Products
Chitosan is available in many countries in the form of tablets and capsules. It is not marketed as a drug, but as a medical device or food supplement. Chitosan is also used as a pharmaceutical excipient, for wound dressings and numerous other purposes. This article refers to its use against obesity.
Structure and properties
Chitosan is a β-1,4-polymer composed of linear, unbranched chains of D-glucosamine and -acetyl-D-glucosamine. It is therefore also referred to as polyglucosamine. The various products differ in dosage form, dosage, excipients used, molecular weight, degree of deacetylation, and fat-binding capacity. Chitosan is obtained by alkaline deacetylation from chitin, a polymer of -acetyl-D-glucosamine extracted from the shells of shrimps and crabs. It is therefore a modified natural product.
Effects
Chitosan binds lipids contained in food thus inhibits their absorption by excreting them in the stool. Chitosan is lipid-lowering, lowering LDL and increasing HDL. It is positively charged and binds the negatively charged fatty acids. It also swells with water, so it can be slightly satiating and shorten the intestinal transit time. How good the clinical effect of chitosan actually is in practice is controversial in the literature and opposing opinions can be found (e.g., Jull et al., 2008; Gades, Stern 2003). In addition, the yo-yo effect must also be considered in diets.
Areas of application
As a fat binder to support the treatment of obesity, for weight control, and as a lipid-lowering agent to reduce cholesterol and LDL.
Dosage
According to package insert. Since it is a dietary fiber, sufficient drinking should be done during the day (about 2 to 3 L). It is recommended to take chitosan only at two out of three main meals, so that the organism is sufficiently supplied with fat-soluble vitamins.
Contraindications
- Hypersensitivity
- Allergy to shellfish
- Underweight
- Children under 3 years
- Pregnancy and lactation
Caution is advised in growing children and adolescents, the elderly, chronic digestive problems (constipation, intestinal obstruction, after intestinal surgery, gastroparesis, intestinal polyps), inflammatory bowel disease, metabolic disorders or prolonged drug use. Refer to the package insert for complete precautions.
Interactions
Because chitosan binds lipids, it may potentially inhibit the absorption of fat-soluble drugs. These include, for example, oral contraceptives, hormones, retinoids, and steroids. A 4-hour time interval between ingestion and such drugs is recommended. Chitosan can also bind dietary components such as fat-soluble vitamins and essential fatty acids. These can be supplemented as needed.
Adverse effects
Possible adverse effects include digestive symptoms such as constipation, flatulence, lower abdominal pain, diarrhea, and bloating on the one hand, and allergic reactions such as skin rash, hives, and itching on the other. Chitosan exerts its effects locally in the intestine, is not digested and is not absorbed into the bloodstream.
