There''s no evidence that people with hypothyroidism should avoid soy.
Standard treatment for hypothyroidism is synthetic thyroid hormone.
Theoretically, it''s possible that eating very large amounts of soy could impair
your body''s ability to absorb this medication. In such cases, signs and
symptoms of hypothyroidism may persist despite treatment with synthetic thyroid
Certain foods, medications and supplements — such as high-fiber foods, iron
and calcium supplements, and some antacids — may also affect absorption of thyroid
medication. To avoid this problem, take your thyroid medication on an empty
stomach and separate from such foods, medications and supplements.
If you take synthetic thyroid hormone, consult your doctor before starting
any new diets, medications or supplements.