For what it's worth:

A few years back I was suffering from some pretty severe health problems. The major manifestations were cognitive and mood related. Often when I was saying a sentence I would become overwhelmed halfway through and would have to consciously force myself to finish what I was saying.

Long story short, I started treating my diet like a controlled experiment and, after a few years of trial and error, have come out feeling better than I can ever remember. If you're going to try self experimentation the three things I recommend most highly to ease the analysis process are:

• Don't eat things with ingredients in them, instead eat ingredients
• Limit each meal to less than 5 different ingredients
• Try and have the same handful of ingredients for every meal for at least a week at a time.