Glucosamine and chondroitin
Also called: glucosamine sulfate, glucosamine hydrochloride, glucosamine HCl, chondroitin sulfate.
A duo for knee osteoarthritis whose results depend on the salt, the quality of the product and the funding of the trials.
What it is
Glucosamine and chondroitin are constituents of cartilage. As supplements, glucosamine comes from crustacean shells (crab, krill, lobster, shrimp) or from fungal fermentation, and chondroitin from bovine, porcine or poultry cartilage. People buy them for osteoarthritis, mostly of the knee.
What the label does not say
- Sulfate or hydrochloride is not a detail. Health Canada gives glucosamine sulfate the claim "helps to relieve joint pain associated with osteoarthritis" at 1,500 mg per day, but gives the hydrochloride, at 1,500 to 2,000 mg, only "helps to maintain cartilage and joint health". A European position statement (ESCEO, 2019, cited by the NCCIH) points the same way: prescription crystalline sulfate recommended, other formulations advised against.
- The GAIT trial (NEJM, 2006, 1,583 patients): neither glucosamine (hydrochloride), nor chondroitin, nor the two together did better than placebo on pain in the group as a whole, where 60.1% of patients already responded to placebo. Only an exploratory analysis of the subgroup with moderate to severe pain favoured the combination (79.2% versus 54.3%).
- Funding weighs on the results: the Cochrane review on chondroitin notes that several trials were funded by manufacturers and that the benefit becomes uncertain without them; for glucosamine, the analysis restricted to trials with well-concealed allocation no longer shows a benefit on pain.
- The guidelines contradict each other: the ACR and the Arthritis Foundation (2019) strongly recommend against using glucosamine, alone or with chondroitin, for the knee, but conditionally recommend chondroitin for the hand, where a 6-month trial (162 participants) reports less pain.
The forms on the shelf
- Glucosamine sulfate (with potassium or sodium chloride): the form used in the European trials, at 1,500 mg per day in the Canadian monograph. In the Cochrane review (25 trials, 4,963 patients), only the trials of one European pharmaceutical preparation show an effect on pain; the other preparations do not reach statistical significance.
- Chondroitin sulfate: 800 to 1,200 mg per day according to Health Canada, for at least 3 months. The Cochrane review (43 trials) credits it with 8 fewer pain points out of 100 in the short term, on low-quality data.
- Combinations with MSM, turmeric, collagen or hyaluronic acid: each ingredient is read against its own range in the Canadian monograph.
Published reference values
- Glucosamine: 1,500 mg of glucosamine sulfate per day according to Health Canada, "use for at least 4 weeks to see beneficial effects".
- Chondroitin: 800 to 1,200 mg per day, "for at least 3 months".
- Cartilage structure: two 2-year trials contradict each other. The Australian trial (605 participants, sulfate) reports less joint space narrowing with the combination only; the American trial (572 participants, hydrochloride), no difference. Cochrane reports 0.18 mm less narrowing with chondroitin.
When
The time of day does not matter; what counts is how long to wait before judging: at least 4 weeks for glucosamine and at least 3 months for chondroitin according to the Canadian monographs, and the trials retained by Cochrane last from 1 month to 3 years.
Keep apart from
- Warfarin: the NCCIH reports an increased risk of bleeding with glucosamine and chondroitin. This is a matter of monitoring anticoagulation, not of spacing doses by the hour.
To mention to a professional
- Use of warfarin or another anticoagulant, diabetes or monitored blood sugar, shellfish allergy (glucosamine often comes from their shells), pregnancy and breastfeeding (little data according to the NCCIH): check with a health care professional.
What it is sold for, and what the data show
Sold to "rebuild" cartilage and relieve osteoarthritis. The best results come from European pharmaceutical preparations of glucosamine sulfate, often in trials funded by the manufacturer; the large American trial found nothing in the group as a whole, and the data on cartilage structure contradict each other. For chondroitin, the effect is modest and of low quality. Nothing shows that a capsule rebuilds cartilage.
Sources
- NCCIH, Glucosamine and Chondroitin for Osteoarthritis
- Clegg et al., Glucosamine, chondroitin sulfate, and the two in combination for painful knee osteoarthritis (GAIT), New England Journal of Medicine (2006)
- Cochrane, Towheed et al., Glucosamine therapy for treating osteoarthritis (2005)
- Cochrane, Singh et al., Chondroitin for osteoarthritis (2015)
- Health Canada, natural health product monograph, Glucosamine Sulfate
- Health Canada, natural health product monograph, Chondroitin Sulfate
- Health Canada, product monograph, Joint Health Products, Multiple Ingredient
Educational information, drawn from the sources above. It does not replace the advice of a health professional, who remains the reference for your situation, your medications, pregnancy or breastfeeding.