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Good luck with your research.  My Ph.D. is in Research & Statistics; my
minor is in Psychology.  I am also 'irritable' tonight but not because
of my bowels but because I have a gluten intolerance and, five days ago,
I took a vitamin E capsule that listed 'di-alpha tocopheryl acetate'
as the only ingredient.  Four days of watery diarrhea, stomach aches
and emotional distress later, I find that this capsule also contained
wheat germ oil...loaded with gluten.  I do not have 'irritable bowel
syndrome' nor do I have 'psychological problems'.  I have a medical
problem that labeling laws make it very difficult for me to live with.
One slip...one stinky little inadequately labeled vitamin E tablet
containing an ingredient left off the label...and I suffer for four
days because of it!  I'm irritable, yes.
 
By the way, my bowels work just fine when I stay away from gluten.
 
BJ