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Chitosan and Glucomannan: How do these allies act in weight reduction diets?

Chitosan and Glucomannan: How do these allies act in weight reduction diets?

Published: 30 April, 2024 | 7'

In this article, we explore the role of chitosan and glucomannan, two ingredients that have multiple properties and have proven to be very useful when included as a nutritional supplement in weight loss programs.

To address this, we have the Doctor Rita Cava, biologist, dietitian nutritionist, and doctor in nutrition and food technology, with over 20 years of experience in research, teaching, and clinical practice.

Chitosan and Glucomannan, what are they used for?

Overweight and obesity have become a global health threat, being associated with a significant increase in the risk of cardiovascular diseases, diabetes, metabolic syndromes, and inflammatory problems, among others. For this reason, "losing weight, specifically body fat, significantly reduces the risks associated with a deterioration in health, always keeping in mind that it is not only about promoting weight loss, but also its maintenance and avoiding the dreaded rebound effect," explains Doctor Rita Cava.

The current clinical interventions to achieve weight reduction include caloric restriction, exercise, habit modification, and nutritional supplementation. Specifically, "within nutritional supplementation, food supplements containing chitosan and glucomannan provide notable benefits in weight control ," adds the specialist.

These benefits are recognized by the EFSA with the following health claims:

  • Chitosan contributes to maintaining normal blood cholesterol levels (EFSA).
  • Glucomannan, in conjunction with a hypocaloric diet, contributes to weight reduction and to the maintenance of normal blood cholesterol levels (EFSA).

Let's review how chitosan and glucomannan promote weight reduction.

Chitosan: beyond weight control

Chitosan, a multifunctional oligosaccharide for well-being

Chitosan is an oligosaccharide (polyglucosamine) derived from the polysaccharide chitin, the second most abundant after cellulose.

Origin and extraction process

Chitin is mainly found in the shells of crustaceans and insects, as well as in certain fungi, algae, and yeasts. It is chemically inert, highly insoluble in both water and acid.

Chitosan is extracted from chitin through a hydrolysis (or acetylation) process, which makes it more soluble in water and less viscous. It is biocompatible, non-toxic, mucoadhesive, non-allergenic, and easily absorbed along the gastrointestinal tract.

Benefits of Chitosan in metabolism

Chitosan limits fat absorption

"Once ingested, chitosan binds to fats in the intestines, limiting their absorption, which directly impacts weight reduction," explains the expert.

Other actions of chitosan include modulating the gastric hormones that control the hunger/satiety cycle and reducing the formation of adipocytes (fat cells).

Clinical studies

Several clinical studies have evaluated the use of chitosan in more than 1,200 overweight individuals, whose results have shown weight reductions of up to 2 kg, a 1 kg/m2 reduction in body mass index, and up to 1 g reduction in body fat, for at least 12 weeks2,8,10.

Chitosan's action in modulating cholesterol levels

Chitosan also acts on bile enzymes (which dissolve ingested fats), which "decreases cholesterol absorption and promotes the control of lipids in the bloodstream," explains Cava.

The reductions in cholesterol and LDL7,10 with the use of chitosan can be up to 10%, also controlling blood glucose levels7 and blood pressure10.

Glucomannan: controlling appetite

Incorporating Glucomannan into the daily diet

Glucomannan is a high-quality dietary fiber and a safe food additive.

Glucomannan is a type of soluble hemicellulose derived from the konjac plant (Amorphophallus konjac), which is not easily hydrolyzed (broken down) by stomach enzymes, so it can go directly to the colon and be used by intestinal microorganisms (microbiota).

As a soluble dietary fiber, glucomannan becomes highly viscous after absorbing water during digestion. The viscosity and purity of glucomannan fiber are quality and efficacy factors, so it is recommended that the viscosity be equal to or greater than 100,000 mPa.s.

Benefits of Glucomannan in digestive well-being

Appetite suppressant

Glucomannan is composed of carbohydrate chains (glucose and mannose), with high water absorption and expandability. One gram can absorb up to 200 ml of water. 

"Due to its water-binding capacity, konjac fiber expands in the stomach, providing a feeling of fullness and increasing the viscosity of the bolus, delaying gastric emptying and prolonging the feeling of fullness," explains the specialist.

Clinical Studies

Clinical studies have shown that the use of glucomannan reduces food intake by up to 30% due to the feeling of fullness1, which promotes weight loss of 3-4 kg/60 days4.

Furthermore, other studies confirm its positive effect on cholesterol control and blood glucose3,6,12.

Glucomannan and intestinal well-being: prebiotic effect

Although dietary fibers such as glucomannan cannot be directly digested by the gastrointestinal tract, they can be fermented by the intestinal microbiota, resulting in the production of short-chain fatty acids (SCFAs) such as acetate, propionate, and butyrate in the colon," explains Dr. Cava.

The addition of glucomannan to the diet6 promotes the growth of genera such as Bifidobacterium and Lactobacillus that produce SCFAs, maintaining metabolic and glucose balance as well as the structure of the intestinal barrier. It also has positive effects on energy expenditure, inflammation, and oxidative stress modulation.

Glucomannan in the fight against constipation

Glucomannan is a dietary fiber considered as a "bulk-forming laxative" and has beneficial effects on digestion.

As mentioned earlier, the specialist explains: "the konjac fiber absorbs water exceptionally, directly increasing stool volume and softening it, stimulating intestinal peristalsis and accelerating the defecation rate, thus reducing the likelihood of constipation".

Additionally, the prebiotic effect of glucomannan on the intestinal microbiota is also a favorable factor for improving defecation3,6.

Instructions for use of Chitosan and Glucomannan

The recommended doses by the Spanish Food Safety Agency (AESAN) are:

  • Chitosan up to 3 g/day: it is recommended to be taken three times a day, before meals, and the maximum dose should not be exceeded.
  • Glucomannan up to 4 g/day: it should be taken with at least 2 glasses of water to ensure it reaches the stomach with each main meal (three times a day). The maximum dose should not be exceeded.
  • Both can be taken simultaneously.

Taking Chitosan and Glucomannan compared to other fibers

Chitosan and Glucomannan

As the nutritionist states: "there is a variety of dietary fibers, and the majority have beneficial effects on the intestinal microbiota, body weight reduction, adiposity, food intake, and inflammation markers. However, they differ in their composition and main mode of action, so it is important to know these differences when selecting the one that best suits our objectives".

For example, let's look at the differences with respect to inulin, one of the most well-known and widely used soluble fibers in weight control diets.

All three ingredients, chitosan, glucomannan, and inulin, are useful for modulating the intestinal microbiota.

The main difference lies in their composition. While chitosan and glucomannan mainly contain glucose, inulin is composed of fructose, which is key in determining intolerances and digestive problems.

With regard to chitosan, although inulin modulates the intestinal microbiota and its metabolism, it does not have the same effect of limiting fat absorption and influencing gastric hormones in the hunger/satiety cycle that chitosan has.

Another structural difference is that inulin has very low viscosity, whereas glucomannan has a high viscosity, which is very beneficial for improving intestinal transit.

In addition to inulin, there are other food ingredients used in weight and metabolic control regimens, such as Garcinia Cambogia and chromium, as they act on thermogenesis and blood glucose control. "The decision to combine these ingredients with chitosan and glucomannan depends on medical advice and health objectives," concludes the nutritionist.

Final recommendations from Dr. Rita Cava regarding the use of chitosan and glucomannan

The main recommendation from Dr. Cava is to seek assistance from a nutritionist, "first to determine the diet that best suits individual needs, and secondly, to ensure that both chitosan and glucomannan can contribute to overall well-being. Additionally, there are some warnings regarding the use of these ingredients that should be monitored by a specialist," she explains.

If you want to learn more about nutrition and weight control...



Content prepared by the specialists of the MARNYS Scientific Information Department in collaboration with Dr. Rita Cava. This article is for informational purposes only and does not replace the consultation of a specialist.

Ruth GómezAbout the specialist

Dr. Rita Cava Roda

Dr. Rita Cava Roda, Biologist, and Ph.D. in Nutrition and Food Technology. University professor with over 20 years of experience in research and teaching, as well as a nutritionist and dietitian.

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