Chitosan

Chitosan is a biocompatible, naturally occurring polysaccharide obtained through the partial deacetylation of chitin – the main component of the shells of crustaceans such as crabs, shrimp, or lobsters. Chitin is the second most abundant natural polymer on Earth after cellulose. Through the conversion into chitosan, the otherwise insoluble chitin becomes water-soluble and thus versatile in its uses – both industrially and in the medical and nutritional field. Due to its positive charge (cationic character), chitosan stands out clearly from other polysaccharides. It can bind negatively charged substances such as fats, bile acids, heavy metals, or microorganisms, which explains its use in wastewater treatment, wound care, and especially as a dietary aid in fat binding. In addition, chitosan is considered biodegradable, well tolerated, and exhibits low toxicity – properties that make it an interesting candidate for drug carriers, dietary supplements, and cosmetic products.

What benefits does chitosan offer for health?** Chitosan is being studied and used in many ways in health research and industry. More research is needed to be able to draw definitive conclusions and fully understand its effects. Here is a selection of the most frequently discussed benefits:

  • Fat binding, cholesterol lowering, and weight management: Chitosan is said to bind fat in the intestine and has therefore been tested as a remedy for high cholesterol levels. One study found that taking chitosan supplements lowered the cholesterol levels of study participants; other studies, however, showed only minimal to no results (1,2).
  • Gut health & microbiota: Initial evidence suggests that chitosan could positively influence the composition of the gut flora and promote the growth of beneficial bacteria (3,4,5).
  • Antioxidant and anti-inflammatory effects: Studies point to both anti-inflammatory and antioxidant effects of chitosan and chitooligosaccharides, respectively (5,6).
  • Antimicrobial effect: Studies indicate that chitosan could reduce plaque, increase saliva secretion, and exert an antibacterial effect that could be effective in the treatment of chronic periodontitis (2).
  • Heavy metal binding & detoxification: Chitosan has a reputation for being able to form complexes with heavy metals and thus channel them out of the body, which is discussed in environmental medicine (7,8).

How does chitosan work in the body?** Chitosan exerts its effect mainly in the gastrointestinal tract. Due to its positive charge, it binds negatively charged molecules – including fats, bile acids, toxins, or microparticles. These bound substances are then excreted via the stool. In contrast to many other dietary fibers, chitosan is fermented by the gut flora only to a very small extent. In addition, it can influence the absorption of fat-soluble substances, which can be used in a targeted therapeutic or dietary way.

Are there risks or side effects?

  • Allergy risk with shellfish allergy: Since chitosan is usually obtained from crustacean shells, people with a corresponding allergy should be cautious.
  • Nutrient binding: In addition to fats, chitosan could also bind fat-soluble vitamins (e.g., vitamins D, E, K, A), which should be taken into account with long-term use.
  • Digestive discomfort: In rare cases, bloating or mild constipation can occur, especially at higher doses.
  • Often not suitable for a vegan diet: Classic chitosan comes from an animal source; however, there are plant-based alternatives made from fungi.

Conclusion Chitosan is a versatile natural polymer with interesting properties for medicine, nutrition, and cosmetics. Its ability to bind various substances is particularly interesting and continues to be investigated in various scientific research projects. Despite its natural origin, it should always be taken mindfully with regard to possible nutrient interactions and allergies. Overall, more research is still needed to conclusively understand the effects of chitosan.

Sources:

  1. Moraru, C., Mincea, M. M., Frandes, M., Timar, B., & Ostafe, V. (2018). A Meta-Analysis on Randomised Controlled Clinical Trials Evaluating the Effect of the Dietary Supplement Chitosan on Weight Loss, Lipid Parameters and Blood Pressure. Medicina (Kaunas, Lithuania), 54(6), 109. https://doi.org/10.3390/medicina54060109
  2. "Chitosan." Drugs.com, 20 May 2024, www.drugs.com/npp/chitosan.html. Accessed 28 Sept. 2024.
  3. Edo, G. I., Mafe, A. N., Ali, A. B. M., Akpoghelie, P. O., Yousif, E., Apameio, J. I., Isoje, E. F., Igbuku, U. A., Garba, Y., Essaghah, A. E. A., Ahmed, D. S., Umar, H., & Ozsahin, D. U. (2025). Chitosan and its derivatives: A novel approach to gut microbiota modulation and immune system enhancement. International Journal of Biological Macromolecules, 289, 138633. https://doi.org/10.1016/j.ijbiomac.2024.138633
  4. T. R. Rúnarsdóttir, S. Skírnisdóttir, H. Thors, H. Harðardóttir, K. F. Corral-Jara, A. M. Klonowski, Þ. I. Halldórsson, V. Þ. Marteinsson, M. Guðjónsdóttir, The Effect of Chitosan Supplementation on the Gut Microbiota and Various Health Factors in Icelandic Females: A Placebo-Controlled, Double-Blind, Randomized Trial. Mol. Nutr. Food Res. 2025, e70137. https://doi.org/10.1002/mnfr.70137
  5. Guan, Z., & Feng, Q. (2022). Chitosan and Chitooligosaccharide: The Promising Non-Plant-Derived Prebiotics with Multiple Biological Activities. International journal of molecular sciences, 23(12), 6761. https://doi.org/10.3390/ijms23126761
  6. Naveed, M., Phil, L., Sohail, M., Hasnat, M., Baig, M. M. F. A., Ihsan, A. U., Shumzaid, M., Kakar, M. U., Khan, T. M., Akabar, M., Hussain, M. I., & Zhou, Q.-G. (2019). Chitosan oligosaccharide (COS): An overview. International Journal of Biological Macromolecules, 129, 827–843. https://doi.org/10.1016/j.ijbiomac.2019.01.192
  7. Sutirman, Z. A., Sanagi, M. M., Abd Karim, K. J., Wan Ibrahim, W. A., & Naim, A. (2018). Chitosan-based adsorbents for the removal of metal ions from aqueous solutions. Malaysian Journal of Analytical Sciences, 22(5), 839–850. https://doi.org/10.17576/mjas-2018-2205-11
  8. Omer, A. M., Dey, R., Eltaweil, A. S., Abd El-Monaem, E. M., & Ziora, Z. M. (2022). Insights into recent advances of chitosan-based adsorbents for sustainable removal of heavy metals and anions. Arabian Journal of Chemistry, 15(2), 103543. https://doi.org/10.1016/j.arabjc.2021.103543