# Naturally Occurring Sulfites or Sulphites form

In the following link, it says that the product

May contain trace amounts of naturally occurring sulfite residue

I asked the manufacturer about it and the explanation I got was:

The trace amounts of naturally occurring sulfites are present in hydrolyzed collagen (as are most other proteins as well). The sulfur that holds the bonds between the molecules is broken up from these processes and changes them to sulfite

Does anybody knows the exact chemical form of the sulfite that this product contain?

Is it in the form of an anion or in the form of a compound?

When collagen is hydrolyzed, sulfite ions ($$\ce{SO3^2-}$$) are released. Usually manufacturers filter out the residues, but may some still remain behind, which is why they put the warning on the label.