Dietary Supplement N-Acetyl GlucosamineN-A-G, N-acetyl glucosamine, is an amino sugar (a building block of mucopolysaccharides). It is formed from L-glutamine and glucose. N-A-G forms the basis of complex molecular structures which are key parts of the connective tissues and mucous membranes of the body - tendons, ligaments, cartilage, bone matrix, skin, joint fluid and intestinal lining.