- Metals are characterized, in part and in general, by electrical conductivity, which means the electrons in the material are able to move relatively freely. Due to the movement, the diffusion, within the metal of the atoms and electrons metals are generally very ductile, bendable. Unfortunately, aluminum has been linked to Altzheimers and iron overdose can be a fatal problem. Metal is awesome but too much of it in your body can be a bad thing.
- Polymers are characterized by chains of mer units, thus the name poly-mer means many mers. The difficulty with polymers is that chemicals are used to join the mer units together. Bisphenol-A which has been linked to a slew of bad diseases caused quite the uproar a few years ago. No matter how stringent the cleaning process, some of the catalyzing chemical, like Bisphenol-A will remain in the polymer. If it was possible to create and isolate a single long chain of a polymer it would be an incredibly strong nano wire. That is in fact how climbing ropes and ropes used for shipping and industrial setting are so strong. The polymer is continuous from one end of the rope to the other.
- Ceramics are something in between. They are very orderly like polymers yet they exist in bulk three dimensional organization like metals. Ceramics are not very electlically conductive at room temperature because the electrons around each atom are not free to move about. That means that ceramics are less ductile than metals. This means that the material also is stronger than metals. Think carbon fibers, because they are ceramic. The advantage for eating is that unless a conscious effort is made to scrape and scratch the ceramic, it will not release atoms as easily as metal and it has nothing to leech like polymers.
I recommend ceramic when it comes to eating. Unless you are anemic in which case using cast iron cookware will help boost that iron in your body.