Flaxseed, soy and low thyroid

From the American Thyroid Assn (an association of professional


“This is the first study to show that dietary supplementation with very high
doses of soy phytoestrogen (at levels typical of a vegetarian diet), may
result in a 3-fold increase in the risk of progression from subclinical to
overt hypothyroidism, suggesting that vegetarian patients with mild
subclinical hypothyroidism may need more careful monitoring of thyroid
function. The mechanism for this effect is not well understood.
On the other hand, high dose phytoestrogen also resulted in improvement in
cardiovascular risk factors despite worsening of thyroid function and may be
beneficial to patients with increased cardiovascular risk.”

[It should be noted that flaxseed contains 3x the phytoestrogen of soy, and
it is probably better absorbed from the gut (more digestible). With the
proliferation of flaxseed in both pet and human food, one has to wonder
about the increased numbers of hypothyroid animals and humans.]