Numbers Game: Answer

A single Brazil nut provides 97.5% of the daily selenium requirement.

Pretty nifty, huh?

This is a particularly valuable tidbit of information for vegans, since the vast majority of foods high in selenium are animal-derived.

That doesn't mean you can't get too much of a good thing.

Since the Upper Limit for selenium is set at 400 micrograms, snacking on a half dozen Brazil nuts every day could set the stage for a condition known as selenosis, which can result in in hair loss, fatigue, and intestinal discomfort.

This is literally a "one a day" recommendation.