Cholesterol-lowering Properties and Safety of Chitosan

Abstract

Chitosan (CAS 9012-76-4) is derived by alkaline deacetylation from chitin, an abundant polymeric product of natural biosynthesis especially in crustaceans. It is available in a primary, unorganised structure, but also in a microcrystalline form. As a dietary supplement, chitosan has been claimed to control obesity and to lower serum cholesterol. A variety of chitosan products have been freely available worldwide in health stores and pharmacies. This review summarises the current knowledge about cholesterol-lowering and safety properties of chitosan and focuses its possible application for the treatment of hypercholesterolaemia. Chitosan behaves as a polycationic(+) cellulose-like fibrillar biopolymer that forms films with negatively charged surfaces. It is not specifically hydrolysed by digestive enzymes in man, but limited digestion of chitosan due to bacterial flora and to the unspecific enzymes might occur. Negatively charged molecules in stomach attach strongly to the positive charged tertiary amino group (-NH3+) of chitosan. Therefore, chitosan reduces fat absorption from gastrointestinal tract by binding with anionic carboxyl groups of fatty and bile acids, and it interferes with emulsification of neutral lipids (i.e., cholesterol, other sterols) by binding them with hydrophobic bonds. In short-term animal studies the safety of chitosan has been good. There are only few studies with chitosan in humans. In man, dietary chitosan has been reported to reduce serum total cholesterol levels by 5.8-42.6% and low-density lipoprotein levels by 15.1-35.1%. In short-term trials up to 12 weeks, no clinically significant symptoms have been observed with chitosan compared to placebo. Mild and transitory nausea and constipation have been reported in 2.6-5.4% of subjects. Although chitosan has been clinically well tolerated, it cannot be recommended to people allergic to crustaceans.

Chitosan as a starting material for wound healing applications

“…Gades and Stern reported that quantities exceeding 4.5 g chitosan taken daily by human volunteers did not result in toxic effects (Gades & Stern, 2003). In addition, human trials up to twelve weeks showed no toxic effects, no allergies, and only nausea symptoms and constipation in 2.6 -5.4% of subjects (Ylitalo et al, 2002).…”

Effects of Emerita brasiliensis flour supplementation on normotensive (Wistar) and spontaneously hypertensive rats (SHR)

“…Since the shell of this animal contained significant amounts of chitin-chitosan biopolymer, it could be suggested that this reduction in blood pressure could reflect the ability of this compound to adsorb the lipids in the gut (Kanauchi et al 1994). Some studies have suggested there might be a reduction in blood pressure due to increased intake of chitosan, a positive high-density polymer that could attract and bind to the lipids (Ylitalo et al 2002;Gallaher et al 2002). In an acidic environment like the stomach, chitosan adsorbs fats during the digestion, facilitating their elimination through the feces.…”

Functions of Chitosan-Ferulic Acid Salt for Prevention of Hypertension

“…Actually, elevation of blood pressure in SHR was suppressed by the daily intake not only of FA, but also of CS-FA. On the other hand, CS-FA might change the CS-HCl salt in the stomach, allowing the salt to adsorb BA as well as CS-FA (Ylitalo, et al, 2002).…”