This is true for me, I'm allergic to the stuff and it causes, within minutes of ingestion, blinding headache, intense nausea, and diarhea or however you spell that awful word. I have read some with more severe reactions can faint or worse. But surely there is a test that could be done, ahead of time, to weed out people like me? And I know that I am not the norm, that is, the vast majority of people do not have a problem with phenalanaline, so they should be able to easily find enough subjects to test this theory on that would not have a problem with metabolizing the phenalanaline. I guess the point is, how many PWP can there be that also cannot properly metabolize phenalanaline? I would think not so many that they could not do a study like Ron is suggesting.