Chitosan and N-Acetyl-D-Glucosamine
Chitosan and N-Acetyl-D-Glucosamine (often shortened to NAG or N-acetylglucosamine) are closely related ingredients. Both come from chitin, the tough material that makes up the shells of crabs, shrimps and lobsters and the cell walls of some fungi. The easiest way to think of them is as a chain and its links: chitosan is a long chain, and NAG is one of the single building blocks that the chain is made from. Despite this family connection, they behave very differently in the body and are sold for very different reasons.
Where they come from
Chitin is a long chain made up of thousands of NAG units joined together.
- Chitosan is made by treating chitin (usually from crustacean shells) with an alkali. This strips off part of each building block (the "acetyl" group), leaving a long chain that is still too big to be digested.
- NAG is made by breaking chitin right down into its individual building blocks, either with acids or with enzymes. It can also be made by fermentation, which gives a shellfish-free version.
Both ingredients can therefore be made either from shellfish or from non-shellfish sources (such as fungi or fermentation), which matters for allergen labelling and vegan claims.
Side-by-side comparison
| Chitosan | N-Acetyl-D-Glucosamine (NAG) | |
|---|---|---|
| What it is | A long chain (a type of fibre) | A single small unit (an amino sugar) |
| Main source | Crustacean shells; also fungi | Crustacean shells; also fermentation (shellfish-free) |
| Digested and absorbed? | No – passes through the gut like fibre | Yes – absorbed into the body |
| Dissolves in water? | No (only in mildly acidic liquids) | Yes, easily |
| Taste | Fairly neutral | Mildly sweet |
| Typical uses in supplements | Weight management and cholesterol products | Joint and cartilage products; sometimes gut-health products |
| How it is thought to work | Binds fats and cholesterol in the gut so less is absorbed | Supplies a building block for cartilage, joint fluid and the gut lining |
| Authorised health claim (GB/EU) | Yes – "Chitosan contributes to the maintenance of normal blood cholesterol levels" (needs 3 g per day) | None – glucosamine joint claims have been rejected |
| Dose limits to watch | Normally used at gram levels | Keep below about 1350 mg NAG per day (see Glucosamine) |
Similarities
- Both come from the same parent material, chitin, and are usually made from crustacean shells.
- Both are built from the same type of sugar unit (glucosamine-based).
- Both can be made in shellfish-free versions, from fungi or by fermentation.
- Both are used in food supplements, usually in capsule or powder form.
- When made from shellfish, both may need allergen consideration and are not suitable for vegans or people avoiding shellfish.
Key differences
- Size: chitosan is a large chain; NAG is a single small unit. This is the root of most other differences.
- What happens in the body: chitosan is not absorbed and works inside the gut, much like a fibre. NAG is absorbed into the bloodstream and used by the body as a building block.
- Purpose: chitosan is mainly sold for cholesterol and weight management; NAG is mainly sold for joint support.
- Health claims: chitosan has an authorised cholesterol claim; NAG has no authorised health claims.
- Medicines borderline: NAG is a form of glucosamine, so the MHRA's glucosamine guidance applies – doses must stay below the level treated as medicinal (see Glucosamine). There is no equivalent limit for chitosan.
- Side effects and interactions: because chitosan binds fats in the gut, it may reduce the absorption of fat-soluble vitamins (A, D, E and K) and some medicines, so it is usually advised to take it away from other supplements and medication. NAG does not have this effect.
Regulatory notes
- Chitosan from crustacean shells has a long history of use and is not treated as a Novel Food. Chitosan extracted from fungi (such as Aspergillus niger or mushrooms) is an authorised Novel Food and must meet the conditions set out in the Union list of novel foods.
- NAG is a form of glucosamine and falls under the MHRA's 2018 guidance on glucosamine doses. Its Novel Food status depends on how it is made – check the source and production method with the supplier, particularly for fermentation-derived material.
- For any shellfish-derived material, confirm allergen status (crustaceans are one of the 14 major allergens) with the supplier specification.
In short
Chitosan and NAG are relatives from the same family, but they do different jobs. Chitosan is a large, indigestible chain that stays in the gut and is used for cholesterol and weight-management products, backed by an authorised cholesterol claim. NAG is a small, absorbable building block used for joint products, has no authorised claims, and must be kept below the MHRA glucosamine dose guidance.
See also
References
- EU Register of Nutrition and Health Claims – chitosan and blood cholesterol: https://ec.europa.eu/food/food-feed-portal/screen/health-claims/eu-register
- Commission Implementing Regulation (EU) 2017/2470 – Union list of novel foods: https://www.legislation.gov.uk/eur/2017/2470
- RxList – N-Acetyl Glucosamine: https://www.rxlist.com/n-acetyl_glucosamine/supplements.htm
- Ethical Nutrition – Vegan glucosamine vs crustacean glucosamine: https://ethical-nutrition.com/blogs/supplements/vegan-glucosamine-vs-crustacean-glucosamine
- G&G Cloud – Glucosamine (MHRA 2018 dose guidance): https://gandg.cloud/index.php?title=Glucosamine