Posted by Larry Hoover on September 19, 2003, at 20:00:59
In reply to Soy » Larry Hoover, posted by tealady on September 14, 2003, at 5:40:20
> I think ALL of the posters on the hypothyroid forum, have found they feel less hypo with the elimination of soy..and all who have tried an elimination diet and retested a month later, have responded with hypo symptoms..at least that I have read. They were all female I think.
> I think soy is a goitrogen, but it has other effects on thyroid hormone utilization(unsure what) besides the actual thyroid hormone production.A quick look at the soy/thyroid connection was rather revealing. One of the isoflavones, genistein, alters thryoid function in two distinct and deleterious ways. First, it is an alternate substrate for the iodinating enzyme, so it consumes iodine without contributing to the formation of T4 (that's called competitive enzyme inhibition), leading to functional iodine deficiency. Second, under conditions of oxidative stress (e.g. high peroxide levels), the genistein binds permanently to the reactive site of the iodinating enzyme, inactivating it entirely. That's irreversible non-competitive enzyme inhibition.
For anyone whose thyroid hormone production is already impaired or marginal, genistein could simply be the straw that broke the camel's...uhhh....neck, I guess.
Both forms of enzyme inhibition are associated with goiter formation.
Lar
poster:Larry Hoover
thread:259853
URL: http://www.dr-bob.org/babble/alter/20030903/msgs/261734.html