Salts are a general name for anything made from an acid and a base....mostly they are ions coming together to form compounds made with ionic bonds.
NaCl or salt as we know it is the most famous.
Ionic bonds can come apart easily...so the NaCl disassociates and allows the Cl ion to reattach to other stuff. In our case we're hoping it reattaches to Br or F that's come loose from iodine.
Brownstein says if bloating or high blood pressure presents a problem use potassium chloride. I would think that Mg chloride would also work (i.e nigari)