Chitosan by Allergy Research Group

POSSIBLY EFFECTIVE

• Hypertension. Substituting table salt with a chitosan-containing table salt may reduce blood pressure in patients with hypertension. Details: Small clinical studies in patients with prehypertension or moderate hypertension show that taking a specific product (Symbiosal) containing chitosan 3% in table salt for 8 weeks decreases systolic blood pressure compared with table salt alone when used as part of a diet containing a maximum of 3 grams sodium chloride daily (97708,97715). In adults with hypertension, this product increased the number of patients with controlled blood pressure by an additional 39% when compared with table salt alone (97715). In adults with prehypertension, this product increased the number of patients with systolic blood pressure less than 130 mmHg by an additional 67% when compared with table salt alone (97708).
• Obesity. Oral chitosan may lead to slight improvements in body weight when combined with a calorie-restricted diet in patients who are overweight or obese; however, it is unclear if this weight loss is clinically significant. Details: Meta-analyses of clinical research in overweight or obese patients show that taking chitosan 1-3 grams daily for up to one year may slightly-to-modestly reduce body weight when compared with placebo; however, the average weight loss in trials lasting up to one year is only 1 kg more than placebo according to the most recent meta-analysis (41729,92781,100170). These analyses also show that taking chitosan can slightly improve systolic and diastolic blood pressure, as well as low-density lipoprotein (LDL) cholesterol and triglyceride levels, in obese or overweight patients (92781,100170). Chitosan may only be beneficial for weight loss when combined with a calorie-restricted diet. Some of the small clinical studies included in the analyses above show that combining chitosan with a calorie-restricted diet can result in modest weight loss (9610,10022,10023,10024,10025), while taking chitosan without calorie reduction does not seem to cause clinically significant weight loss (3243,3244,9986,14314,41724). It also does not seem to significantly increase fecal fat excretion, which is the suggested mechanism of action for reducing weight (9987,10020,11045,14314).
• Postoperative recovery. Application of chitosan gel dressings after endoscopic sinus surgery may improve recovery by lowering the risk of nasal adhesions. Details: A meta-analysis of three small clinical studies shows that use of chitosan gel dressing following endoscopic sinus surgery reduces the risk of nasal adhesions by 75% when compared with saline or no dressing. The chitosan dressings did not influence swelling, crusting, or infections (97713,97714).

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Crohn disease. Oral chitosan has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: One small, uncontrolled clinical study in adults with Crohn disease shows that taking a combination of chitosan 1.05 grams and ascorbic acid daily for 8 weeks increases fecal excretion of fat, but does not improve disease activity, when compared to baseline (9609). The validity of these findings is limited by a lack of control group.
• Dental caries. While small studies suggest that use of chitosan-containing gum or mouthwash can decrease levels of cavity-causing bacteria, it is unclear if these products reduce the risk of developing dental caries. Details: One small clinical study in healthy adults shows that chewing gum supplemented with chitosan decreases the number of cariogenic bacteria in the mouth when compared with non-supplemented gum (15126). Additionally, a small crossover trial shows that rinsing with chitosan 0.5% mouthwash twice daily for 14 days can also decrease the number of cariogenic bacteria in the mouth when compared with placebo (41697). However, there is no reliable evidence that chitosan gum or mouthwash reduces the risk of developing cavities.
• Dental plaque. Small clinical studies suggest that rinsing with chitosan mouthwash may reduce plaque formation. Details: One small crossover trial shows that rinsing with chitosan 0.5% mouthwash twice daily for 14 days significantly reduces plaque formation when compared with placebo (41697). Another small clinical study in patients with dental plaque and gingivitis shows that rinsing with 10 mL of chitosan 0.5% mouthwash twice daily for 3 months reduces plaque formation when compared to baseline, with similar improvements when compared with chlorhexidine 0.2% mouthwash. However, rinsing with a combination of chitosan and chlorhexidine significantly improves plaque formation when compared with either agent alone (106521).
• Diabetic foot ulcers. It is unclear if topical chitosan is beneficial in patients with diabetic foot ulcers. Details: A small clinical study in adults with diabetic foot ulcers shows that applying a thin smear of chitosan 10% gel to the ulcer is no more effective than placebo gel for ulcer healing. Also, when chitosan 10% gel is used in combination with topical isosorbide dinitrate two sprays daily, it is no more effective than the isosorbide dinitrate spray alone (100171). It is not clear if this study was adequately powered to detect a difference between groups.
• Dry eye. It is unclear if chitosan-containing eye drops are beneficial in patients with dry eye. Details: A small clinical study in patients with dry eye shows that applying a specific eye drop (Lacrimera) containing chitosan-N-acetylcysteine 0.1% once or twice daily to the eyes for 5 days improves general symptoms of dry eye by approximately 60% when compared to baseline (97710). The validity of these findings is limited by a lack of placebo control group.
• Gingivitis. It is unclear if rinsing with chitosan mouthwash is beneficial in patients with gingivitis. Details: A small clinical study in patients with gingivitis and dental plaque shows that rinsing with 10 mL of chitosan 0.5% mouthwash twice daily for 3 months reduces gingivitis scores when compared to baseline, with similar improvements when compared with chlorhexidine 0.2% mouthwash. However, rinsing with a combination of chitosan and chlorhexidine significantly improves gingivitis scores when compared with either agent alone (106521).
• Hypercholesterolemia. Despite conflicting study results in patients with hypercholesterolemia, a meta-analysis of small clinical studies suggests that oral chitosan may slightly improve lipid levels when taken for at least 4 weeks in overweight or obese patients with or without hypercholesterolemia. Details: A meta-analysis of seven small clinical studies of obese or overweight patients with or without hypercholesterolemia shows that taking chitosan 1-4.5 grams daily for 4 weeks or longer can reduce both total cholesterol and low-density lipoprotein (LDL) cholesterol by around 6 mg/dL, increase high-density lipoprotein (HDL) cholesterol by around 1 mg/dL, and reduce triglyceride levels by around 11 mg/dL when compared with placebo (92781). However, individual studies in patients with mild hypercholesterolemia show conflicting results. Some small clinical studies show that taking chitosan 1-3 grams daily for 1-3 months does not decrease total cholesterol or LDL cholesterol (3243,9986,11044), while other studies show that taking chitosan 1.2-1.35 grams daily for 8 weeks modestly reduces total cholesterol by 4% to 10% and LDL cholesterol by about 7% when compared with placebo (11307,41693). Several clinical studies also suggest that chitosan-containing combination products seem to reduce cholesterol levels in obese patients or those with hypercholesterolemia. Combinations studied include chitosan 1.2 grams with glucomannan 1.2 grams daily for 1 month (11046); a fiber supplement containing chitosan, guar meal, ascorbic acid, and other micronutrients (10025); chitosan 240 mg, garcinia 55 mg, and chromium 19 mg once or twice daily for 4 weeks (41720); and a specific product (Tegradoc) containing chitosan 10 mg, berberine 200 mg, red yeast extract providing monacolin K 3 mg, and coenzyme Q10 10 mg daily for 12 weeks (97709). It is unclear if the positive findings associated with these combination products are due to chitosan, other ingredients, or the combination.
• Hyperphosphatemia. It is unclear if chewing chitosan-loaded gum is beneficial in patients with hyperphosphatemia who are undergoing hemodialysis. Details: One very small clinical study in patients undergoing hemodialysis with hyperphosphatemia inadequately controlled with sevelamer shows that chewing 20 mg of chitosan-loaded gum twice daily for 2 weeks reduces serum phosphorous levels by 31% when compared to baseline (92784). The validity of this finding is limited by a lack of control group. Conversely, a slightly larger, placebo-controlled clinical study in patients on hemodialysis with phosphorous levels inadequately controlled on phosphate binders shows that chewing 40 mg of chitosan-loaded gum for 30 minutes three times daily for 3 weeks does not significantly reduce serum phosphorous levels when compared with placebo (92779).
• Iron deficiency anemia. Although there has been interest in using oral chitosan for iron deficiency anemia, there is insufficient reliable information about the clinical effects of chitosan for this purpose.
• Kidney failure. It is unclear if oral chitosan is beneficial in patients with kidney failure who are receiving hemodialysis. Details: One small clinical study in patients with kidney failure receiving chronic hemodialysis shows that taking chitosan 450 mg three times daily for 12 weeks reduces elevated cholesterol levels, improves anemia, and enhances physical strength, appetite, and sleep when compared with no treatment (1942).
• Minor bleeding. Small clinical studies suggest that application of chitosan gel dressings after endoscopic sinus surgery may reduce the risk of minor post-surgical bleeding, while application of chitosan-containing gauze to skin grafts does not appear to reduce bleeding risk. Details: A meta-analysis of two small clinical studies shows that use of chitosan gel dressing following endoscopic sinus surgery increases hemostasis by 70% when compared with saline or no dressing (97714). Over 60% of patients using chitosan gel achieved hemostasis within 2 minutes compared with 17.5% of patients not using chitosan gel (97713). However, one small study in patients with skin grafts shows that using chitosan gauze (AnsCare ChitoClot Gauze, BenQ Materials Corporation) with paraffin dressing for 2 weeks does not reduce the amount of blood loss when compared with paraffin dressing alone (97711). These conflicting results might be related to the form of chitosan used or the type of surgical wound to which it is applied.
• Muscle strength. Although there has been interest in using oral chitosan for increasing muscle strength, there is insufficient reliable information about the clinical effects of chitosan for this purpose.
• Periodontitis. It is unclear if topical chitosan is beneficial in patients undergoing surgery for periodontitis. Details: A very small clinical study in patients with periodontitis undergoing dental surgery shows that applying chitosan ascorbate to the gums improves tooth mobility and pocket depths when compared to baseline (1945). The validity of these findings is limited by a lack of control group.
• Wound healing. Several small clinical studies suggest that application of chitosan-containing dressings to skin grafts improves wound healing, scar formation, and nerve regeneration. Details: One small clinical study shows that applying a chitosan mesh dressing increases healing and regeneration of the skin in the first ten days after skin graft placement and reduces itching by about 50% when compared with paraffin dressing (97707). Another small clinical study in patients receiving skin grafts after surgery, burn wounds, or skin malignancy excision shows that application of a chitosan-containing dressing to the skin graft improves wound re-epithelialization and nerve regeneration, but does not improve the rate of healing, when compared with a conventional dressing (41692). Another small clinical study in patients undergoing plastic surgery shows that applying N-carboxybutyl chitosan topically seems to promote donor site tissue regeneration and reduce scar formation when compared with control donor sites (1944). A small clinical study in adults undergoing extraction of an impacted mandibular third molar shows that applying a topical gel (Bexident Post, ISDIN) containing chitosan, allantoin, dexpanthenol, and chlorhexidine as 10 mL three times daily for ten days increases the rate of good wound healing by an additional 52% and 36% after 7 and 14 days, respectively, when compared with no gel. However, this chitosan-containing gel does not appear to reduce postoperative pain or swelling (97712). It is unclear if these findings are due to chitosan, other ingredients, or the combination. More evidence is needed to rate chitosan for these uses.

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POSSIBLY SAFE. ..when used orally, short-term. Chitosan has been used with apparent safety in clinical studies at a dose of up to 1.35 grams daily for up to 3 months (1942,9609,9610,10022,10023,10024,10025,11307,13171,14314)(15126,92781,97708). ...when used topically, short-term (1944,1945,4269,4270,97712,106521).

PREGNANCY AND LACTATION:
Insufficient reliable information available; avoid using.

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ACYCLOVIR (Zovirax) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Chitosan can reduce the absorption of acyclovir, potentially increasing the risk for treatment failure.  Details Clinical research in humans shows that taking chitosan along with acyclovir 200 mg reduces acyclovir absorption. Concomitant administration of chitosan 400 mg or 1000 mg reduced the acyclovir area under the curve (AUC) and peak plasma concentration by about 30% and 40%, respectively, compared with control. Concomitant administration with chitosan 1000 mg also increased time to peak concentration from 1 hour to 2 hours (92780). In vitro research suggests that the mechanism for reduced absorption is due to acyclovir entrapment in chitosan-mucus complexes, which reduces intestinal absorption (112352).

WARFARIN (Coumadin) Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, chitosan might increase the risk of bleeding when taken with warfarin.  Details In a case report, a patient taking warfarin had a significantly increased international normalized ratio (INR) after starting chitosan 1200 mg daily. The INR normalized after chitosan was discontinued and vitamin K was administered. The patient once again started taking chitosan and again had a significant increase in INR. The INR stabilized again once chitosan was discontinued (15909). Researchers theorize that this interaction might occur because chitosan decreases absorption of fat-soluble vitamins, including vitamin K, which could increase the anticoagulant effect of warfarin.

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General ...Orally and topically, chitosan seems to be well tolerated, short-term.
Most Common Adverse Effects:
Orally: Constipation, diarrhea, flatulence, epigastric discomfort, and nausea.

Dermatologic ...In one clinical trial, a subject with kidney failure reported itching during 12 weeks of oral chitosan treatment (1942). It is not clear if this was related to the underlying renal failure or the use of oral chitosan.

Gastrointestinal ...Orally, chitosan has been reported to cause epigastric discomfort, constipation, flatulence, diarrhea, nausea, and dryness of the throat (1942,3243,9986,11307,14314,41688,92781,100170). Excessive discharge of fat in the feces, also known as steatorrhea, has been reported with chitosan therapy (41724,41726). Theoretically, chitosan may alter the normal intestinal flora via antimicrobial activity, which could interfere with lipid digestibility and bile acid metabolism, leading to the growth of resistant pathogens (41687,41709,41725).

Musculoskeletal ...Orally, chitosan has been reported to cause swollen heels and wrists in two patients (41688).

Neurologic/CNS ...Headaches have been reported in patients taking oral chitosan (41688).

Ocular/Otic ...Topically, an eye drop containing chitosan-N-acetylcysteine has been reported to cause itching and irritation of the eyes (97710).

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