Chitosan, made from the exoskeleton of shellfish, is an unusual fiber source in that it contains both carbohydrates and protein and comes not from plants but from animals. Chitosan binds to dietary fats and can block absorption of fats, leading to lower cholesterol levels and weight loss. Not all clinical studies back these claims, however. Several potentially serious health risks are associated with chitosan use. Do not take chitosan without your doctor's approval if you take blood-thinning medications or if you're allergic to shellfish.
Allergic Potential
Chitosan comes from crustaceans such as shrimp, lobster and clams -- all foods with a high potential for allergic reaction, according to MayoClinic.com. If you have a seafood allergy and take chitosan, you could have an allergic reaction. Around 7 million Americans have a shellfish allergy, and 60 percent don't develop symptoms until they're adults, the American Dietetic Association says. Signs and symptoms of allergy to shellfish include hives, rash, shortness of breath, wheezing, tingling in the mouth or throat, difficulty breathing, stomach pain, diarrhea, nausea or vomiting. An allergic reaction can get worse over time; stop taking chitosan immediately if you experience any of these signs or symptoms. Anaphylactic shock may occur, with dizziness, low blood pressure, circulatory collapse, coma and death in rare instances.
Blood-thinning and Clotting Actions
Chitosan appears to have several different clotting effects, depending on its use. Chitosan causes blood to clot more rapidly than it normally would when used externally. However, when taken as a supplement, chitosan may increase the blood-thinning effects of anticoagulants such as warfarin, Drugs.com reports. People who take anticoagulants should talk with their physician before taking chitosan supplements.
Nutrient Loss
Chitosan appears to bind to fatty acids and could also bind essential fatty acids such as omega-3 fish oils as well as other vitamins and minerals. While this effect does not appear to be strong enough to result in weight loss in most clinical studies, it could result in a deficiency of essential nutrients. For this reason, pregnant women who need extra nutrition should not take chitosan, William Hennen, Ph.D., reports. On the other hand, chitosan's phosphate-binding properties could benefit people undergoing dialysis who often have elevated phosphate levels, pharmacist John Russo reports. However, clinical studies to evaluate the effects are needed.
Considerations
When taking any potentially allergenic supplement such as chitosan, start with a low dose and watch for potential side effects. If taking chitosan for weight loss, be aware that it appears to have benefit only when combined with a low-calorie diet, according to Shawn Talbott, M.S., author of "The Health Professional's Guide to Dietary Supplements."
References
- "Journal of the American College of Nutrition"; Safety Aspects and Cholesterol-Lowering Efficacy of Chitosan Tablets; Niina S. Tapola, MSc, RD, et al.; February 2008
- "The Health Professional's Guide to Dietary Supplements"; Shawn M. Talbott, Kerry Hughes; Lippincott Williams & Wilkins; September 2006
- American Dietetic Association: Shellfish Allergy Guide
- Memorial Sloan-Kettering Cancer Center; Chitosan; April 2011
- MayoClinic.com; Shellfish Allergy; June 2009
- The C.A.M. Report; Chitosan Lowers Phosphate Levels in Kidney Disease; John Russo, PharmD; February 2009
