One study found OTC thyroid supplements containing detectable levels of active thyroid hormone.
Thyroid Supplements Contain Actual Thyroid Hormone...
"Surprisingly, nine out of ten supplements showed detectable amounts of t3
, ranging from 1.3 mcg to 25.4 mcg per tablet.
Taken at the
recommended dosage, five of the
ten supplements delivered t3
quantities in excess of 10 mcg/day, and
four delivered t4
quantities ranging from 8.57 to 91.6 mcg/day.