The human pharmacokinetics of oral ingestion of glucosamine and chondroitin sulfate taken separately or in combination

Jackson CG, Plaas AH, Sandy JD, Hua C, Kim-Rolands S, Barnhill JG, Harris CL, Clegg DO · Osteoarthritis and Cartilage

Reaches the opposite conclusion to Volpi's studies. Circulating chondroitin sulfate in human plasma sits at about 20 ug/mL, and those endogenous levels were not detectably altered by ingestion — no absorption of intact chondroitin sulfate was demonstrated. The authors note any effect would therefore have to come from breakdown products rather than the polysaccharide itself.

Population

Healthy volunteers, glucosamine and chondroitin sulfate given separately and in combination

Intervention

Oral glucosamine and chondroitin sulfate, alone and combined

Comparator

Within-subject baseline

Limitations

Pharmacokinetics with no clinical endpoint. The disagreement with Volpi turns on analytical method and on the difficulty of separating exogenous from a large endogenous pool — a null here is a failure to detect, not proof of non-absorption. Clegg is the GAIT investigator, so this group is independent of the chondroitin manufacturers.