Can too much selenium suppress the thyroid?

[Ippodrom47]

For instance, from large quantities of brazil nuts or supplements.

 

[Dr. B]

For instance, from large quantities of brazil nuts or supplements.

yes, its a known effect. upper limit used to be 400mcg according to the fda, it may have been lowered to 300mcg a couple years back.
its hard to overdose from foods unless you have a lot of brazil nuts. maybe those have other factors preventing an overdose even if the amount is above 300mcg.
some sites say its a balance between iodine and selenium so maybe higher doses could be tolerated with more iodine. iodine is also risky though, selenium/iodine are risky to supplement.

 

[Hans]

For instance, from large quantities of brazil nuts or supplements.

I few studies I read mentioned that up to 600-800mcg for food is likely to be safe, but perhaps I should have looked up their references. But regardless, if you get your selenium from food, I'm sure you're much more likely to be safe. Plus, you'd have to overeat on certain foods to really overload on selenium and chances are that you'll lose your taste for that food before you become overloaded.