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Glucosamine and chondroitin · Weak evidence
What glucosamine and chondroitin are for
The short answer. Glucosamine and chondroitin are the classic joint supplements, and also the ones that have aged worst. The largest independent trial, with almost 1600 patients with knee osteoarthritis, found no differences versus placebo across the study as a whole. Only a subgroup with moderate or severe pain showed improvement with both combined, and that finding is exploratory.
Reviews find no consistent effect. It is listed because it sells, not because it works. No figure on this page is attributed to a specific product: the effect belongs to the ingredient and every number carries its source next to it.
01 What it does and how much
Each row is a measured effect, with the figure the study gives and the source number. Where the evidence gives no figure, the column says so instead of making up a percentage.
| Effect | How much | Detail |
|---|---|---|
| Knee pain across the whole trial | no difference | Neither glucosamine, nor chondroitin, nor both together beat placebo in the main analysis of the GAIT trial. [1] |
| Subgroup with moderate or severe pain | improvement with the combination | A subgroup analysis, which is a signal to investigate and not a conclusion. Worth knowing that it is exactly the figure marketing uses. [1] |
| Trial dose | 1500 mg of glucosamine and 1200 mg of chondroitin | They are the reference amounts for comparing products. Many tubs fall well short by splitting the total across several ingredients. [1] |
| Safety | good in the trial | The problem with these supplements is not risk, it is efficacy. That helps the decision: what you are risking is money. [1] |
02 How to take it
- Dose. 1500 mg of glucosamine and 1200 mg of chondroitin a day if you decide to try it.
- When. With food, in one or several servings.
- How long before you notice it. Trials assess at 6 months. If you notice nothing at 3, that is a signal.
Details that change the result
- Count the milligrams per serving and how many capsules you need a day: many cheap tubs are cheap because they carry half the dose.
- Glucosamine is usually derived from shellfish: relevant if you have a shellfish allergy.
- In osteoarthritis, what does have strong evidence is strength exercise and weight control.
- With anticoagulants, chondroitin may interfere: ask first.
03 When it makes sense and when it does not
Worth it if
- Moderate or severe joint pain, as a three-month personal trial with low expectations.
- It already works for you subjectively and the cost is worth it to you: it is safe.
Not worth it if
- As prevention in healthy joints: nothing supports it.
- Instead of strength training and weight control, which is what does have evidence.
- With a shellfish allergy, without checking the product’s source.
04 Sources
Every figure above comes from here. They are position stands from scientific societies, meta-analyses and peer-reviewed reviews: if a claim cannot hang from one of these lines, it is not on the page. References are cited in their original form.
- Clegg DO et al. Glucosamine, chondroitin sulfate, and the two in combination for painful knee osteoarthritis. N Engl J Med. 2006;354(8):795-808. 1500 mg de glucosamina y 1200 mg de condroitina; sin diferencia frente a placebo en el analisis principal. doi:10.1056/NEJMoa052771
This is not medical advice. It is what some studies say about an ingredient, not a protocol for you. With an illness, medication or pregnancy involved, the decision belongs to a healthcare professional who knows you.
Questions about glucosamine
Answered with the data on this page
- Do glucosamine and chondroitin work?
- The largest independent trial, with almost 1600 patients with knee osteoarthritis, found no differences versus placebo in the main analysis. Only a subgroup with moderate or severe pain improved with the combination of both, and a subgroup analysis is not a conclusion. That is why they are rated here as weak evidence.
- What dose of glucosamine should you take?
- The reference trial used 1500 mg of glucosamine a day and 1200 mg of chondroitin. That is the figure to compare any product against: many combination products split the total across glucosamine, chondroitin, MSM and collagen and end up far from those amounts.
- Do they help prevent injuries if I train hard?
- There is no evidence supporting that in healthy joints. What does protect the joints of people who train is sensible load progression, strength around the joint and enough rest.
- Is taking collagen the same?
- No, which is why they are in separate tables on this site. Collagen is sold as a powder and compared per kilo; glucosamine and chondroitin come in capsules and are compared per capsule. They also do not have the same evidence behind them or the same proposed mechanism.
And now, which to buy
Prices, kept apart from the evidence
This page explains what glucosamine does and deliberately names no brand. The comparison is the other half: 101 products from 10 stores from €0.047 per capsule, sorted by price and by how verifiable their certification is.
Other guides
What each supplement does, with its sources