For the last couple of years before I was medically retired, I worked in the Outpatients dept.
I worked in various clinics including Orthopaedics. I overheard several consultants say to patients, who asked about taking supplements for joints, (usually those awaiting hip/knee replacements) that it does no good whatsoever and not to waste their money - once the damage is done it's done.
I don't know if it makes a difference taking them when you're younger or not.
I remember being given castor oil and vitamin C in the winter when I was a child.
I have arthritis in most of my major joints, so who knows.