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CHITOSAN AND OBESITY MANAGEMENT
Mikio Kato, MD, FACS, FACOG Gene Mazzocco, MD, FACP Edward O. Dingilian, P.E.
Overweight and obesity are the most common nutritional disorders in the United States, affecting the majority of adults in the country.1 Recent reports including the latest National Health and Nutrition
Examination Survey (NHANES III) have focused attention on an alarming increase in the prevalence of obesity.2 Among all hospital discharges, the proportion of discharges with obesity-associated diseases has
increased dramatically in the past 20 years.3 Approximately 67% of adult African-American and Hispanic women are overweight or obese, compared with 46% of non-Hispanic white women.4
Body Mass Index (BMI), a formula that combines weight and height, is commonly used in epidemiological studies assessing the relationship between weight and disease. However, body weight and body composition are function of genetics, health status, basal metabolic factors, dietary intake, physical activity, stress, race, and hormonal factors. Family and adoption studies suggest that genetic factors account for an estimated 20%-40% of the variance in body weight. Body fat distribution also appears to be heritable .5
With rare exceptions, obesity is preventable. It is an ageless disease that is rising rapidly worldwide, with prevalence among children and adolescents under 19 years old. With increased longevity, rapid rise in obesity is expected to lead to increased rates of cardiovascular diseases, Type 2 diabetes, certain cancers, gallbladder disease, and osteoarthritis, with severe near future implications on health providers, world population and worldwide economies.
Obesity results from sustained imbalance between dietary energy intake and expenditure. Throughout evolution, humans evolved promoting accumulation of fat during periods of feast to survive periods of famine. However, what was an asset during evolution has become a liability in present times with abrupt changes in which high-fat foods are readily available, and an environment where there is little need for physical activity. Also, over the millenniums the composition of the human diet has changed with greater emphasis to fat filled foods for more flavor, taste, and satiety. Fat foods give the feel of fullness and satisfaction.
The human body draws its energy needs from dietary intake of carbohydrates, proteins and fats. Carbohydrates are usually the main source of dietary calories, yet the body stores of glycogen are very limited .6 Proteins intake is usually about 15% of daily calories, and amounts to little over 1% of the total protein stores.7 Body fat stores are large, and fat intake has no influence on fat oxidation to calorie needs. The entire excess fat intake is stored as body fat, which is denser and provides twice the energy compared to carbohydrates and proteins. The body oxidizes fat after exhausting the dietary carbohydrate and protein. Negative energy balance is the only driving force for fat oxidation.
For a 150lbs man with 20% body fat, the fat store represents 123000 kcal in comparison to his need of 2500 kcal/day of which on the average the fat represents 875 kcal. For an intake less than 2500 kcal/day, the body draws the deficit energy needs from stored fat. For a diet over 2500 kcal/day, the unused portion is converted and stored as fat, which on continued basis results to gradual weight gain.
In most cases body weight loss results from combination of reduced calorie intake and increased physical activity. Many studies demonstrate that obese adults can lose about 0.5kg per week by decreasing their daily intake to 500 kcal to 1000 kcal below the calorie intake required for the maintenance of their current weight. More severe calorie restrictions with the use of diets that are low in calories, increase the rapidity of weight loss, but not the rate of long-term success in maintaining a reduced weight.1 Treatment selection should be guided not only by the individual’s BMI and health risks, but also by the patient’s history of weight loss efforts.8 Treatment options must be selected with consideration of their safety, efficacy, and cost after consulting with the physician.
Anti-obesity prescription medications currently approved for weight loss in the United States fall into two broad categories: those that decrease food intake by reducing appetite or increasing satiety (appetite suppressants), and those that decrease nutrient absorption called statins. The only FDA-approved medication for obesity that reduces nutrient absorption is orlistat (Xenical). Side effects of orlistat include flatulence with discharge, fecal urgency, fecal incontinence, oily spotting, and increased frequency of defecation.1 The safety and efficacy of weight loss medications beyond two years of use have not been established. In addition, although some risk factors for obesity related disease are improved with the use of weight-loss medications, the long-term effect of such medications on morbidity and mortality has not been determined.1
Overweight and obese individuals have also access to a variety of dietary supplements that may show with certain individuals some degree of body weight loss under specific conditions. A dietary supplement product currently sold for weight management is chitosan. Overweight and obese individuals report from no loss to significant weight loss after using chitosan.
Chitosan is the generic name of a large family of long chain biopolymers derived from natural chitin found in the shell of shrimp, crab and lobster. The active ingredient in chitosan is glucosamine that has unique properties when used as dietary supplement. Chitosan dissolves in stomach acid, becomes electrically charged, thereby binding to opposite charged particles like digested fat, and then precipitates together with bound fat in the alkaline medium representative of the small intestine. In-vitro, affinity of chitosan to bind fats, oils, and grease is well documented in scientific literature.9
Based upon laboratory demonstrated fat binding affinity of chitosan, the dietary supplement market extended the same hypothesis with the intent to bind, and partially or totally eliminate dietary fat from the gastro-intestinal tract prior it being absorbed by the body. The actual binding mechanism by chitosan in the gastro-intestinal tract in the presence of other nutrients, enzymes, electrolytes, body metabolism is complex and presently little understood.
From human and animal tests results, it is postulated chitosan dissolves in the stomach to form an emulsion which binds with digested fats, and precipitates in the alkaline part of the intestine. A great portion of these bound fats are excreted in the feces rather than being absorbed. Animal tests show chitosan might also inhibit intestinal absorption of dietary fat by inhibiting hydrolysis of fat by the pancreatic enzyme lipase.10 Chitosan appears to be devoid of side effects in daily doses averaging 1500 mg-2500 mg . The absence of chitosan standards for dietary supplement applications may be a partial explanation consumers are experiencing varying results. It is recommended to purchase chitosan supplements from established manufacturers who can back their products with verifiable certificates of analysis.
For certain overweight or mildly obese individuals with hypercaloric diet in fat, chitosan of specific chemistry, purity and dosage combined with physical exercise on sustained basis may be helpful to manage their body weight. Individuals with shellfish allergies, pregnant, lactating women, are recommended not to use chitosan. Individuals of 14 years of age or less, persons on medication are asked to consult their physician prior to using chitosan. Individuals using chitosan for weight management should supplement their daily diet with oil soluble vitamins A, D, E, K.
Moderating calorie intake, limiting saturated fats, increasing intake of soluble fiber, fresh fruits, vegetables, physical activity coupled with reduced stress are still the best proven choices for sustained body weight management.
1. Yanovski S.Z., Ph.D. et al: Obesity. N Engl J Med, 2002; vol 346: 591-602
2. Glazer, G., Ph.D.: Long-term Pharmacotherapy of Obesity. Arch Intern Med., 2001; vol 161, No. 15
3. Dietz, W.H., MD, Ph.D. et al: Economic Burden of Obesity in Youths Aged 6 to 17
years. Pediatrics, 2002; vol 109, No. 15
4. Popkin, B.M., Ph.D.: The Nutrition Transition in Low-income Countries.
An Emerging Crisis. Nutrition Review, 1994; vol 52, 285-298
5. Bouchard, C., Ph.D.: Genetic Influence on Body weight and shape
Eating Disorders and Obesity, pp 21-26
6. Acheson, K.J. Ph.D. et al: Glycogen Storage Capacity and de novo Lipogenesis
During Massive Carbohydrate Overfeeding in Man. Amer J Clin Nutrition, 1998; vol 48, 240-247
7. Bray, G.A., Ph.D.: Treatment for Obesity: A Nutrient balance/nutrient partition
Approach. Nutrition Review, 1991; vol 49, 33-45
8. Womble, L.G., Ph.D. et al: Commercial and self-help Weight Loss Programs.
Handbook of Obesity Treatment, 2002, pp 395-415
9. Nauss et al: The Binding of Micellar Lipids to Chitosan. Lipids; 1983, 714-719
10. Han LK et al: Reduction in Fat Storage During Chitin-Chitosan Treatment in Mice
Fed High-Fat Diet. Int J Obesity 1999; vol 23: 174-179
Mikio Kato, MD, FACS, FACOG Gene Mazzocco, MD, FACP
Edward O. Dingilian, PE, President, United Chitotechnologies, Inc., USA
Correspondence to: Edward O. Dingilian, PE