[QUOTE=sparkie;2795679] Can selenium be found naturally in foods or does it have to be taken as a supplement? Is it truly as simple as selenium or is something else involved here? [QUOTE]
Hi Sparkie,
Selenium is found in a variety of foods. Unblanched brazil nuts are an excellent source; one ounce can provide up to 3x the RDA for Selenium. Canned tuna -- 3.5 oz will give you 60 mcg.; 3 oz. of ground beef, about 30 mcg. There are many other foods that contain Se as well.
A low free T3 COULD be as simple as selenium deficiency. However, for many people in our modern world, those environmental & food goitrogens may play a role in damping conversion. There is increasing evidence being put forward by respected scientists that fluoride in water, food, juice, and dental care preparations, is bad for all of the enzyme systems in the body. In past, MDs used fluoride to block hyperthyroid.
There have been some reports that increasing Omega 3 fish oil (not O3 flax) improves thyroid function, though at the moment I don't recall whether or not it's a T4-T3 conversion-based influence.
And of course there are hormonal issues: progesterone & testosterone increase conversion, while estrogen generally binds TH but I'm not sure what it's effect on conversion, per se, is.
Best wishes.
.