The more I think about it, the less adding nitrogen to beer fermentation makes sense to me. I haven't found many hard numbers for yeast available nitrogen content in wort, but one study found a typical range to be 1-2g/L, or 1000mg/L - 2000mg/L.
Brewers' yeasts' nitrogen requirements aren't published, but wine yeasts' are. The "standard" winemaking yeast available nitrogen recommendation at 28 Brix (1.120) would be 375-425mg/L. Wine yeast nitrogen requirements vary pretty widely, with some needing nearly twice as much as others. I assume beer yeasts are similar in that regard. Even if the yeast needed twice the nitrogen, that'd only be 850mg/L, well below the minimum reported amount of yeast available nitrogen in wort.
In order to need nitrogen for a wort fermentation, you'd need to have a very nitrogen-deficient wort, and a yeast with exceptionally high nitrogen needs.
EDIT: Thanks MX, fixed it. Nitrogen =/= nutrients.