Ingredients to look for in thyroid supplements. as indicated in our table below this section, the most common thyroid supplements include: vitamin b-12, iodine, magnesium, saraparilla root, zinc, selenium, copper, manganese, molybenum, ginseng, l-tyrosine, schizandra, ashwagandha root, bladderwrack, cayenne pepper, and kelp. if you are looking for in depth analysis on each nutrient’s.