In reply to a crap climber:
If you want a quasi science, rabbit hole, quack cures, partisan opinions and n=1 "studies", look no further than cartilage
It used to be stated as (assumed) fact that cartilage and joints in general just wore out, there was a finite resource it can't regrow because no blood supply, and it wearing out was inevitable.
This was illogical because if cartilage cannot be grown due to no blood supply then an adult couldn't have larger knees and more cartilage than a newborn baby so it is patently true that some mechanism to grow cartilage must exit.
Secondly, excluding relatively extreme exercise and non exercise scenarios, people who exercise more than average are less prone than average to develop significant osteoarthritis than people who exercise less than average.
So the "it just wears out" theory is completely debunked by both common sense (growth from baby to adult) and studies (exercise versus osteoarthritis)
It's reasonable to believe that there's one (or more) mechanisms that erodes cartilage and one (or more) mechanisms that repairs cartilage. If erosion rate is higher than repair it "shrinks" if the reverse it true it can "grow"
Enter the quackery and rabbit holes...
Various claims exist including individual accounts (i.e. various individuals not peer reviewed studies) that some substantial dietary changes can tip the balance back to growth. Nearly zero simple carbs, lower carbs in general and near zero processed foods are the general themes. Although the "magic" cure varies depending whose account you follow. Some people do swear that they were able to rehabilitate lost cartilage.
Welcome to the rabbit hole 😄