4. Soy
There is a fair bit of controversy over soy. Once considered a healthful substitute to meat products, in recent years evidence has surfaced that suggests soy can have a negative effect on thyroid function. Soy can impact the ability of your thyroid to absorb iodine, so if you are already deficient, this can significantly up your risk of developing hypothyroidism.
However, many researchers say that as long as you aren’t eating a ton of soy nor have a pre-existing iodine deficiency, you aren’t at an increased risk of developing an underactive thyroid. Moderation is important when it comes to soy, especially if you are a man, as soy can also mimic estrogen in the body.