Hey there. As far as I know it is an old wives tale that it will give you arthritis as the 'cracking' sound is nothing more than bubbles of air popping. Air gets trapped in the synovial fluid around the joints, such as knuckles, and when any kind of pressure/movement is applied the air is forced out causing the bubble to pop.
It's probably not a great idea to do it more than you need to but other than that I don't know any remedy - cod liver oil, as the other guy suggested, sounds like a sensible idea however.