The Health Benefits of Chitosan

What Studies Say About Potential Weight Loss

Pre cooked shrimps in bowl
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Chitosan is a dietary supplement made from the shells of crustaceans such as crabs, shrimp, and lobster. Often marketed as a natural weight loss aid, supplement manufacturers claim that chitosan can fight fat absorption. However, there is little scientific support for the weight loss benefits of chitosan.

Health Benefits

The most widely promoted health benefit of chitosan is to boost fat loss. Supplement makers often claim that chitosan binds to fat in the body and allows you to excrete more of it, thereby reducing the amount of fat your body stores.

But the evidence to support this claim is lacking.

For a report published in the Cochrane Database of Systematic Reviews in 2008, researchers reviewed 15 clinical trials (with a total of 1,219 participants) that tested the effects of chitosan on adults who were overweight or obese. Compared to participants given a placebo, study members treated with chitosan appeared to lose significantly more weight and experience beneficial changes in cholesterol levels and blood pressure. However, the report's authors note that many of the reviewed trials were of poor quality. Furthermore, findings from the high-quality trials suggest that chitosan may have a minimal, insignificant effect on weight.

A larger report (published in the American Journal of Clinical Nutrition in 2004) also indicates that chitosan may not be useful for weight loss. Looking at five previously published reviews and meta-analyses (as well as 25 additional clinical trials), the report's authors found "no evidence beyond a reasonable doubt that any specific dietary supplement is effective for reducing body weight." Supplements highlighted in the report included chitosan and yerba mate.

Possible Side Effects

Some research shows that chitosan may cause certain adverse effects including constipation and upset stomach. Chitosan may also reduce the absorption of essential nutrients such as calcium and vitamins A, DE, and K. In addition, chitosan may cause allergic reactions in people with shellfish allergies.

Due to a lack of research, little is known about the safety of regular or long-term use of chitosan. 

Dosage and Preparation

There is not enough scientific data to provide a recommended dose of chitosan. In clinical trials, various doses have been studied.

For example, in studies examining the effects of chitosan on weight loss, subjects took one gram 2-4 times daily with a calorie-restricted diet. In other trials, a dose of four fiber supplement tablets containing chitosan, guar meal, ascorbic acid, and other micronutrients has been used twice daily for four weeks.

The appropriate dose for you may depend on factors including your age, gender, and medical history. Speak to your healthcare provider to get personalized advice.

What to Look For

Due to the lack of scientific support for its use, chitosan cannot be recommended for weight loss. In order to lose weight, it's important to follow a healthy diet (including a wide variety of vegetables and fruits) and stick with an exercise program that combines aerobic activity with strength training. Improving your sleep hygiene and managing your stress levels may also help promote weight loss.

Also, it's important to keep in mind that supplements haven't been tested for safety and dietary supplements are largely unregulated. In some cases, the product may deliver doses that differ from the specified amount for each herb. In other cases, the product may be contaminated with other substances such as metals.

Lastly, the safety of supplements in pregnant women, nursing mothers, children, and those with medical conditions or who are taking medications has not been established. You can get further tips on using supplements, but it's important to note that self-treating a condition and avoiding or delaying standard care may have serious consequences. If you're considering using chitosan, make sure to consult your physician first.

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  1. Jull AB, Ni Mhurchu C, Bennett DA, Dunshea-Mooij CA, Rodgers A. Chitosan for overweight or obesity. Cochrane Database Syst Rev. 2008;(3):CD003892. doi:10.1002/14651858.CD003892.pub3

  2. Pittler MH, Ernst E. Dietary supplements for body-weight reduction: a systematic review. Am J Clin Nutr. 2004;79(4):529-536. doi:10.1093/ajcn/79.4.529

  3. Mhurchu CN, Dunshea-Mooij C, Bennett D, Rodgers A. Effect of chitosan on weight loss in overweight and obese individuals: a systematic review of randomized controlled trials. Obes Rev. 2005;6(1):35-42. doi:10.1111/j.1467-789X.2005.00158.x

  4. Moraru C, Mincea MM, Frandes M, Timar B, Ostafe V. 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). 2018;54(6). doi:10.3390/medicina54060109

Additional Reading
  • Memorial Sloan-Kettering Cancer Center. Chitosan. Updated November 26, 2019.