I am currently dealing with Hashi's and had the high TPO and TG anti bodies. I had the 5 Amalgam fillings in my mouth replaced by a qualified dentist, and after about 6 months my TPO ab's were virtually non existent. I am still dealing with the TG ab's and they are a much tougher nut to crack, but through dietary modification I have them down to around 1.5 on an acceptable scale of 0.0-0.9 IU/mL.
Another good place to look into is a series of books called Eating Right for your Blood Type. A lot lot the foods we love to eat can ultimately cause an allergic reaction and end up weakening the immune system. I find when I eat some of the foods I should be avoiding I feel tired shortly afterwords. This validates their recommendations, IMO.
Best of Luck.