Studies show that consuming large amounts of soy, which contains goitrogens, does not significantly affect thyroid function.

“when you look at studies that assess actual thyroid function in people that consume large amounts of soy you find that thyroid function remains unaffected in fact the longest randomized control trial that we had which followed 403 menopausal women for two years reported that consuming 120 milligrams of soy isoflavones daily over that two year period had no significant effect on thyroid function other than a trend for a reduction in t4 and that reduction was from 1.2 to 1.1 which isn't clinically significant by any extent”