietary chitosan, however, remains uncorroborated in many clinical studies.
Of particular interest, one such study set to determine the weight-loss effect on overweight subjects. 51 women were given either placebo or 2,400 milligrams of chitosan for a two-month duration. No weight reduction was noted in either the treated, or non-treated test groups. 
Despite these ongoing studies, supporters of dietary chitosan for weight loss may argue for chitosan as an effective weight loss tool. Chitosan advocates point to chitosan’s cellulose-fiber properties and its ability to inhibit the digestion and metabolization of fats and oils within the body. Scientists agree that although it harnesses the potential to reduce varying amounts of consumed fats and oils, the results may be minimal and further discouraging to an individual’s overall weight loss goals. 
Despite the controversial issue of chitosan’s affect on adult weight loss, this supplement may in fact significantly lower plasma cholesterol levels in the body and foods we consume. [7, 8] This finding is significant, as studies incessantly parallel the lowering of cholesterol with the reduction in the amount of bile and fatty acids consumed; both of which ultimately inhibit circulatory functioning throughout the body. Chitosan has also received praise for its continuance in the lowering of cholesterol without the negative effects often times associated with prescription cholesterol medications. 
Ongoing areas of clinical application for the benefits of chitosan supplementation include; non-insulin dependant diabetes mellitus and persons suffering from chronic renal failure. [10, 11] As with the majority of clinical trials concerning dietary supplements, definitive results of chitosan’s application in certain health conditions is often varied by chitosan preparations, different dosages, and times of administration.
Dosages for chitosan vary and are dependant upon individual need and the effects desired by dietary supplementation. It is recommended that individuals consume chitosan-containing supplements either directly before, or immediately following meals. Fat soluble vitamins, flavonoids, or prescription medications should also be avoided within a two-hour period following the ingestion of chitosan.
|Dosages for Condition:||Adults and Teenagers||Children up to age 12|
|Cholesterol lowering or (possible) fat absorption||1000-2000 milligrams twice per day, or before meals||Not Applicable|
Chitosan is not required by the body to fulfill physiological processes, therefore its consumption is not required and deficiencies of this nutrient in human biology do not exist. Long-term consumption of chitosan has not been thoroughly studied. Many scientists agree upon the elevated dangers of the development of a deficiency from vitamins A,D, E, and K. All of which are fat soluble vitamins and run the risk of being absorbed by chitosan.
Although mild, short term study of chitosan supplementation has resulted in adverse effects. Short-term studies have concluded that chitosan may produce changes in faecal metabolites, faecal microbiota and consumption.  More research is necessary to determine the severity of prolonged and excessive dosages of chitosan.
1. Kumar, MNV. A review of chitin and chitosan applications. Reactive and Functional Polymers 46, 1-27. (2000)
2. Azad AK, Sermsintham N, Chandrkrachang S, Stevens WF. Chitosan membrane as a wound-healing dressing: characterization and clinical application. J Biomed Mater Res. May 2004; 69B(2):216-22.
3. Bondarenko VM, Cherinets VM, Voroblev AA. Role of persisting opportunistic bacteria in the pathogenesis of the gastric and duodenum ulcer. Zh Mikrobiol Epidemiol Immunobiol. Jul 2003;(4):11-7.
4. Bone E, Tamm A, Hill M. The production of urinary phenols by guy bacteria and their possible role in the causation of large bowel cancer. Am J Clin Nutr. 1976;29:1448-54.
5. Pittler MH, Abbot NC, Harkness EF, Ernst E. Randomized, double-blind trial of chitosan for body weight reduction. Eur J Clin Nutr. 1999;53:379-381.
6. Egger G, Cameron-Smith D, Stanton R. The effectiveness of popular non-prescription weight loss supplements. Med J Aust. Dec 1999;171(11-12):604-8.
7. Gallaher, CM et al. Cholesterol reduction by glucomannan and chitosan is mediated by changes in cholesterol absorption and bile acid and fat excretion in rats. J Nutr 130, 2753-59. (2000)
8. Muzzarelli RA. Clinical and biochemical evaluation of chitosan for hypercholesterolemia and overweight control. EXS. 1999;87:293-304.
9. Jennings CD, Boleyn K, Bridges SR, et al. A comparison of the lipid-lowering and intestinal morphological effects of cholestyramine, chitosan, and oat gum in rats. Proc Soc Exp Biol Med. Oct 1988;189(1):13-20.
10. Tai, T-S et al. Effect of chitosan on plasma lipoprotein concentrations in Type 2 diabetic subjects with hypercholesterolemia. Diabetes Care 23, 1703-4. (2000)
11. Jing SB, Li L, Ji D, et al. Effect of chitosan on renal function in patients with chronic renal failure. J Pharm Pharmacol 1997;49:721-723.
12. Terada, A et al. Effect of dietary chitosan on faecal microbiota and faecal metabolites of humans. Microb Ecol Health Dis, 15-21. (1995)