I've doubted his process from the start - I remember reading a third person's comment that pointed out he had forgotten to add iron - and his subsequent reply that this mistake was the cause of his feeling bad. I know nothing about nutrition (except that it's not a very good science, if it's science at all), yet iron is obvious even to me. To miss it shows that he didn't really do much double checking, much less cross-referencing or careful deliberation of the ingredient list.

I'm really hopeful about Soylent - I'd even jump in and risk poisoning to test it myself, if I were living alone. If anything, this experiment highlights how untrustworthy and limited our dietary knowledge is (and should motivate us to improve it). If this fails due to a new form of scurvy, the cause can be found and the experiment retried. If it fails due to not having read information that's already out there, well, that's a downer.