By and large, it's recommended that supplementation should be in response to blood test results for ferritin, folate, B12, vitamin D etc. as it's usually advised here that thyroid hormones (your own or supplemented ones) work better when vitamins and minerals are in the optimal range.
SlowDragon has lots of suggestions about appropriate diet for Hashimoto's see, e.g., this: healthunlocked.com/thyroidu...
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