If you soak chicken bones in vinegar, the vinegar will react with the calcium in the bones and weaken them so that they will become soft and rubbery, as if they had come from a rubber chicken. Vinegar is a mild acid, which breaks down calcium. CLR just does it a lot faster.
It is the calcium in your bones that makes them hard and strong. As you age, you may deplete the calcium faster than you replace it. If too much calcium is lost from your bones, they may become brittle and susceptible to breaking.
Exercising and eating a diet that includes calcium-rich foods can help prevent this from happening. That is why your MOM always says “Did you drink your MILK?” Thanks Mom.