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Becca Goodyear



What is Chitosan?

                 Claims of the Companies


                 Benefits of Weight Loss         

                 Medical Studies



What is Chitosan? 

Chitosan is a “modified carbohydrate polymer derived from the chitin component

of the shells of crustacean, such as crab, shrimp, and cuttlefish.”

The chitin is “deproteinized, demineralized and de-acetylated” (Razdan, A., and Pettersson, D 1996, 387).  It is a dietary fiber, meaning that it cannot be digested by the digestive enzymes of a person (Razdan, A., and Pettersson, D. 1996).  Chitosan is composed of a NH4+ (ammonium) group attached to a polyglucosamine chain.  


Claims of the Companies



What do the companies selling the Chitosan claim about their product?



The companies claim that the purpose of Chitosan is to help a person lose weight.  Along with aiding a person in losing weight, they claim that Chitosan reduces high cholesterol, reduces high blood pressure, increases the absorption of calcium, eliminates heartburn, alleviates the symptoms of IBS, and kills Candida, yeast in the colon that causes cancer.

            Companies selling Chitosan claim that some patients have lost 8% of their body fat in 4 weeks, that it reducesblood cholesterol by 66%, that it has 55% greater fat absorption than other fibers, that it lowers the LDL (bad) cholesterol while increasing the HDL cholesterol, and it decreases the risk of colon cancer.  It has also been related to slowing down the increase in blood glucose, which in turn controls hunger.  The Grassroots Natural Products claims “Chitosan is so attracted to fat, that it actually absorbs six to ten times its own weight in fat.”


How do the companies selling Chitosan claim that it works?


The companies claim that chitosan works by absorbing fat intake in the stomach before it is metabolized.  This inhibits it from being broken down and taken through the blood stream.  Chitosan is a fiber made up of positively charged molecules.  The chitin, which is in the Chitosan, has been referred to as “‘an unstable amino polysaccharide molecule with a very strong positive (pH) polarity.’”  When the negatively charged fats and lipids enter the body, they attract with the Chitosan, and the Chitosan absorbs the fat so it cannot enter the bloodstream.  Instead, the mass of the fat and the Chitosan goes through the small intestine where it binds with bile acids.  Because of the acids in the small intestine, the pH becomes more acidic.  The mass then forms an “insoluble gel consisting of Chitosan, bile acids, bound lipids and cholesterol.”  It is then passed through the large intestine, and is then excreted from the body.  By excreting the fat and by not passing through the circulatory system, fat does not build up through out the body, and therefore weight is not gained.  Companies also claim that chitosan in addition lowers the LDL, or the “bad” cholesterol and increases levels of HDL, or “good” cholesterol.  It does this by restricting the LDL cholesterol before it can be dispersed into the bloodstream. 

Companies selling products containing Chitosan even go as far as claiming that there is medical research proving its effectiveness.  However, none of these studies were actually found in medical research, which degrades their validity.  Three companies in particular, Grassroots Natural Products, Discover Nutrition, and Naturex assert that a scientific study in Helsinki concluded that when patients took several grams of the product with each meal over a four-week time period, that they lost percent of their total body fat.  This same study showed that LDL cholesterol levels dropped 32 percent and HDL levels increased by 7.5 percent.  However, after research through medical journals, no such trial was found.   



Benefits of Weight Loss

            With all of the poor health behaviors, the percent of obese people in the United States is increasing.  Obesity can cause the following disorders (Kaplan, Sallis, and Patterson 401):

            · Cardiovascular Disorder

            · Impaired Pulmonary Function

            · Digestive Diseases

            · Orthopedic Problems          

· Obstetric Problems                           

            · Cancer

            · Endocrine and metabolic disorders

            · Emotional and social problems     


Losing weight  can decrease a person’s chance of contracting any of these disorders.  If a person is obese, it is essential to their health to lose weight.             



Medical Studies

What does chitosan actually do?


            Chitosan, as a dietary fiber, forms “viscous solutions or gels in the stomach and small intestine [and] may also act to slow absorption and transit by increasing the viscosity of lamina contents”(Edwards 1990, 95).  Because chitosan has an NH4+ group binded to a polyglucosamine chain it has a “bile acid-binding capacity” which can lead to “reduced lipid absorption and increased faecal sterol excretion” (Razdan, A., and Pettersson, D 1996, 388).  Coinciding with claims that the companies made about their product, Chitosan has been shown to bind bile acids in vitro at low pH, and a human study did show that bile acids are excreted when chitosan is taken (Razdan, A., and Pettersson, D 1996, 395).   

Does it really control weight gain and aid in weight loss?


The Studies:


            In a 1999 double-blind, randomized, placebo controlled trial performed on 34 women and men, Chitosan did not prove effective in weight loss.  The study was advertised in the press and invited over weight people to participate in a trial of weight reduction.  The subjects had to be between the ages of  18 and 60, have a body mass index of 23.9-28.5 kg/m2 for women and 25-29.9 kg/m2 in men.  They could not have intestinal disorders, diabetes mellitus, concomitant medication and they could not be pregnant.  Subjects were given either four capsules of chitosan a day, containing 250mg deacetylated chitin bipolymer per capsule, or a placebo twice daily for 28 consecutive days.  The subjects were observed three times through out the study: at the beginning, after 14 days, and finally after 29 days.  At each visit body weight, height, and blood pressure were recorded and blood was taken to test cholesterol, triglycerides, Vitamin A,D,E, and K, and b-carotene.  In order to control the trial, the subjects were also told to try and maintain their normal diet, and to record what they were eating.  Compliance was also measured.  The results of this study showed that the data of 30 people, after four people dropped out, was not significantly different between that of the beginning of the study to that of the end of the study.  The following is a table showing the results of this trial:


Baseline chitosan/placebo

2-week assessment


4-week assessment


Weight [kg]




Body Mass Index [kg/m2]




Blood Pressure: systolic, diastolic




Total Cholesterol [mmol/l]





As shown in the table above, no weight was lost by the subjects ingesting the chitosan, and there was no significant difference of the weight fluctuation between the subjects receiving the chitosan compared to those receiving the placebo.  Similarly, there was no significant difference in the change of the Body Mass Index or the total cholesterol.  The study does suggest, however, that there may be reasons that there was no significant weight loss.  One reason was that the dosage given in the study was insignificant and when Chitosan was proven effective in animals, it was given at a dose that was 15-22 times that of the dose in the experiment.  Second, an analysis of the tablets distributed in the trial contained only 42% chitosan, which is less than 71% stated by the distributor.  Another factor that was suggested was that with an increased awareness of their diets, the subjects could have eaten more. 

            The study concluded that chitosan does not reduce body weight in overweight subjects.  However, it did suggest that other studies have shown that body weight could be reduced with chitosan when given with a hypocaloric diet  (Pitler, Abbot, Harkness and Ernst 1999).

            In another study performed with chitosan on broiler chickens, many of the effects of the products were studied including weight loss and cholesterol levels.  In this study, a total of 224 one-day-old broiler chickens were studied.  The chickens were divided into groups where one group was not fed any chitosan, one group was fed with a low, one medium, and one with a high viscosity chitin fraction in the chitosan.  Each chicken’s individual weight was recorded in the beginning, at both the 11th and 18th day of the trial.  At the end of the study no significant weight loss was recorded.  Research shows in this study also that the HDL-cholesterol did not increase like the companies claimed.  Although the ratio of the HDL-cholesterol: total cholesterol increased, researchers claim that this could be due to the decrease in total plasma cholesterol rather than an increase in the HDL cholesterol (Razdan, A., and Pettersson, D 1996).

So then the question comes up: does chitosan reduce LDL (bad) cholesterol and raise HDL (good) cholesterol like the companies claim?

            In a different double-blind, randomized, placebo controlled study, the effects of chitosan on cholesterol were revealed.  In this study, peroral microcrytalline chitosan (MCCh) or a placebo was given to 51 healthy, obese women.  This study, which lasted eight weeks, recorded each subject’s weight, and serum lipids (total LDL and HDL cholesterol, triglycerides).  These were recorded after 4 weeks, 6 weeks, and 8 weeks, and the study concluded that there was no significant difference between the serum total and the HDL cholesterol in those using the chitosan and those using the placebo.  This study also concluded that no weight reduction occurred when chitosan was used.

 (Hirvela, T., Wuolijoki, E., and Ylitalo, P 1999).


Although companies selling chitosan claim that the product is very effective and claim to have medical research about how well their product works, the medical studies show that when taken alone, chitosan has not been proven to help a person lose weight, increase their HDL cholesterol, or decrease their LDL cholesterol.  Instead, chitosan can cause unwanted gastrointestinal cramps and constipation. 

Methods for weight loss (Kaplan, Salis, and Paterson 408):

            · behavior modification

· improve eating habits- eat fewer calories at a time, and more importantly fewer calories in fat

·  increase physical activity and exercise

· gain social support







Edwards, Christine.  (1990).  Mechanisms of Action on Dietary Fibre on Small Intestinal Absorption and Motility.  New Developments in Dietary Fiber, 95-104.


Hirvela, T., Wuolijoki, E., and Ylitalo, P.  (1999).  Decrease in serum LDL cholesterol with microcrystalline chitosan.  Methods Find Experimental Pharmacology, Jun, 21 (5), 357-361.


Kaplan, Robert, Sallis, James, and Patterson, Thomas.  Health and Human Behavior.  New York: McGraw-Hill Inc., 1993.


Pittler, M., Abbot, N., Harkness, E., and Ernst, E.  (1999).  Randomized, double-blind trial of chitosan for body weight reduction.  European Journal of Clinical Nutrition, 53, 379-381.


Razdan, A., and Pettersson, D.  (1996).  Hypolipidaemic, gastrointestinal and related responses of broiler chickens to chitosans of different viscosity.  British Journal of Nutrition, 76, 387-397.




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