Which supplements rebuild cartilage?

The imaging test, and the candidates that have been through it

Which supplements rebuild cartilage is a question whose verb decides how it must be answered, because rebuild is a structural word, it means more cartilage or thicker cartilage or cartilage that stopped thinning, and the only test of a structural claim is imaging, MRI cartilage volume and composition or joint space on X-ray, so the honest page puts every candidate on the shelf through the imaging test and reports what each showed, which is the same thing. Glucosamine and chondroitin first, the oldest names on the joint shelf and the ones most readers mean. Their story is the aisle's cautionary benchmark: after decades of small positive trials, the large independent randomised trials in knee osteoarthritis failed to support the category's symptom promises against placebo, and the trials that included imaging arms, measuring joint space narrowing on X-ray and cartilage on MRI over two to three years, found no meaningful protection of cartilage and no regrowth, so glucosamine and chondroitin have been through the test and did not pass it. Hydrolysed collagen second, this site's own aisle: the joint comfort trials at around ten grams a day for twelve to twenty-four weeks measured pain and function by questionnaire and found modest gains, and none of them measured cartilage by imaging, so collagen has not been through the test at all, there is nothing to pass or fail, and any tub that says collagen rebuilds cartilage is describing a scan that was never taken. Undenatured type II third, at around forty milligrams: small symptom trials in osteoarthritis and exercising adults, an oral tolerance mechanism, no imaging outcome. Oral hyaluronic acid fourth: small symptom trials, a molecule that is digested rather than delivered to the joint, no imaging. Curcumin fifth: modest reductions in knee osteoarthritis pain against placebo in short trials with heterogeneous formulations, a pain result and no structural claim or measurement. Fish oil sixth: a two-year randomised trial comparing a high dose with a low dose in knee osteoarthritis found no advantage for the high dose on pain or function and no structural benefit on imaging, the omega-3 joint evidence lying in rheumatoid arthritis instead. Vitamin D seventh, because it is often sold for joints: the trials that gave vitamin D to people with knee osteoarthritis and scanned them found no slowing of cartilage loss and no symptom benefit in those who were not deficient, so it too has been through the test and did not pass. Seven candidates, and the imaging test's verdict is the same for each: no oral supplement has rebuilt or measurably protected articular cartilage in a human joint, whatever it did to a symptom score.

Why the test comes out that way, and the shelf ranked by the evidence it does have

The test comes out that way for a reason the cartilage biology makes plain: adult articular cartilage is avascular and sparsely populated by chondrocytes that cannot migrate to a defect or divide to replace lost tissue, so there is no cell population for a swallowed molecule to stimulate into rebuilding and no blood supply to carry it there in quantity, and the tissue's capacity for repair is so limited that cartilage restoration, where it exists at all, is a surgical field of cell implants and grafts for focal defects in selected knees, which is the plainest evidence there is that nothing swallowed does the job, since no operating theatre would exist for a problem a capsule solved. What the shelf does have is symptom evidence, and a reader who wanted comfort rather than rebuilding can rank it honestly. Hydrolysed collagen's comfort trials, modest and mostly industry-funded, at ten grams over months, and curcumin's pain trials, modest and short, sit at the top of a low hill; undenatured type II and oral hyaluronic acid sit below them on smaller data; glucosamine and chondroitin sit at the bottom as the benchmark for what a category looks like after the large trials arrive; fish oil and vitamin D belong to other conditions. Above the whole hill, and not on the shelf, sit the interventions the osteoarthritis guidance puts first, exercise, which improves the composition of the cartilage that remains on contrast MRI, weight management, which takes around four kilograms off the knee per kilogram lost with each step, and a physiotherapist for the muscle around the joint, with supplements absent from the recommended pathway. The register agrees with the imaging: no supplement holds an authorised claim for cartilage, and the only cartilage sentence on any label is vitamin C's, that it contributes to normal collagen formation for the normal function of cartilage, a maintenance sentence describing what the body does with what it has. The worked example is comfort research on its true terms and not rebuilding: two capsules, 1200mg hydrolysed type 1 marine collagen with 12mg vitamin C plus zinc, 120 for £16.99 at 28p a day, lab tested and UK made, below the ten-gram comfort research dose, taken for vitamin C's cartilage sentence, with no scan promised because none has ever changed. Which supplements rebuild cartilage: none has on imaging, seven have been asked and the same answer came back each time, and the reader who wants a joint to last works on everything around the cartilage instead.

What to check on the label