Update: I did a search and found the nih site had an article 3/2006 about the effects of soy protein and soybean isoflavones on thyroid function which included healthy adults and hypothyroid patients. http://www.ncbi.nlm.nih.gov/entrez/q...=pubmed_docsum
They found little
evidence that in people having normal thyroid gland function, iodine abundance individuals, soy foods, or isoflavones adversely affect thyroid function. Remember, this is WITH plenty of iodine.
HOWEVER, some evidence suggests that soy foods, by inhibiting absorption
, may increase the dose of thyroid hormone required by hypothyroid patients.
I am sure there is more info somewhere - just don't have the time to research, so I'll continue to stay away from soy.