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.