Sentence:  The effect of drugs that act on the iodide concentrating mechanism can be counteracted by addition of relatively large amounts of <WSD>iodine</WSD> to the diet . 
Meaning of the word marked with <WSD> tags:  a nonmetallic element belonging to the halogens; used especially in medicine and photography and in dyes; occurs naturally only in combination in small quantities (as in sea water or rocks)