Chitosan – promoted for weight loss, cholesterol and blood pressure?


By Prof. Raphael Nyarkotey OBU    

Chitosan is made from chitin, a fibrous compound found mainly on the hard outer skeletons of crustaceans and in the cell walls of some fungi. One study revealed that an enzymatic reaction produces chitosan — a more suitable form for supplements (Moraru et al. 2018).

Another study by Hans Merzendorfer and Ephraim Cohen(2019) shows that chitosan is biodegradable and has been used in the development of antimicrobial films for food packaging. It’s also approved for use in wound dressings due to its ability to form a gel. Chitosan is now being studied for use in medications and tissue engineering.

A previous study by Younes I. and Rinaudo M (2018) also found that commercially available chitosan is derived from crabs and other shellfish. Grandview Research reports that in 2019, the global chitosan market was valued at US$6.8billion and it’s expected to grow almost 25 percent by 2027.

Do chitosan supplements work?

Chitosan supplements are regarded as fat-blockers. This was explained in a study by Moraru et al. 2018, indicating that chitosan acts by turning into a gel in the stomach. The study further explained that when that gel moves from the stomach to the intestines, it binds to fat and cholesterol.

The study further shows that chitosan could support weight loss and lower cholesterol by removing fat and cholesterol from the body instead of allowing the body to absorb them.

Thus, it is important to take it before meals to remove the fat from the body; otherwise, there would be nothing in the gut for it to bind to. Some studies (Guerciolini et al. 2001; Gades and Stern JS. 2005) found that chitosan did not significantly increase fat excretion in stool. Though chitosan is a fibre and could form a gel in the body, there’s no indication that it traps fat.

Chitosan supplements – science

Weight loss

Moraru et al. (2018) analyzed data from 14 studies including a total of 1,101 participants with overweight or obesity. The study compared weight loss outcomes in those consuming chitosan supplements with those taking a placebo. Results showed that chitosan supplementation slightly decreased body weight and body mass index (BMI) when paired with a calorie-restricted diet and physical activity.

These results support the findings of a similar, older review, which found that chitosan supplements may be more effective than placebo as part of a short-term treatment plan for overweight and obesity (Jull et al. 2008; Moraru et al. 2018). Both reviews (Jull et al. 2008; Moraru et al. 2018) found a decrease in cholesterol levels and blood pressure.

The studies (Jull et al. 2008; Moraru et al. 2018) reported that many studies on chitosan supplements were of poor quality and that there was significant variability among results. The studies that were deemed high quality found chitosan’s impact on body weight to be less (Jull et al. 2008; Moraru et al. 2018).

The other study that was important had vitamin C to be added. This study used 3 grams of chitosan per day and found it to be more effective for weight loss when paired with 2 grams of L-ascorbic acid — a type of vitamin C (Jung et al. 2014).

Another study (Pittler MH and Ernst E. 2004) tested the evidence for chitosan, among other commonly used supplements for weight loss like garcinia cambogia and guar gum to find that there’s no convincing evidence that these supplements work to reduce body weight. Finally, another study by  Mhurchu et al. (2009) found that the effects of chitosan on body weight were minimal and “unlikely to be of clinical significance”.

Decreased cholesterol levels, blood pressure

Studies have found chitosan to have a higher effect on cholesterol levels than on weight loss. For instance, Huang et al. (2018) pooled data on cholesterol levels from more than 1,000 people and concluded that chitosan lowered both total cholesterol and LDL (bad) cholesterol.

In this study, HDL (good) cholesterol had no effect; taking chitosan may still be an effective part of a cholesterol management plan. Huang et al. (2017) explored chitosan’s effects on blood lipids and blood pressure and found that consumption of the sugar significantly decreased diastolic blood pressure at higher dosages and in shorter-term interventions, but it did not affect systolic blood pressure.

Wound healing, anticancer

Shariatinia et al. (2019) study found that chitosan-based compounds may be beneficial for wound healing. They have exhibited antimicrobial activity, fighting gram-negative and gram-positive bacteria.

Hence, chitosan topicals, such as gels and sprays, are used in wound dressing to reduce swelling and fight infections. As an anticancer agent, one study by Cheung et al (2015) found that chitosan and its derivatives exhibit anti-tumor activity. It has been shown, in both in vitro and in vivo models, to elevate the production of T-lymphocytes or white blood cells. Researchers also found that chitooligosaccharides, which are degraded products of chitosan, have proven to repress tumor growth in mice with lung cancer.

Chitosan supplements – Warning

One study by Pittler and Ernst. 2004; Baker et al. 2009 found that taking too many chitosan supplements may trigger constipation, nausea and an upset stomach.  Because chitosan is taken from crab, shellfish or mushrooms, you should avoid chitosan supplements.

Chitosan may also interfere with the absorption of fat-soluble vitamins such as vitamins A, D, E and K, as well as calcium and magnesium. Hence, do not take chitosan supplements at the same time as any other supplements. Finally, one study by Huang et al. (2007) found that Chitosan could have a negative interaction with medications like warfarin.

Dosage and safety

One study by Moraru et al. (2018) explained that the European Food Safety Authority’s Panel on Dietetic Products, Nutrition and Allergies set the maximum recommended daily intake of chitosan at 3 grams. There is currently no recommended maximum amount established in the United States.

Though studies have found chitosan supplementation to be generally safe in adults, the doses studied range widely, from 0.34–3.4 grams of chitosan per day. It is instructive that one stay at the 3-gram maximum set by European safety authorities. When looking for a supplement, always verify that it has been third-party tested. Third-party testing ensures that the supplement meets certain purity and potency standards.

Finally, look for a seal on the packaging from an organisation such as NSF InternationalUSP or ConsumerLab. These seals are typically good indicators of supplement quality.

Take home

  • Chitosan is a widely available supplement promoted for weight loss though the research is mixed.
  • Chitosan is a sugar or polysaccharide that’s obtained from the shells of crustaceans, including shrimp, crab and lobster.
  • There is some evidence that supplements made with sugar or its derivatives may reduce blood pressure, and topicals may help with wound healing.
  • There’s no clear recommended dose for chitosan, but common doses range from 500 milligrams to four grams per day.

NB: Prof. Nyarkotey has strict sourcing guidelines and relies on peer-reviewed studies, academic research institutions and medical associations to justify his write-ups. My articles are for educational purposes and do not serve as medical advice for treatment. I aim to educate the public about evidence-based scientific naturopathic therapies.

The writer is a Professor of Naturopathic Healthcare, a Medical Journalist, and a science writer. He is also President, Nyarkotey University College of Holistic Medicine & Technology (NUCHMT)/African Naturopathic Foundation, Ashaiman, Ghana.

  1. mail: [email protected]. for more.

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