Chitosan is one of the most commonly cited polymers in the scientiﬁc research. It has several biomedical and biopharmaceutical applications and is also used in food science and technology. It possesses characteristics like non-toxicity, biocompatibility, biodegradability and adsorption properties, making it a great functional material. Nowadays, chitosan is produced commercially all over the world and some of the well-known producers are USA, Norway, Australia, India, Japan and Poland. (1)
What is Chitosan?
Chitosan is originally known as a marine polysaccharide. Chitosan, which can be prepared by partial deacetylation of chitin, is composed of glucosamine. Chitin is mainly present in crustaceans (shrimps, lobsters and crabs) and some other sources like fungi, corals, yeasts, diatoms sponges, mollusks and worms. Chitosan is usually obtained by treating the chitin shells of shrimp and other crustaceans with sodium hydroxide. Even though chitin is not soluble, chitosan is soluble in dilute aqueous acid solutions. (2)
Role of Chitosan in health
In a 2007 study, researchers tried to evaluate the clinical effectiveness of chitosan, as a carrier in gel form and as an active agent in the treatment of chronic periodontitis. The chitosan gel was incorporated with or without an antibiotic. According to the results of the study chitosan itself is effective as well as its combination with antibiotic in chronic periodontitis treatment because of its antimicrobial properties. (3)
Several studies have shown that dysfunctional mitochondria may play an important role in Alzheimer Disease and its related neuronal loss. Factors like environment and genetics, which are associated with Parkinson’s Disease, contribute to mitochondrial dysfunction and the pathogenesis of the disease. Thus, one of the therapeutic targets in Parkinson’s Disease is managing to battle the mitochondrial dysfunction. Chitosan has been shown to inhibit not only the mitochondrial membrane potential disruption, but also cell death (apoptosis). Therefore, chitosan and chitooligosaccharides can be used for the therapy of Parkinson’s disease. (2)
Cholesterol and Triglycerides
The first article about the hypocholesterolemic effect of chitosan in humans was published by Maezaki and colleagues (1993). Researchers reported that when 3–6 grams of chitosan/day were given to healthy males, they noticed a total serum cholesterol reduction and when the chitosan consumption was stopped, the value increased to the previous levels. Additionally, the levels of HDL-cholesterol increased significantly by the consumption of chitosan. Furthermore, scientists didn’t notice any side effects. Researchers tried to explain the mechanism of action and suggested that chitosan combined bile acids in the digestive tract, and the product was excreted into the feces. This, in turn, decreased the resorption of bile acids and the cholesterol pool in the body, leading to a reduction of the level of serum cholesterol. (4)
Moreover, several studies indicate that chitosan can lower plasma triglycerides and cholesterol levels. Additionally, it has been shown that chitosan can reduce the risk of cardiovascular diseases. In an animal study, rats were fed diets containing chitosan. Researchers reported a significant reduction in triglycerides, total cholesterol and LDL-cholesterol (bad cholesterol) levels as well as elevated HDL-cholesterol (good cholesterol) levels. This suggests that the interaction between chitosan and bile salts as well as cholesterol is adsorption, which leads to its hypocholesterolemic effect. (5)
It has been demonstrated that exposure to chitosan expedites the whole blood formation of a coagulum. Numerous studies have reported that chitosan acts as a hemostatic agent and may be used in various wound healing applications such as hemostatic bandages. Moreover, internal chitosan bandages have been used to achieve rapid hemostasis in large surgical and traumatic lacerations of the aorta, cardiac ventricles and organs like lung, kidney and liver. Recently, several chitosan-containing medical devices and bandages for the control of bleeding, are marketed in USA and Europe. Furthermore, chitosan’s capacity to induce clot formation, seems to be a promising characteristic, potentially useful for patients with coagulopathies. (5)
Tumor growth inhibition
Chito-oligosaccharides (CHOS) are prepared from chitosan either chemically or enzymatically. It has been reported since the ‘70s that CHOS have anti-tumor effects. Additionally, there is evidence for positive effects of CHOS in reducing metastasis of tumors. Researchers believe that the anti-tumor effects of CHOS are due to their inhibitory effects on angiogenesis. Angiogenesis is the formation of new capillary blood vessels from already existing blood vessels and this process is crucial for tumor formation because tumor growth and metastasis require angiogenesis when the tumor reaches a certain size. (6)
Chitosan and Bones
The main components of the bones are the bone matrix and osteoblasts. Chitosan and CHOS are known to increase the formation of osteoblasts and to contribute in the formation of bone-tissue. Moreover, the mineralization process and bone strength are dependent on Calcium. Studies have shown that CHOS increase calcium bioavailability and deposition in bones. (6)
In an animal study (2002) Okamoto and colleagues evaluated the analgesic effects of chitin and chitosan on inflammatory pain. Researchers reported that chitosan had a greater effect than chitin because of the different action mechanism of the two polymers. (7)
Chitosan and body weight
In a study of overweight and obese women, chitosan’s consumption was compared with placebo for a period of 8 weeks, without any other lifestyle modifications. The study showed decreased mean weight (1 kg) in the chitosan treatment group while there was an increase of body weight in the placebo group. (8)
Side effects and toxicity
Chitosan is generally considered to be nontoxic. Side effects are not usual, but usually they are related to the gastrointestinal system: constipation, nausea and diarrhea. Patients that are allergic to shellfish should discuss with their doctor before consuming shellfish chitosan supplements. (8)
Chitosan is a well-researched polymer with plenty of applications. It can be used as a food supplement safely and even in a very young age. Regular consumption of chitosan is beneficial and it could become a useful tool for a healthy lifestyle.
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