Chitosan: Everything You Need to Know

Medically reviewed by Allison Herries, RDN

Chitosan is a polysaccharide derived from chitin, an abundant substance found in the exoskeleton of crustaceans (a type of shellfish) and insects, and in the cell walls of certain fungi.

Chitosan is widely popular, with the global market value surpassing $6 billion in 2019. This is because it has been used in water treatment agents and in the pharmaceutical, biomedical, cosmetic, and food industries.

But while chitosan is also believed to offer health benefits, research results regarding its efficacy appear mixed. It's most commonly used for weight loss, high blood pressure, high blood sugar, and dyslipidemia.

This article will provide in-depth information on chitosan, including what it is and how it works. The article will also discuss the potential uses, safety risks, dosage, drug interactions, and sources of chitosan in foods and supplements.

What Is Chitosan, and How Does It Work?

After cellulose, chitin is the second most abundant polysaccharide in the world. Polysaccharides are complex carbohydrates that may include dietary fiber.

Chitin provides structure to the exoskeletons of crustaceans (e.g., lobster, shrimp, crab), certain insects, and fungi cell walls. Chitosan results from a chemical reaction in which chitin is broken down.

Aside from dietary supplements, chitosan is also used in the pharmaceutical, biomedical, cosmetic, and food industries. Various aspects of chitosan, such as its solubility and viscosity, make it of special interest to these industries.

When consumed, chitosan reacts with the acidic environment in your stomach to form a gel. This gel is thought to bond with fatty compounds and block them from absorption in the gastrointestinal tract. Ultimately, the mixture of chitosan and fat is excreted through feces.

This process may benefit those with certain health conditions, which will be explored next.

Potential Uses of Chitosan Supplements

Explainer

Supplement use should be individualized and vetted by a healthcare professional, such as a registered dietitian, pharmacist, or healthcare provider. No supplement is intended to treat, cure, or prevent disease.

Through scientific research, chitosan has been found to possess antimicrobial, antioxidant, anti-inflammatory, and other properties. These biological properties may be useful for a variety of health conditions.

Studies continue to emerge as researchers learn more about the polysaccharide and its potential applications. Some of the possible uses of chitosan are outlined below.

May Decrease High Blood Sugar

Chitosan has been proposed as a complementary treatment for high blood sugar, a common symptom of both metabolic syndrome (a group of conditions that together can lead to heart disease, diabetes, and stroke) and type 2 diabetes.

Animal and laboratory studies have found a link between chitosan and improved blood sugar regulation through decreased insulin resistance (when muscle, liver, and fat cells do not respond well to insulin and cannot take up glucose from the blood, creating the need for the pancreas to make more insulin) and increased blood sugar uptake by tissues. These benefits have been tested in various clinical trials.

A meta-analysis of 10 clinical trials found somewhat conflicting results regarding the effectiveness of chitosan in lowering blood sugar. While chitosan appeared to decrease fasting blood sugar and hemoglobin A1c (HbA1c), a blood test to check the average blood sugar levels over three months, it did not have a significant effect on insulin levels.

Researchers pointed out that the best results were seen when chitosan was used at a dose of 1.6 to 3 grams (g) per day and for at least 13 weeks.

One study found that chitosan may also play a role in diabetes prevention. In the study, participants with prediabetes (when blood glucose levels are high but not high enough to be considered diabetes) were randomized to take either a placebo (a substance of no benefit) or chitosan supplement for 12 weeks. Compared to the placebo, chitosan improved inflammation, HbA1c, and blood sugar levels.

Overall, human trials on chitosan for blood sugar control are lacking in study size and design. Additional research is needed in this area.

May Decrease High Blood Pressure

A limited number of clinical trials have shown a relationship between chitosan and blood pressure. More specifically, chitosan has been found to reduce high blood pressure in some small-scale human studies. However, some research results have been mixed.

Chitosan is thought to reduce blood pressure by binding with fats and carrying them through the digestive tract to be made into feces. Increased fat excretion would lead to reduced levels of fats in the blood, a risk factor for high blood pressure.

A review of eight studies concluded that chitosan may lower blood pressure but not significantly. The best results came when chitosan was used in high doses but for shorter periods. Diastolic blood pressure (but not systolic blood pressure) decreased significantly when chitosan was taken for less than 12 weeks at doses greater than or equal to 2.4 g per day.

Although these results may appear convincing, they are not definitive proof that chitosan supplementation lowers blood pressure. More research is necessary to further explore the relationship between chitosan and blood pressure.

May Help With Weight Loss

Probably the most popular health claim of chitosan is that it may help with weight loss. While there is some evidence to support this claim, it's important to remember that using dietary supplements as a sole measure for weight loss is not recommended.

Chitosan derived from fungi was used in one clinical trial involving 96 adult participants who were classified as overweight or having obesity. Participants were given capsules that contained either a placebo or 500 mg of chitosan and were asked to take them five times per day for 90 days.

Compared to the placebo, results showed that chitosan significantly reduced body weight, body mass index (BMI), and anthropometric measurements (blood, muscle, and fat measurements) in the study participants.

In a different study, chitosan was compared to a placebo in 61 kids classified as overweight or having obesity. After 12 weeks, chitosan use resulted in decreased body weight, waist circumference, BMI, total lipids, and fasting blood sugar in the young participants. These results are thought to be due to chitosan's ability to remove fat from the digestive tract for excretion.

Despite these results, larger human trials should be conducted before chitosan can be safely recommended for weight loss.

May Promote Wound Healing

Due to its antimicrobial and structural properties, there is interest in using topical chitosan for wound healing.

Research shows that chitosan aids in the wound healing process. Chitosan has been found to have antibacterial effects, which are vital to wound healing. It has also been found to increase the rate of skin proliferation (the making of new skin).

Recently, researchers have looked at chitosan hydrogels, which contain water and can be used similarly to bandages. Chitosan hydrogels may decrease the risk of infection that can affect some wounds.

A recent trial tested a chitosan wound dressing on people with second-degree burns. The chitosan dressing decreased both pain and the time it took for the wounds to heal. Chitosan was also found to reduce incidents of wound infection.

In another small study, chitosan dressings were used on diabetic wounds and compared to another wound dressing made from nanosilver particles. The effectiveness of the chitosan dressing was found to be similar compared to the nanosilver dressing. Both dressings led to gradual healing in the diabetic wounds and also prevented infections.

Safety Risks & Side Effects

Supplements typically come with a risk of side effects, and chitosan is no exception.

At this time, very few side effects have been reported for chitosan. The most common side effects associated with chitosan affect the digestive system. These may include nausea and/or constipation. However, these were only reported in a small percentage of people.

Chitosan is generally recognized as safe (GRAS) by the Food and Drug Administration (FDA) as a food additive. However, there is concern that some chitosan supplements could contain contaminants if not properly manufactured.

It's unknown how long chitosan can safely be used. In various studies, chitosan has been safely used for up to 12 to 13 weeks.

Aside from possible side effects, chitosan may not be right for everyone.

Because one of the main sources of chitosan is crustaceans, people with a shellfish allergy should avoid using it. Anyone with a mushroom allergy should also avoid chitosan sourced from fungi.

It's recommended that people who are pregnant or breastfeeding avoid using chitosan. This is due to the lack of safety information regarding chitosan use in these populations.

More information is needed to determine the full safety profile of chitosan supplements.

Dosage: How Much Chitosan Should I Take?

Explainer

Dietary supplements are not regulated like drugs in the United States, meaning the FDA does not approve them for safety and effectiveness before products are marketed. Whenever possible, choose a supplement tested by a trusted third party, such as U.S. Pharmacopeia (USP), ConsumerLab.com, or NSF.org.

However, even if supplements are third-party tested, they are not necessarily safe for all or effective in general. Therefore, it is important to talk to your healthcare provider about any supplements you plan to take and check in about potential interactions with other supplements or medications.

Currently, there are no dosage guidelines for chitosan supplements.

In clinical trials, chitosan dosing ranged from 0.3 g per day to 3.4 g per day in adults. Chitosan was also commonly used for 12 to 13 weeks in the trials.

It's recommended that you follow dosage directions as indicated on the supplement label. You can also obtain dosage recommendations from a healthcare provider.

Interactions

Chitosan may negatively interact with certain medications, supplements, or nutrients. These interactions may block the absorption or proper use of chitosan or the medications, supplements, or nutrients it is taken with.

There is concern that chitosan interacts with medications and supplements that may have similar uses. These medications and supplements include:

• Medications or supplements that act as blood thinners

• Antiviral medications or supplements

• Medications or supplements used to treat diabetes

Chitosan may also reduce the absorption of fat-soluble vitamins. However, this was only seen in animal studies. This may occur when chitosan binds to fatty substances in the digestive tract before being absorbed into the bloodstream.

It should be noted that there isn't solid evidence or clear documentation of these or other interactions for chitosan. However, it's best to be cautious and talk with a healthcare provider before using chitosan to discuss potential interactions, especially if you use any medications or supplements.

It is also important to carefully read the ingredients list and nutrition facts panel of a supplement to know which ingredients and how much of each ingredient is included. Please review supplement labels with a healthcare provider to discuss any potential interactions with foods, other supplements, and medications. 

Sources of Chitosan & Where to Look

Various foods and supplements contain chitosan. Compared to chitosan-containing foods, supplements may be easier to access and appear to be a more popular method for consuming the polysaccharide.

Food Sources of Chitosan

The main food sources of chitosan include crustaceans and certain types of mushrooms. Chitosan may also come from the exoskeleton of insects.

In crustaceans and mushrooms, chitosan is found in its original form of chitin (recall that chitosan is a derivative of chitin). Specifically, chitin is a part of the exoskeleton of crustaceans and the cell walls of some mushrooms and other fungi.

The only way to consume chitin that comes from crustaceans is through dietary supplements. This is because the exoskeletons of shrimp, crabs, lobsters, and other crustaceans are not commonly eaten.

Chitin has been found in both edible and nonedible mushrooms. However, an enzymatic reaction has to occur for chitin to be converted to chitosan. Chitosan is considered to be more easily digested than chitin.

Supplements tend to be a better option for getting chitosan.

Supplement Sources of Chitosan

Due to their popularity, chitosan supplements are not difficult to find. There are a number of websites that sell chitosan supplements. You can also find chitosan supplements in certain retail stores, grocery stores, or specialty nutrition shops.

Chitosan supplements come in many forms, including capsules, powders, and tablets. There are also topical chitosan options, like gels.

Some chitosan supplements may be mixed with other nutrients, herbs, or ingredients. Be sure to read the full list of ingredients to understand the product you purchase.

Many chitosan supplements are sourced from crustaceans. If you are vegan or vegetarian, look for chitosan that has been sourced from mushrooms instead.

Of course, you shouldn't use chitosan products if you're allergic to any of the ingredients. For example, if you have a shellfish allergy, then you should avoid using chitosan supplements that come from crustaceans.

Several chitosan supplements on the market can fit other diets, like a gluten-free diet or an organic diet. This information should be listed on the label or packaging of the supplement.

Summary

Chitosan is a derivative of chitin, a polysaccharide present in the exoskeletons of crustaceans, certain insects, and the cell walls of fungi.

Chitosan contains nutrients and bioactive compounds that may be useful for high blood sugar, high blood pressure, wounds, and other conditions. In general, more research is needed on chitosan to prove its benefits.

Side effects are possible when taking chitosan, so talk with a healthcare provider to make sure it's the right supplement choice for you.

Frequently Asked Questions

Who should not take chitosan?

Some people should avoid using chitosan.

Some chitosan products contain common allergens, like shellfish. Other chitosan products are made from mushrooms. Avoid using chitosan if you're allergic to shellfish, mushrooms, or any other substance in the ingredients list.

You should talk with a healthcare provider about using chitosan if you're pregnant or breastfeeding. There isn't much research on the use of chitosan in these populations, so it may be best to avoid it.

How can I get chitosan naturally?

To get chitosan naturally, you'd need to eat foods that contain chitin. Chitin-containing foods include mushrooms and crustaceans. However, chitin is only available in the exoskeletons of crustaceans, a part of the animal that isn't typically eaten.

Chitosan is most commonly found in supplements. This is because a chemical reaction is needed to transform chitin from foods into chitosan.

Can I take chitosan daily?

When using chitosan supplements, you can take them daily. However, little is known about the safety of using chitosan for more than 12 weeks. Therefore, it might not be safe to take chitosan for more than 12 weeks.

Talk with a healthcare provider about the proper way to use chitosan supplements.

Read the original article on Verywell Health.