I remember at the time of the Beijing Olympics, the best customers for the MacDonalds at the Olympic Village were apparently Usain Bolt and Jeremy Wariner. We don’t know exactly what they were doing the rest of the time, but with the exception of maybe yams, Usain has a certain reputation…
I remember Michael Johnson some years ago saying something along the lines that the weights and track training for being a sprinter will make you look good no matter what you do, so he didn’t follow any special diets.
The scientific data for nutrition seems to apply to protein–you need sufficient quantity to allow for regeneration–which can be found in the ACSM guidelines for athletes and probably elsewhere. You obviously need sufficient calorie content and perhaps B-complex supplements to allow for regeneration. My sense, though, is that beyond this, everything that can be shown to actually work for performance is banned.