Will soy wreck my thyroid?
If you have hypothyroidism and you chase your thyroid replacement with a tall glass of soy milk, yeah, that could interfere with your body’s ability to absorb the medication, since you’re supposed to take it on an empty stomach. If you have subclinical hypothyroidism and you start taking large doses of soy protein supplements, it's possible you might develop full-blown hypothyroidism.
“Only very high doses of soy phytoestrogen supplementation may induce clinical hypothyroidism in a minority of patients with subclinical hypothyroidism,” Dr. Jorge Mestman commented on a study about the effects of soy on supplements on thyroids.
So, don’t take mega-doses of soy supplements… but you shouldn't be doing that, anyway.
No supplements, got it. So what type of soy products should I eat?
The experts interviewed for this article were unanimous in their belief that organic, unprocessed, or fermented soy products are most beneficial. They all said it’s a bad idea to take soy protein and soy supplements.
“What you have to look out for is non-organic soy, which considering that 91% of soybeans are genetically engineered is hard to avoid,” says Dr. Gabrielle Francis. “Only eat brands that list organic soybeans in the ingredients list. Avoid products with soy protein isolates as well.”