Chondroitin sulfate

What it is

Chondroitin sulfate is a glycosaminoglycan, a long sulfated sugar chain, that is a normal constituent of cartilage. Commercial chondroitin is extracted from animal tissue, from a range of land and marine species, so its structure and sulfation pattern differ between sources. Extraction and purification methods further change its purity and composition, and mixing sources produces material whose profile is not well identified. It is sold alone and, very commonly, combined with glucosamine.

What the research says

The evidence is disputed. The 2015 Cochrane review, which rated most of the underlying trials as low quality, found a small to moderate short-term pain benefit over placebo, and rated one outcome (the proportion achieving a 20 percent pain reduction) as high-quality evidence; but the same review found those benefits uncertain once analysis was limited to trials with proper allocation concealment, large samples or no pharmaceutical funding. An independent network meta-analysis found no clinically important effect, and the GAIT trial missed its primary endpoint. Serious adverse events were actually less frequent than on placebo in Cochrane's pooled analysis, but adverse-event reporting was patchy, bleeding has been reported with warfarin, and product quality is a documented problem: chondroitin is among the most adulterated supplement ingredients.

Evidence grade: Disputed.

What goes wrong

Chondroitin taken with glucosamine features in pharmacovigilance reports of raised INR and bleeding in people on warfarin. (Source 1)

• Case report, Low certainty.
• Size: 1 index case plus 20 FDA MedWatch reports.
• Who: adults on long-term warfarin taking glucosamine-chondroitin.
• How long: weeks.
• Result: index case INR rose from 2.3 to 3.9 then 4.7 after the glucosamine-chondroitin dose was increased.
• Funding: not stated.

During this 5-year period, he had also been treating himself with the supplement glucosamine hydrochloride 500 mg-chondroitin sulfate 400 mg twice/day for arthritis.

A case series in patients with chronic liver disease concluded that review of their cases and the published literature suggests toxicity of glucosamine and chondroitin sulfate. (Source 2)

• Case series, Very low certainty.
• Size: 151 patients surveyed; 23 exposed; 2 with liver enzyme elevations.
• Who: outpatients with chronic liver disease.
• How long: up to one year of use in one case.
• Result: transaminases 4-fold to 7-fold above normal, normalising after discontinuation.
• Funding: not stated.

Review of these two patients and the cases described in the literature suggest toxicity of glucosamine and chondroitin sulfate.

Commercial chondroitin has been adulterated with a range of cheaper substances, including a detergent and water-treatment additive. (Source 3)

• Expert review, not systematic, Low certainty.
• Size: not a pooled analysis; a review of analytical quality-control findings.
• Who: commercial chondroitin raw materials and finished supplements.
• How long: not applicable.
• Result: no rates given; named adulterants include carrageenan, sodium alginate, sodium hexametaphosphate, maltodextrin and lactose.
• Funding: not stated.

Many (macro)molecules have been identified for CS adulteration, such as carrageenan, proteins and surfactants, cheaper polysaccharides, sodium alginate, propylene glycol alginate sulfate sodium, sodium hexametaphosphate commonly known with the name of Calgon and used as a detergent or water-treatment additive, maltodextrin and lactose.

Some chondroitin raw materials and supplements contain far less chondroitin than the label claims. (Source 4)

• Expert review, not systematic, Low certainty.
• Size: not stated as a count.
• Who: commercial chondroitin raw materials and dietary supplements.
• How long: not applicable.
• Result: in some cases as little as 5 to 10 percent of the claimed amount.
• Funding: not stated.

some raw material and dietary supplement products contain less than the claimed amount of CS, in some cases as little as 5–10%

The same review warns that extraction and purification differences can leave contaminants that create safety and reproducibility problems. (Source 5)

• Expert review, not systematic, Low certainty.
• Size: not applicable.
• Who: commercial chondroitin preparations.
• How long: not applicable.
• Result: no rates given.
• Funding: not stated.

different extraction and purification processes may introduce further modifications of the CS structural characteristics and properties and may lead to extracts having a variable grade of purity, limited biological effects, presence of contaminants causing problems of safety and reproducibility along with not surely identified origin

What the evidence supports

Cochrane found chondroitin gave statistically significant and clinically meaningful better pain scores than placebo in trials shorter than six months, on low-quality evidence with high risk of bias. (Source 6)

• Systematic review, Low certainty.
• Size: 43 RCTs; 4,962 on chondroitin and 4,148 controls (8 trials in this pain analysis)
• Who: adults with osteoarthritis, mostly of the knee.
• How long: trials from 1 month to 3 years; this analysis under 6 months.
• Result: Absolute risk difference 10% lower (95% CI 15% to 6% lower); NNT = 5 (95% CI 3 to 8); heterogeneity I2 = 70%.
• Funding: not stated for the review; the review notes some included trials had pharmaceutical funding.

Participants treated with chondroitin achieved statistically significantly and clinically meaningful better pain scores (0-100) in studies less than 6 months than those given placebo with an absolute risk difference of 10% lower (95% confidence interval (CI), 15% to 6% lower; number needed to treat (NNT) = 5 (95% CI, 3 to 8; n = 8 trials) (level of evidence, low; risk of bias, high)

For the proportion of people achieving a 20 percent reduction in knee pain, Cochrane rated the evidence high with low risk of bias, showing a 6 percentage point absolute difference. (Source 7)

• Systematic review, High certainty.
• Size: 2 trials, 1253 participants.
• Who: adults with knee osteoarthritis.
• How long: not stated in this analysis.
• Result: 53/100 on chondroitin versus 47/100 on placebo; absolute risk difference 6% (95% CI 1% to 11%); RR 1.12 (95% CI 1.01 to 1.24)
• Funding: not stated.

a reduction in knee pain by 20% was achieved by 53/100 in the chondroitin group versus 47/100 in the placebo group, an absolute risk difference of 6% (95% CI 1% to 11%)

The ESCEO working group holds a position, dated 2019, strongly recommending prescription chondroitin sulfate and distinguishing it from over-the-counter products. (Source 8)

• Official position, Certainty not rated.
• Size: a GRADE-based expert working group recommendation.
• Who: people with knee osteoarthritis.
• How long: long-term background therapy.
• Result: no effect size in the quoted recommendation.
• Funding: ESCEO working group; declared pharmaceutical industry relationships among authors.

The ESCEO working group gives a strong recommendation to the use of prescription chondroitin sulfate as Step 1 long-term background therapy, as an alternative to pCGS, and the prescription drug should be distinguished from low quality over-the-counter products.

What the evidence does not support

Cochrane reported that the apparent benefits of chondroitin became uncertain once analysis was restricted to trials with proper allocation concealment, large samples, or no pharmaceutical funding. (Source 9)

• Systematic review, Low certainty.
• Size: subsets of the 43 included trials.
• Who: adults with osteoarthritis.
• How long: varied.
• Result: no pooled estimate reported for these restricted analyses.
• Funding: the restriction itself concerns pharmaceutical funding.

These beneficial effects were uncertain when we limited data to studies with appropriate allocation concealment or a large study sample (> 200) or to studies without pharmaceutical funding.

A network meta-analysis of large trials found chondroitin did not reduce joint pain by a clinically important amount compared with placebo. (Source 10)

• Meta-analysis, Moderate certainty.
• Size: 10 trials in 3803 patients.
• Who: adults with osteoarthritis of the hip or knee.
• How long: trials of at least 100 patients per group.
• Result: Pain difference vs placebo -0.3 cm on a 10 cm VAS (95% credible interval -0.7 to 0.0 cm); no credible interval crossed the minimal clinically important difference.
• Funding: independent.

For none of the estimates did the 95% credible intervals cross the boundary of the minimal clinically important difference.

In the GAIT trial chondroitin sulfate alone did not significantly outperform placebo on the primary pain endpoint. (Source 11)

• Randomized trial, Moderate certainty.
• Size: 1583 patients randomised across five arms.
• Who: adults with symptomatic knee osteoarthritis.
• How long: 24 weeks.
• Result: Response rate 5.3 percentage points above placebo, P=0.17, against placebo response of 60.1 percent.
• Funding: independent (US National Institutes of Health sponsored)

the rate of response to chondroitin sulfate was 5.3 percentage points higher (P=0.17)

Where the evidence is mixed

Cochrane's pooled safety analysis found fewer serious adverse events on chondroitin than placebo, but noted adverse events were reported patchily across trials. (Source 12)

• Systematic review, Moderate certainty.
• Size: 6 trials for the serious adverse event analysis.
• Who: adults with osteoarthritis.
• How long: varied.
• Result: Peto odds ratio 0.40 (95% CI 0.19 to 0.82) for serious adverse events versus placebo.
• Funding: not stated.

Adverse events were reported in a limited fashion, with some studies providing data and others not.

A randomised crossover trial of glucosamine plus chondroitin in healthy overweight adults found lower CRP but no significant change in other inflammation or oxidative stress markers. (Source 13)

• Randomized trial, Low certainty.
• Size: 18 adults.
• Who: healthy overweight adults aged 20 to 55.
• How long: 28 days per period.
• Result: Serum CRP 23% lower than placebo (P = 0.048); no significant differences in the other biomarkers.
• Funding: US National Cancer Institute grant; supplements donated by Nutramax Laboratories Consumer Care, Inc.

Serum CRP concentrations were 23% lower after glucosamine and chondroitin compared to placebo (P = 0.048). There were no significant differences in other biomarkers.

Where the research disagrees

Whether chondroitin meaningfully relieves osteoarthritis pain

• Cochrane review authors (2015), systematic review of 43 randomised trials, most rated low quality: A review of randomized trials of mostly low quality reveals that chondroitin (alone or in combination with glucosamine) was better than placebo in improving pain in participants with osteoarthritis in short-term studies. (Source 14)
• Wandel and colleagues, BMJ (2010), network meta-analysis restricted to large trials: Compared with placebo, glucosamine, chondroitin, and their combination do not reduce joint pain or have an impact on narrowing of joint space. (Source 15)
• ESCEO working group (2019), expert working group position using GRADE: The ESCEO working group gives a strong recommendation to the use of prescription chondroitin sulfate as Step 1 long-term background therapy, as an alternative to pCGS, and the prescription drug should be distinguished from low quality over-the-counter products. (Source 8)

How much

• Reference intake: No reference intake (RDA or AI) exists for chondroitin. It is a glycosaminoglycan normally present in cartilage and is sold as a supplement, not classed as an essential nutrient by any body we located. (Source 16)
• Upper limit: We located no tolerable upper intake level or acceptable daily intake for chondroitin. LiverTox (2018) records only customary use: chondroitin sulfate in doses of 200 to 400 mg three times daily. (Source 16)
• Studied: The GAIT trial gave 1200 mg of chondroitin sulfate daily for 24 weeks. (Source 17)
• Studied: A 2025 systematic review reports chondroitin was most commonly given at 1200 mg daily, usually alongside glucosamine 1500 mg. (Source 18)

A common belief, and what the research shows

The belief: A chondroitin supplement contains the amount of chondroitin printed on the label.

What the research shows: A 2019 review of chondroitin quality control reports that "some raw material and dietary supplement products contain less than the claimed amount of CS, in some cases as little as 5–10%". The same literature lists what has been put in instead, including "sodium hexametaphosphate commonly known with the name of Calgon and used as a detergent or water-treatment additive, maltodextrin and lactose." Cochrane's finding of a small short-term benefit rests on trials of pharmaceutical-grade material, which is not the same thing as an arbitrary retail product.

Questions and answers

What is it?

Chondroitin sulfate is a glycosaminoglycan, a long sulfated sugar chain, that occurs naturally in cartilage. The supplement version is extracted from animal tissue, from various land and marine species, so the molecule differs between products. It is sold on its own and very often combined with glucosamine. (Source 5)

What does it do in the body?

In the body chondroitin is a structural component of cartilage, contributing to the matrix that cushions joints. What a swallowed dose does to that cartilage is not established. Cochrane found a small short-term reduction in pain in mostly low-quality trials, and a small reduction in joint space loss in two trials, while larger independent analyses found no clinically important effect. (Source 16)

Is it good or bad for you?

Mixed, and dependent on product quality. Cochrane found a small to moderate short-term pain benefit from trials it described as mostly low quality, and found fewer serious adverse events than on placebo. Against that, restricting to better-conducted or independently funded trials made the benefit uncertain, bleeding has been reported in people on warfarin, and many retail products contain less chondroitin than claimed. (Source 14)

How do you get more of it?

Only from supplements or from animal cartilage itself; the commercial ingredient is extracted from the tissues of land and marine animals. Trials have most often used 1200 mg a day, frequently alongside glucosamine 1500 mg a day. (Source 18)

If it is harmful, what reduces it?

Chondroitin is a normal body constituent, so there is nothing to remove in the usual sense. The situation in the literature where reducing exposure mattered is anticoagulation: in the FDA reports, cutting the supplement dose was followed by the INR returning towards the previous range. (Source 19)

Why might someone be low in it or missing it?

There is no dietary deficiency of chondroitin, because it is made by the body rather than required from food. The only low-level statement in the literature concerns diseased cartilage: glucosamine and chondroitin are described as reduced in osteoarthritis. Not taking a supplement is not a deficiency. (Source 16)

Which whole foods contain it or feed it?

There is no common whole food that supplies useful amounts. The ingredient comes from animal cartilage, the tissue used industrially as raw material, which is why gristle, tracheal cartilage and shark cartilage are the sources discussed rather than any everyday food. (Source 5)

What happens if you do not have it?

No deficiency state has been described. In placebo-controlled trials the people who took no chondroitin were not shown to fare worse on joint pain or joint space narrowing in the pooled large-trial analysis. (Source 15)

How can you test for it?

There is no clinical blood test for a person's chondroitin status. The testing described in the literature is of the product, not the patient: validated laboratory methods such as electrophoresis, enzymatic HPLC and size-exclusion chromatography are used to check a supplement's chondroitin content and animal origin. (Source 5)

References

1. Pharmacotherapy. Potential glucosamine-warfarin interaction resulting in increased international normalized ratio: case report and review of the literature and MedWatch database. 2008. PMID 18363538, DOI 10.1592/phco.28.4.540. Read the source
2. World Journal of Gastroenterology. Hepatotoxicity associated with glucosamine and chondroitin sulfate in patients with chronic liver disease. 2013. PMID 23983444, DOI 10.3748/wjg.v19.i32.5381. Read the source
3. Molecules (MDPI). Chondroitin Sulfate Safety and Quality. 2019. PMID 31013685, DOI 10.3390/molecules24081447. Read the source
4. Molecules (MDPI). Chondroitin Sulfate Safety and Quality. 2019. PMID 31013685, DOI 10.3390/molecules24081447. Read the source
5. Molecules (MDPI). Chondroitin Sulfate Safety and Quality. 2019. PMID 31013685, DOI 10.3390/molecules24081447. Read the source
6. Cochrane Database of Systematic Reviews. Chondroitin for osteoarthritis. 2015. PMID 25629804, DOI 10.1002/14651858.CD005614.pub2. Read the source
7. Cochrane Database of Systematic Reviews. Chondroitin for osteoarthritis. 2015. PMID 25629804, DOI 10.1002/14651858.CD005614.pub2. Read the source
8. Seminars in Arthritis and Rheumatism. An updated algorithm recommendation for the management of knee osteoarthritis from the European Society for Clinical and Economic Aspects of Osteoporosis, Osteoarthritis and Musculoskeletal Diseases (ESCEO). 2019. PMID 31126594, DOI 10.1016/j.semarthrit.2019.04.008. Read the source
9. Cochrane Database of Systematic Reviews. Chondroitin for osteoarthritis. 2015. PMID 25629804, DOI 10.1002/14651858.CD005614.pub2. Read the source
10. BMJ. Effects of glucosamine, chondroitin, or placebo in patients with osteoarthritis of hip or knee: network meta-analysis. 2010. PMID 20847017, DOI 10.1136/bmj.c4675. Read the source
11. New England Journal of Medicine. Glucosamine, chondroitin sulfate, and the two in combination for painful knee osteoarthritis. 2006. PMID 16495392, DOI 10.1056/NEJMoa052771. Read the source
12. Cochrane Database of Systematic Reviews. Chondroitin for osteoarthritis. 2015. PMID 25629804, DOI 10.1002/14651858.CD005614.pub2. Read the source
13. PLOS ONE. Randomized Trial of Glucosamine and Chondroitin Supplementation on Inflammation and Oxidative Stress Biomarkers and Plasma Proteomics Profiles in Healthy Humans. 2015. PMID 25719429, DOI 10.1371/journal.pone.0117534. Read the source
14. Cochrane Database of Systematic Reviews. Chondroitin for osteoarthritis. 2015. PMID 25629804, DOI 10.1002/14651858.CD005614.pub2. Read the source
15. BMJ. Effects of glucosamine, chondroitin, or placebo in patients with osteoarthritis of hip or knee: network meta-analysis. 2010. PMID 20847017, DOI 10.1136/bmj.c4675. Read the source
16. National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), NCBI Bookshelf. Glucosamine - LiverTox: Clinical and Research Information on Drug-Induced Liver Injury. 2018. Read the source
17. New England Journal of Medicine. Glucosamine, chondroitin sulfate, and the two in combination for painful knee osteoarthritis. 2006. PMID 16495392, DOI 10.1056/NEJMoa052771. Read the source
18. Nutrients (MDPI). The Safety and Efficacy of Glucosamine and/or Chondroitin in Humans: A Systematic Review. 2025. DOI 10.3390/nu17132093. Read the source
19. Pharmacotherapy. Potential glucosamine-warfarin interaction resulting in increased international normalized ratio: case report and review of the literature and MedWatch database. 2008. PMID 18363538, DOI 10.1592/phco.28.4.540. Read the source