N-Acetyl-Glucosamine

What does it do?

N-acetyl-glucosamine (NAG) is a form of glucosamine, one of the building blocks of joint tissue and other connective tissues. NAG differs from glucosamine sulfate and glucosamine hydrochloride; instead of a sulfur or chloride molecule, NAG has a larger, more complex molecule attached to it. As a result, NAG is an entirely different molecule than either glucosamine sulfate or hydrochloride, and it also appears to be handled by the body differently.

Over the years, numerous researchers have repeatedly demonstrated in animal and test tube studies that NAG is inferior to other forms of glucosamine in terms of absorption and utilization.1 2 3 4 5 6 7 However, an animal study demonstrated that NAG was able to enhance the manufacture of cartilage in damaged joints.8 A recent human study compared the absorption of NAG to a long chain of NAG molecules (POLY-Nag).9 Results showed that orally ingested NAG and POLY-Nag are absorbed and increase the blood levels of NAG, with both forms yielding similar results. In addition, there was some conversion of both molecules to glucosamine. However, the degree of conversion still resulted in lower levels of blood glucosamine levels compared to glucosamine sulfate and glucosamine hydrochloride, which are both absorbed extremely well.10 11 Furthermore, unlike glucosamine sulfate, there have been no human clinical studies utilizing NAG to treat arthritis or other health problems.

Where is it found?

NAG is available primarily in tablets and capsules.

Who is likely to be deficient?

As NAG is not an essential nutrient, no deficiency states have been reported.

How much is usually taken?

Most manufacturers recommend supplementation with 1,500 mg daily.

Are there any side effects or interactions?

No significant side effects or interactions have yet been reported in studies on NAG.

At the time of writing, there were no well-known drug interactions with N-acetyl-glucosamine.

References

1. Karzel K, Domenjoz R. Effect of hexosamine derivatives and uronic acid derivatives on glycosaminoglycan metabolism of fibroblast cultures. Pharmacology 1971;5:337–45.

2. Capps JC, Shetlar MR, Bradford RH. Hexosamine metabolism. I. The absorption and metabolism, in vivo of orally administered D-glucosamine and N-acetyl-D-glucosamine in the rat. Biochim Biophys Acta 1966;127:194–204.

3. Capps JC, Shetlar MR, Bradford RH. Hexosamine metabolism. II. Effect of insulin and phlorizin on the absorption and metabolism, in vivo, of D-glucosamine and N-acetyl-glucosamine in the rat. Biochim Biophys Acta 1966;127:205–12.

4. Richmond JE. Studies on the metabolism of plasma glycoproteins. Biochemistry 1963;2:676–83.

5. Kohn P, Winzler RJ, Hoffman RC. Metabolism of D-glucosamine and N-acetyl-D-glucosamine in the intact rat. J Biol Chem 1962;237:304–8.

6. McGarrahan JF, Maley F: Hexosamine metabolism. I. The metabolism in vivo and in vitro of D-glucosamine-1-C14 and N-acetyl-D-glucosamine-1-C14 in rat liver. J Biol Chem 1962;237:2458–65.

7. Tesoriere G, Dones F, Magistro D, Castagnetta L. Intestinal absorption of glucosamine and N-acetylglucosamine. Experientia 1972;28:770–1.

8. Grevenstein J, Michiels I, Arens-Corell M, Stofft E. Cartilage changes in rats induced by papain and the influence of treatment with N-acetylglucosamine. Acta Orthop Belg 1991;57:157–61.

9. Talent JM, Gracy RW. Pilot study of oral polymeric N-acetyl-D-glucosamine as a potential treatment for patients with osteoarthritis. Clin Ther 1996;18:1184–90.

10. Setnikar I, Palumbo R, Canali S, et al. Pharmacokinetics of glucosamine in man. Arzneimittelforschung 1993;43:1109–13.

11. Setnikar I, Palumbo R, Canali S, et al. Pharmacokinetics of glucosamine in the dog and man. Arzneimittelforschung 1986;36: 729–35.