IngredientsChemically, chitosan is predominantly a polymer of β-1,4-linked 2-amino-2-deoxyglucose monomers. Chitosan is a natural polysaccharide that consists of glucosamine and N-acetylglucosamine copolymers. More precisely, its chemical structure can most simply be described as a co-polymer of glucosamine and acetyl-glucosamine.
Chitosan is not a single molecular entity, but comprises polymeric chains of various lengths. The degree of deacetylation (DD%) can be determined by NMR spectroscopy, and the degree of deacetylation in commercially available chitosan ranges from 60 to 100%. The DD value of a polymer identifies whether it is chitosan or chitin; if a polymer has a DD value of more than 60%, it is considered to be chitosan. On average, the molecular weight of commercially produced chitosan is 3,800–20,000 daltons.
Chitosan contains three functional groups: C2-NH2, C3-OH, and C6-OH. C2-NH2 is highly reactive for fine modifications and is the most common modifying group in chitosan. As a natural cationic biopolymer in its dissolved form (pH < 5.7), chitosan possesses a positive charge, giving rise to versatile uses based on its anti-microbial, gelling, and film-forming properties.
Chitosan is a type of biopolymer that can be derived from various natural sources, including animals and marine organisms. When prepared from a natural source, the usual natural source is chitin, a major constituent of the shells of crabs, shrimp, and other arthropods. Chitin is chemically a polymer comprising β-1,4-linked 2-acetamino-2-deoxyglucose monomers. On a commercial scale, chitosan is mainly obtained from crustacean shells rather than from fungal and insect sources.
Significant efforts have been devoted to commercializing chitosan extracted from fungal and insect sources to completely replace crustacean-derived chitosan. Research groups and companies have been investigating the advantages of using fungal chitosan, as its production can be sustainable using residues from the agricultural sector or industry as a culture medium, and there are several applications especially in the biomedical area due to the standardization of production and reduction in side effects, particularly allergens and immune system sensitizers. Unlike other plant-based bioplastics such as cellulose and starch, the main natural sources of chitosan come from marine environments and do not compete for land or other human resources.
After isolation of chitin from its natural source, it is treated in a manner to cause hydrolysis of the acetamido group without cleavage of the sugar-sugar bonds, typically through alkaline hydrolysis. Alkaline treatment is typically used to deproteinize chitin. When determining quality, molecular weight, crystallinity, and degree of deacetylation of chitosan are considered, as biocompatibility, bioadhesive properties, solubility, and polycationic character are all based on these traits.
Chitosan can be molded into a variety of forms, such as powder, film, sphere, gel, and fiber. Chitosan is marketed in tablet form as a "fat binder." The pH-dependent solubility of chitosan allows it to be formed into various shapes — including beads, films, and membranes — using aqueous processing. In addition to oral dietary supplement tablets and capsules, chitosan is used in topical wound dressings, mouthwash solutions, chewing gums, ophthalmic solutions, and injectable or implantable biomedical devices.
Chitin was first discovered in mushrooms by Professor Henri Braconnot of France in 1811. Antoine Odier was the first to use the product in 1823. The name "chitin" emerged in the 1830s, when the substance was isolated in insects. Chitosan itself was discovered in 1859 by Professor C. Rouget.
In the 1930s and 1940s, chitosan polymers attracted considerable attention, as evidenced by approximately 50 patents secured during that time; however, lack of adequate manufacturing facilities and competition from synthetic polymer producers restricted commercial development. Revived interest in the 1970s encouraged the need to better utilize shellfish shells.
The word "chitin" derives from the Greek etymology, meaning "tunic" or "envelope." The natural biopolymer chitin and its deacetylated product chitosan are found abundantly in nature as structural building blocks and are used in all sectors of human activities including materials science, nutrition, health care, and energy.
Chitosan has already been used as a primary source for several health-related applications, with products existing in localized markets in Asia (Japan, China, India, Korea) and Europe (Iceland, Germany). It is approved for dietary applications in Japan, Italy, and Finland. Systematic use of chitosan as a dietary supplement in East Asian markets — particularly Japan — grew substantially in the 1980s and 1990s, prior to its broader international commercialization as a weight management and cholesterol-lowering supplement.
Positively charged amino groups on chitosan bind to negatively charged molecules such as fatty acids, lipids, and bile acids, after which they are excreted from the body rather than being systemically absorbed or reabsorbed. Fat complexation (entrapment) is a function of chitosan's solubility at an acidic pH and insolubility at a basic pH: soluble chitosan mixes with fat in the stomach and subsequently forms a semi-solid emulsion under basic pH conditions in the small intestine, and this chitosan-fat emulsion is resistant to digestion and absorption.
Chitosan is not hydrolysed by human digestive enzymes and behaves as a dietary fibre. As a source of dietary fiber, chitosan can be degraded by the gut microbiota producing short-chain fatty acids (SCFAs); it can therefore modulate gut bacteria and have a positive effect on colonic health.
Chitosan has been described as biodegradable, nontoxic, non-immunogenic, and biocompatible, with properties similar to cellulose.
Orally administered chitosan binds fat in the intestine, blocking absorption, and has been shown to lower blood cholesterol in animals and humans. However, the precise mechanism is contested. Hypocholesterolemic effects from chitosan in murine models were not attributed to reduced cholesterol absorption efficiency or increases in fecal sterol output, ruling out a major bile acid-binding capacity; the more likely scenario is that the fiber's influence on satiation and satiety reduces food intake and therefore cholesterol. Human studies suggest that it is unlikely that chitosan binds fat in the intestines and could therefore not support this purported mechanism of action. The fat-binding mechanism, while widely promoted, remains mechanistically unresolved in humans.
Chitosan has the ability to adhere to fibrinogen, which produces increased platelet adhesion, causing clotting of blood and hemostasis. The high positive charge on chitosan can stimulate erythrocyte adhesion, fibrinogen adsorption, and platelet activation, rendering it an excellent hemostatic agent. Topical application of chitosan enhances wound healing by stimulation of granulation tissue; possible mechanisms include formation of a gel-like fibronectin matrix that facilitates inward epithelial cell migration and the formation of heparin-chitosan complexes that activate growth factors that bind to stabilized heparin.
Chitosan has high biocompatibility, biodegradability, and antimicrobial, hemostatic, wound healing, and immunomodulatory activities. Chitosan may have other properties conducive to wound healing, including antibacterial and antifungal activity, which remain under preliminary research.
Chitosan, as a potentially indigestible oligosaccharide for the host, can be metabolized by the gut microbiota and influence gut microbial composition, enhancing the production of SCFAs and bile acids. Evidence highlights the inhibition of Lactobacillus and Bifidobacterium production after administration of chitosan — a counterintuitive finding, as these are generally considered beneficial genera. The net clinical implications for gut health require further investigation.
Chitosan, a commonly used dietary supplement, is believed to have the potential to decrease body weight by binding to dietary fats and decreasing their absorption. The clinical evidence for this application has been extensively reviewed.
The most-cited systematic review, published in Obesity Reviews (Ni Mhurchu et al., 2005), analyzed 14 randomized controlled trials (RCTs). Analyses involving all trials indicated that chitosan preparations result in a small but statistically significant greater reduction in body weight (weighted mean difference −1.7 kg; 95% confidence interval −2.1 to −1.3 kg, P < 0.00001) compared with placebo. However, analyses restricted to high-quality studies showed that reductions in weight were less (−0.6 kg, P = 0.11) than in lower quality studies (−2.3 kg, P < 0.00001), and results obtained from high-quality trials indicate that the effect of chitosan on body weight is minimal and unlikely to be of clinical significance.
A subsequent Cochrane-registered meta-analysis (Jull et al., 2008) compared and reviewed 15 randomized controlled trials and reported evidence that chitosan was more effective than a placebo in the treatment of overweight and obesity, high blood pressure, and slightly effective for lowering total cholesterol and triglycerides; the study included 1,219 patients with treatment duration of 4–24 weeks. Both systematic reviews noted that results of several included trials should be interpreted with caution due to their poor quality and unsuccessful correspondence with their authors, and that overall results from high-quality trials only demonstrated minimal effect from chitosan on body weight.
A 2018 meta-analysis (Moraru et al., published in Medicina) searched MEDLINE and the Cochrane Library up to December 2017. A total of 14 RCTs were used to assess the effect on body weight, serum lipids, and blood pressure; the usage of chitosan as a dietary supplement up to 52 weeks seems to slightly reduce body weight (−1.01 kg, 95% CI: −1.67 to −0.34).
A 2024 systematic review and meta-analysis published in Food Science & Nutrition (Kholdebarin et al.) included 19 RCTs with 21 effect sizes, searching PubMed/Medline, Scopus, and ISI Web of Science using a random-effects method. The combined analysis showed that chitosan supplementation significantly reduced body weight (WMD = −0.79 kg; 95% CI, −1.30 to −0.29; p = 0.002). Due to conflicting results from various studies, however, the review concluded that further research is needed.
An earlier single-blind, placebo-controlled RCT (90 days, fungal-origin chitosan) found mean changes in body weight of −1.78 ± 1.37 kg at day 45 and −3.10 ± 1.95 kg at day 90 in the chitosan group, which were significantly different (p < 0.0001) compared to placebo, with BMI decreased by 10.91 fold compared to placebo after 90-day administration. Lipid levels were unaffected and all adverse events were mild in nature and unrelated to study treatment, and chitosan from fungal origin was able to reduce mean body weight up to 3 kg during the 90-day study period.
Evidence strength summary (weight loss): Multiple meta-analyses of RCTs exist, but high-quality trials consistently show only minimal, arguably not clinically significant, weight reduction. Results from lower-quality trials are larger but unreliable. The overall evidence quality is weak to modest.
Considering parameters beyond weight, the meta-analysis by Moraru et al. (2018) found the most significant improvement in systolic and diastolic blood pressure: −2.68 mm Hg (95% CI: −4.19 to −1.18) and −2.14 mm Hg (95% CI: −4.14 to −0.14) in favour of chitosan versus placebo. The authors concluded that the usage of chitosan as a dietary supplement can lead to a slight short- and medium-term effect on weight loss and improvement of serum lipid profile and cardiovascular factors.
In an earlier RCT in hemodialysis patients, ingestion of chitosan effectively reduced total serum cholesterol levels (from 10.14 ± 4.40 to 5.82 ± 2.19 mM) and increased serum haemoglobin levels (from 58.2 ± 12.1 to 68 ± 9.0 g L−1).
Regarding regulatory recognition, in the EFSA 5th batch of Article 13.1 health claims released in June 2011, EFSA issued a positive evaluation related to chitosan and maintenance of normal blood LDL-cholesterol. EFSA concluded that a cause-and-effect relationship has been established between the consumption of chitosan and maintenance of normal blood LDL-cholesterol concentrations, and that 3 g of chitosan should be consumed daily to obtain the claimed effect.
Some clinical trials support cholesterol-lowering use, but long-term effectiveness is unknown.
Evidence strength summary (cholesterol): Moderate. EFSA has issued a positive opinion for an LDL-cholesterol maintenance claim at ≥3 g/day, but the effect size across trials is modest and long-term data are sparse.
A systematic review conducted by Jull et al. provided conclusive evidence that chitosan significantly lowered systolic blood pressure (WMD: −6 mmHg, 95% CI: −7 to −5; P < 0.00001) and diastolic blood pressure (WMD: −3 mmHg, 95% CI: −4 to −2; P < 0.00001). Evidence from experimental studies has indicated that administration of chitosan could prevent the development of hypertension in spontaneously hypertensive rats; however, many clinical trials in humans have small sample sizes and convey mixed and inconclusive results.
Evidence strength summary (blood pressure): Preliminary to moderate. Systematic review data indicate statistically significant but small reductions. Many individual trials are underpowered. Animal data are supportive. Long-term human evidence is lacking.
The effects of chitosan were investigated in 80 patients with renal failure undergoing long-term stable hemodialysis; after a 1-week control period, half were fed 30 chitosan tablets (45 mg chitosan/tablet) three times a day. Ingestion of chitosan effectively reduced total serum cholesterol levels and increased serum haemoglobin levels, and significant reductions in urea and creatinine levels in serum were observed after 4 weeks of chitosan ingestion.
A subsequent study on oxidative stress in hemodialysis patients found that ingestion of chitosan over a 12-week period resulted in a significant decrease in serum indoxyl sulfate and phosphate levels compared with levels prior to the study; chitosan also resulted in a lowered ratio of oxidized to reduced albumin and a decrease in advanced oxidized protein products; in vitro studies showed chitosan solutions bound 38.5% of the indoxyl sulfate and 17.8% of the phosphate.
Some research suggests that taking chitosan by mouth may reduce high cholesterol, help to correct anemia, and improve physical strength, appetite, and sleep in people with kidney failure who are receiving long-term hemodialysis. Limited clinical data are available regarding efficacy for anemia or chronic renal failure.
Evidence strength summary (renal failure): Preliminary. A small number of human studies report benefits in hemodialysis patients, but the evidence base is limited in size and methodological rigor.
In a randomized, double-blind intervention trial (n = 51) in Koreans with prediabetes, 12-week supplementation with chitosan (1,500 mg/day) resulted in statistically significantly improved blood glucose at 30 and 60 minutes, glycated hemoglobin (HbA1c), change in body fat percentage, and waist circumference compared with the placebo group. No significant differences were noted between groups in the level of change of inflammatory biomarkers (IL-6, TNF-alpha).
In a separate single-blind RCT, chitosan was also able to reduce HbA1c levels (below 6%) in subjects who had initially higher values.
Evidence strength summary (blood glucose): Very preliminary. Only a small number of clinical trials have specifically examined glucose control, and replication in larger studies is needed before conclusions can be drawn.
Due to its biological properties, chitosan has been employed in research and commercial products in wound healing management, including wound dressings and bandages, implantable device systems such as orthopedic and periodontal composites, scaffolds for tissue regeneration, and drug- and DNA-delivery systems. Chitosan-containing products are currently available on the medical market, typically as US FDA Class I medical device wound dressings or "bandages" to promote wound healing.
Compared to regular gauze dressing, chitosan dressing accelerated platelet aggregation (indicated by the lower ratio of prothrombin time and activated partial thromboplastin time), exhibited outstanding blood absorption ability, inhibited bacterial growth up to 8 days post-surgery, and 16S rRNA-based sequencing revealed that the chitosan dressing effectively protected the wound from microbial infection and promoted the growth of probiotic microbes, thereby improving skin immunity and promoting wound healing.
Lab studies and a clinical trial support the use of chitosan topically for improved wound healing.
Evidence strength summary (wound healing): Moderate for topical/medical-device use. FDA clearance as a Class I wound dressing has been obtained, and both in vitro and some human evidence support hemostatic and antimicrobial properties. Mechanistic evidence is clearer than it is for oral uses.
There is some evidence that a chewing gum containing chitosan or a mouthwash containing chitosan can decrease the number of cavity-causing bacteria in the mouth; however, there is no reliable evidence that these products actually prevent cavities. Early research suggests that rinsing with a chitosan mouthwash for 2 weeks reduces plaque formation.
Evidence strength summary (oral health): Preliminary. Small clinical studies suggest antimicrobial effects in the oral cavity, but evidence for clinically meaningful outcomes such as cavity prevention is absent.
Early research shows that taking a combination of chitosan and ascorbic acid by mouth might help people with Crohn's disease. Evidence is very limited and confined to preliminary studies.
Evidence strength summary (Crohn's disease): Insufficient. Only early-stage data exist; no robust RCTs have been conducted.
Chitosan has been administered in cholesterol reduction and weight loss clinical studies in wide-ranging doses of 0.24 to 15 g daily (median, 3.7 g/day) for 4 to 24 weeks.
Chitosan is considered Generally Recognized as Safe (GRAS) as a food additive at the level of "self-affirmed" by various manufacturers of chitosan. From most studies reported, it appears that chitosan shows minimal toxic effects, which justifies its selection as a safe material in drug delivery. Clinical trials report few adverse events; at 6.75 g/day for 8 weeks, no adverse hematological effects were found for chitosan.
Reported adverse events include constipation and gastrointestinal distress. Common side effects of chitosan include constipation, flatulence (gas), bloating, nausea, and abdominal cramping.
As chitosan products are derived from shellfish or mushrooms, patients who are allergic to these substances should use chitosan with caution. Patients allergic to shellfish or mushrooms should use related supplements with caution.
Warfarin (anticoagulant): In a case report of an 83-year-old man with hypertensive cardiovascular disease, type 2 diabetes mellitus, and chronic atrial fibrillation maintained on warfarin, chitosan appeared to increase the anticoagulant effect of this drug. Potentiation of the anticoagulant effect of warfarin was reported in a patient receiving chitosan 2.4 g/day.
Mechanism of anticoagulant interaction: Chitosan can decrease GI absorption of vitamin K, enhancing anticoagulant effects.
Fat-soluble vitamins and vitamin E: Chitosan decreases levels of vitamin E by inhibition of GI absorption; this applies only to the oral forms of both agents. By extension, prolonged chitosan supplementation may reduce absorption of other fat-soluble vitamins (A, D, K) through the same fat-binding mechanism.
Antithrombotic agents: Chitosan increases the effects of antithrombin alfa through mechanisms related to its anticoagulant-enhancing activity.
Information regarding safety and efficacy in pregnancy and lactation is lacking. Chitosan has been administered to patients with renal failure undergoing long-term hemodialysis without any apparent adverse events.
In the United States, chitosan is widely marketed (without FDA approval) as a weight loss agent that binds fats and prevents their absorption. It has been approved by the FDA for use in wound dressings. In the European Union, EFSA issued a positive evaluation for the health claim linking chitosan to maintenance of normal blood LDL-cholesterol concentrations under Regulation (EC) No 1924/2006.
Health conditions that Chitosan may help support.
Chitosan, a deacetylated chitin derivative from crustacean shells and fungal cell walls, has been studied as a GI mycotoxin binder. Its positively charged amino groups at GI pH enable ionic interactions with mycotoxin molecules. It is used as microchitosan in commercial mycotoxin binder formulas for supporting ochratoxin removal and reducing fungal burden, and cell wall polysaccharides related to chitosan are mechanistically central to probiotic yeast mycotoxin binding.
Chitosan, a cationic polysaccharide derived from chitin, supports tooth remineralization by electrostatically adhering to negatively charged enamel surfaces, modulating acid penetration, inhibiting cariogenic bacteria, and serving as an organic scaffold for hydroxyapatite crystal nucleation. Multiple in vitro and nanoparticle studies document its protective and remineralizing effects.
Chitosan is a biocompatible aminopolysaccharide derived from chitin with well-documented wound-healing properties. It promotes granulation tissue formation, fibroblast proliferation, and has antimicrobial activity. Multiple in vitro, in vivo, and clinical studies support its use as a wound dressing material.
Body systems that Chitosan may help support.
Go back