I have just been diagnosed with hashimoto disease. Is there any special diet?

Avoid toxic foods. Avoid sugars, fried foods, vegatable oils like canola & soy, meats that are cured wth nitrates & nitrites, aspartame, splenda, partially hydrogenated vegetable oils, maragarine, soy based products, sweetened beverages like juice & soda, microwaved foods, artificial colors & flavors. All of these products cause damage to the cells, tissues & organs in your body contributing to various diseases.
No. If your thyroid gland becomes underactive, you will need to take thyroid hormone replacement. No special dietary changes are needed for hashimoto disease.