What is it?
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 sulphate and glucosamine hydrochloride; instead of a sulphur 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 sulphate 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 sulphate and glucosamine hydrochloride, which are
both absorbed extremely well.10 11 Furthermore, unlike glucosamine
sulphate, there have been no human clinical studies utilizing NAG to treat arthritis or other
health problems.
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.