Glucosamine and Chondroitin Explained Simply

1. What Is Glucosamine and Chondroitin?

Glucosamine is a natural building block of cartilage. Chondroitin sulfate belongs to the same group of substances and is also found in cartilage. Both substances are present in the connective tissue of humans and animals. They are available as glucosamine sulfate, as glucosamine hydrochloride, as N-acetylglucosamine, and as chondroitin sulfate. Some preparations combine glucosamine and chondroitin sulfate. Collagen, hyaluronic acid, and MSM are other substances and are not part of this group.

2. Where Is It Found, and What Is It Made From?

Both substances are found in cartilage and connective tissue, in humans and animals. For dietary supplements, glucosamine is obtained from chitin. Chitin comes from the shells of crustaceans such as crabs or shrimp. Chondroitin sulfate is produced from cartilage tissue of cattle, pigs, or cartilaginous fish. It is available as tablets, capsules, or powder. Some products contain only one substance, others both together.

3. What Does Glucosamine and Chondroitin Do? What Research Shows

Knee Osteoarthritis

In knee osteoarthritis, several controlled studies (with a comparison group) found less pain and better function with glucosamine sulfate 1014172641. Chondroitin sulfate also showed improvements in controlled studies 111322. Large randomized (participants assigned by lot) studies, however, saw no clear advantage over placebo (dummy) 181921. The results depend strongly on which preparation was tested.

Joint Pain

Summaries of several studies found small to moderate pain relief with glucosamine sulfate 1216 and with chondroitin 13. Another review saw no relevant difference from placebo 3. The preparations differ and are not interchangeable. Manufacturer-supported studies showed larger effects than independent ones 312.

Cartilage and Joint Structure

In knee osteoarthritis, the joint space narrowed less with glucosamine sulfate than with placebo in two studies over three years 2642. For chondroitin, a review found similar results 13. For the combination, the results are inconsistent 2139. With chondroitin sulfate, the knee lost less cartilage volume on MRI than with placebo 31.

Tolerability and Adverse Effects

In the studies, glucosamine sulfate was similarly tolerable as placebo 23264142. According to a review, serious adverse effects occurred less often with chondroitin than with placebo 13. In individual studies, fewer adverse effects occurred with glucosamine sulfate than with ibuprofen 2733. In a small study, more participants had gastrointestinal complaints with glucosamine sulfate than with placebo 34. The studies are mostly small and short, so the evidence is weak.

Hand Osteoarthritis

In hand osteoarthritis, pain and function improved more in two retrospective observational studies when glucosamine sulfate was added to usual therapy 2944. Such observational studies are weaker than studies with placebo. All participants also had knee osteoarthritis. The evidence is low.

Hip Osteoarthritis

In hip osteoarthritis, glucosamine sulfate was not better than placebo in a two-year randomized study 2425. A review also saw no relevant benefit in knee and hip osteoarthritis 15. So far, only a single preparation has been tested. Therefore, the evidence is unclear.

Back Pain

A review found no difference in functional status with glucosamine for back pain 7. In a subanalysis, MRI changes of the vertebrae did not change differently than with placebo 35. A small trial with a mixture of glucosamine, chondroitin sulfate and manganese ascorbate could neither show nor rule out a benefit for degeneration of the lumbar spine 38. There is only a small trial with placebo, the strength of evidence is unclear.

Other Investigations

In temporomandibular joint complaints, the mouth opened wider with the combination in a small study than with tramadol 39. In temporomandibular joint osteoarthritis, glucosamine sulfate was not better than placebo 34, but relieved pain similarly to or more than ibuprofen 3336. One study reported increased intraocular pressure 30, another found no difference 37. N-acetylglucosamine has so far only been studied in healthy people; studies in osteoarthritis are still pending 3240.

4. How Was Glucosamine and Chondroitin Taken in the Studies?

In the studies, the substances were mostly tested for oral use. They are available as tablets, capsules, or powder. Glucosamine sulfate, glucosamine hydrochloride, chondroitin sulfate, and N-acetylglucosamine were tested. Most participants took them as a single substance or as a combination. In one study, glucosamine sulfate was also injected into the muscle 28. The combination of glucosamine and chondroitin sulfate was compared with placebo or celecoxib in large studies 18192021.

5. Is Glucosamine and Chondroitin Safe? Side Effects in the Studies

Glucosamine sulfate, glucosamine hydrochloride, and chondroitin sulfate are different preparations. They cannot be exchanged for one another. Results for one form do not automatically apply to another. The studies are often small or short. For some results, the evidence is low. Manufacturer-funded studies showed larger effects than independent ones 312. Results of a combination apply only to that combination, not to the individual substance. One study reported increased intraocular pressure, especially in older adults 30.

All details with tables and sources: full expert page on Glucosamine and Chondroitin