How much selenium is too much?
It has a lower upper limit than most minerals, so stick to the dose on the pack and count anything you are getting from a multivitamin as part of the total. If you are unsure, a pharmacist can add it up with you.
Which form is best absorbed?
Selenium yeast and L-selenomethionine are generally taken up more readily than sodium selenite. The form is stated on the pack, and it is the first thing worth checking.
Can I just eat Brazil nuts instead?
Many people do. The catch is that the selenium content depends entirely on where the nuts were grown, so the amount you get varies a great deal from bag to bag.
Should I take it with food?
It is generally well tolerated either way, though taking it with a meal suits most people and makes it easier to remember.