I'm not sure on the dosing, but I think that Brazil nuts are very high in selenium.  I guess you'd have to get imported nuts though.  :/

to me i can't see any circumstances by where somebody would benefit in anyway from taking a selenium supplement...not even to save time.

if you look at somewhere like nutrition data you'll see that all you need to do is consume a couple of brazils a day to get more than enough of this important anti-oxidant mineral.

my advice would be to soak the brazils over-night to aid digestibility - theyre surely cheaper than the synthetic pills too?

+ they taste ok - and give you other natural minerals to boot

Does Cordain advises selenium supplements?. This diet is rich in food that contain this mineral such as nuts, meat, fish and eggs.