Glucosamine vs Chondroitin: What's the Difference? Do You Need Both?

Glucosamine and chondroitin are different molecules from the same tissue. Glucosamine is a small amino sugar the body uses as a building block; chondroitin sulphate is one of the long sugar chains it builds, the part of cartilage that holds water. Both are taken for knee osteoarthritis pain, usually at 1,500 mg of glucosamine sulphate and 800 to 1,200 mg of chondroitin a day, and the trials found a small average effect for each, clearest for a prescription-grade glucosamine sulphate and for pharmaceutical-grade chondroitin, with no reliable extra benefit from taking the two together.^{1, 2, 3} The practical difference is origin: glucosamine comes from shellfish shells or, for vegan products, plant or microbial sources; chondroitin is extracted from animal cartilage, so most of it is not vegan. Neither has an authorised health claim in Great Britain.

• Glucosamine: an amino sugar; 1,500 mg of the sulphate a day in the positive trials; shellfish or vegan
• Chondroitin: a glycosaminoglycan; 800 to 1,200 mg a day in trials; made from cattle, pig or shark cartilage
• Together: no reliable advantage over either alone; warfarin is the caution for both

What is glucosamine, and what does it do?

Glucosamine is glucose with an amino group attached. Cartilage cells use it to build glycosaminoglycans, the long sugar chains that hold water inside cartilage. As a supplement it is sold as two salts, sulphate and hydrochloride, almost all of it made from chitin in prawn, crab and lobster shells; vegan glucosamine is made without shellfish, and the molecule is the same. "Rebuilds cartilage", the phrase that sells it, is not something any trial has shown; what the long trials measured was the gap between the bones on X-ray, which narrowed more slowly on a prescription glucosamine sulphate over three years.² The Wellgard joint health guide covers every glucosamine trial.

What is chondroitin, and what is it made from?

Chondroitin sulphate is a glycosaminoglycan: a chain of repeating sugar units carrying sulphate groups, whose negative charges attract the water that lets cartilage absorb load. The body makes its own; supplement chondroitin is extracted from animal cartilage, usually cattle or pig, sometimes shark. The pharmaceutical-grade chondroitin in the European trials is purified to a defined chain length; supplement-grade chondroitin varies. It is a large molecule, mostly broken down in the gut: within the American GAIT trial, swallowing it did not change the chondroitin already circulating in the blood, so if it helps, it probably does so indirectly.⁴

Glucosamine vs chondroitin: what the trials found for each

For glucosamine, the 2010 network meta-analysis of the ten largest trials, 3,803 people with knee or hip osteoarthritis, found an average effect on pain too small for most patients to notice, while the Cochrane review found that glucosamine sulphate, in the prescription preparation most of the positive trials used at 1,500 mg a day, improved pain and function against placebo, and individual response varies more than either average suggests.^{1, 2} In the UK, glucosamine sulphate was a licensed medicine for knee osteoarthritis; UK guidance does not recommend it on the NHS and GPs no longer prescribe it.⁵

For chondroitin, the 2015 Cochrane review of 43 trials in 9,110 people found pain about 10 points lower on a 100-point scale than placebo in trials under six months, judged clinically meaningful but of low certainty because most trials were manufacturer-funded; the structural evidence was mixed.⁶ The strongest single result is a six-month trial of pharmaceutical-grade chondroitin at 800 mg a day in 604 people, where it reduced pain as much as a prescription anti-inflammatory and more than placebo; the American trial of chondroitin alone at 1,200 mg found no significant effect.^{3, 7}

Do glucosamine and chondroitin work better together? What GAIT, LEGS and MOVES found

Not reliably. In GAIT (2006, 1,583 people, six months) the combination was no better than placebo overall, and an exploratory subgroup result in the 354 people with moderate-to-severe pain was not confirmed at two years.^{3, 8} In LEGS (2015, 605 people, two years) pain fell equally in every group; the combination slowed joint-space narrowing by 0.10 mm and the single agents did not.⁹ In MOVES (2016, 606 people, six months) the combination was tested against a prescription anti-inflammatory with no placebo group; pain fell by about half in both arms and it was judged non-inferior.¹⁰ Since taking chondroitin alongside glucosamine also lowered the glucosamine reaching the blood, the case for "perfect partners" is thin.⁴ Nor is "glucosamine for the pain, chondroitin to stop the decay" what the trials show: both have symptom and X-ray data, neither has shown cartilage regrowth.

Is glucosamine better than chondroitin, and who might choose which?

No trial has compared the two head to head, and the pooled analyses put their pain effects within a few millimetres of each other on a 100 mm scale.¹ The evidence differs in shape: glucosamine's best results come from three-year trials of one prescription sulphate, chondroitin's from six-month trials of one pharmaceutical-grade product, and in both cases the manufacturer ran the positive trials and the independent American trial was null. Someone who wants the longest trial record chooses glucosamine sulphate at 1,500 mg of the salt, or a vegan sulphate delivering a similar amount of glucosamine; someone who has given glucosamine three months without change has a reason to try pharmaceutical-grade chondroitin at 800 mg; someone vegan, vegetarian or shellfish-allergic chooses a vegan glucosamine. Whichever you choose, read the per-serving line: the trial doses refer to the salt, potassium-chloride glucosamine sulphate is 59% glucosamine, and combination products often cut each ingredient to 500 mg to fit both into a capsule. The fair test is the same for either: three months at the trial dose, pain and morning stiffness scored before and after, stop if nothing has moved, with exercise and weight, which the NHS puts first, in place throughout.⁵ What is the best joint supplement sets both beside collagen, turmeric and omega-3 at their trial doses.

Is glucosamine chondroitin safe?

In the trials, side effects were no more common than placebo for glucosamine and serious adverse events were rarer than placebo for chondroitin; mild stomach upset is the usual complaint.^{2, 6} One interaction belongs to both: more than 40 reports to medicines agencies describe a raised INR after starting glucosamine, with or without chondroitin, in people on warfarin, usually settling once it was stopped, and the European food safety authority advised that people on coumarin anticoagulants should not take glucosamine without medical advice.¹¹ Tell your GP or anticoagulant clinic before starting either. The shellfish question belongs to glucosamine alone: most is made from crustacean shells and labels warn accordingly, although the allergen is a muscle protein in the flesh and fifteen people with proven prawn allergy took shell-derived glucosamine under double-blind challenge without reacting.¹² Why is glucosamine bad for you covers blood sugar, kidneys and pregnancy.

Is there a vegan chondroitin?

Rarely. Vegan joint supplements replace animal chondroitin with a plant-derived chondroitin alternative, usually seaweed polysaccharides with sodium hyaluronate, a different substance with no chondroitin trial record of its own. Wellgard Ultimate Vegan Glucosamine+ supplies about 1,100 mg of glucosamine as a vegan glucosamine sulphate per three capsules, close to the glucosamine the positive sulphate trials delivered, with a plant-derived chondroitin alternative made from seaweed and sodium hyaluronate in place of animal chondroitin; glucosamine has no authorised health claim in Great Britain, so what the trials found is reported on this page as evidence, and because the seaweed includes bladderwrack, which can be high in iodine, anyone with a thyroid condition should check with their GP first. Is there a vegan glucosamine explains how shellfish-free glucosamine is made and how to read its label.

Frequently asked questions

Can you take glucosamine, chondroitin and collagen together?

Yes. There is no interaction between a sugar, a sugar chain and a protein; the warfarin caution stays with glucosamine and chondroitin. Can I take collagen and glucosamine together sets out what the trials found for each.

How long does glucosamine chondroitin take to work?

Three months. The trials assessed response at three and six months and saw nothing in the first fortnight; score pain and stiffness before you start and at twelve weeks, and stop if nothing has moved.³

What is the best time to take glucosamine and chondroitin?

With a meal, at whatever time you will remember; food reduces the stomach upset some people get, and consistency over months matters more than the hour.

Sources

1. Wandel S, et al. Effects of glucosamine, chondroitin, or placebo in patients with osteoarthritis of hip or knee: network meta-analysis. BMJ, 2010. PubMed 20847017.
2. Towheed TE, et al. Glucosamine therapy for treating osteoarthritis. Cochrane Database of Systematic Reviews, 2005. PubMed 15846645.
3. Clegg DO, et al. Glucosamine, chondroitin sulfate, and the two in combination for painful knee osteoarthritis (GAIT). New England Journal of Medicine, 2006. PubMed 16495392.
4. Jackson CG, et al. Human pharmacokinetics of oral glucosamine and chondroitin sulfate taken separately or in combination. Osteoarthritis and Cartilage, 2010. PubMed 19912983.
5. NHS. Osteoarthritis: treatment and support. nhs.uk/conditions/osteoarthritis/treatment.
6. Singh JA, et al. Chondroitin for osteoarthritis. Cochrane Database of Systematic Reviews, 2015. PubMed 25629804.
7. Reginster JY, et al. Pharmaceutical-grade chondroitin sulfate is as effective as celecoxib and superior to placebo in symptomatic knee osteoarthritis (CONCEPT). Annals of the Rheumatic Diseases, 2017. PubMed 28533290.
8. Sawitzke AD, et al. Glucosamine, chondroitin sulphate, their combination, celecoxib or placebo for knee osteoarthritis: 2-year results from GAIT. Annals of the Rheumatic Diseases, 2010. PubMed 20525840.
9. Fransen M, et al. Glucosamine and chondroitin for knee osteoarthritis (LEGS). Annals of the Rheumatic Diseases, 2015. PubMed 24395557.
10. Hochberg MC, et al. Combined chondroitin sulfate and glucosamine for painful knee osteoarthritis versus celecoxib (MOVES). Annals of the Rheumatic Diseases, 2016. PubMed 25589511.
11. EFSA NDA Panel. Statement on the safety of glucosamine for patients receiving coumarin anticoagulants. EFSA Journal, 2011. PubMed 42015979.
12. Villacis J, et al. Do shrimp-allergic individuals tolerate shrimp-derived glucosamine? Clinical and Experimental Allergy, 2006. PubMed 17083356.

This article is general information, not medical advice. Joint pain with swelling, heat or redness, or pain after an injury, needs a GP, not a supplement; if you take warfarin or another anticoagulant, or have a shellfish allergy or a thyroid condition, ask your pharmacist or GP before starting glucosamine or chondroitin.