I wish it were that simple, since mine is more of an autoimmune condition combined with food allergy (gluten intolerance) there are somethings I can have once or twice that will send me into a "flare" after several times (a good example is the gums they use as conditioning agents for gluten free baked goods. I can have GF baked goods 2 or 3 times a week, max, but more than than sets me off, FOS did the same thing). I'm a sensitive celiac, so gluten/wheat is out, including oats and even "sticky" rice. Glucosamine/chondroiten set me off, I don't know why (which broke my heart, it made my back feel like a million bucks). Soy products do funny things to me sometimes, as do artficial colors/flavors.
Some thermogenics give me palpitations/paranoia, and since they're blends no knowing WHAT is causing the problem, I can take Stimulant-X but only very rarely as it totally wipes out any ability for me to sleep that night. Even some regular dietary supplements give me strange side effects if taken to excess (I'm the only person I know that can take too much CoQ 10, 60 mg a day is the perfect dose for me, 120 mg a day will start to give me REALLY freaking weird feelings in my chest and I will get palpitations). Sesapure broke me out in a rash (no idea why, maybe the lignans because sesame seeds don't bother me).
It's lots of fun being me
<sarc> The bitch of it is, I don't make this crap up, my health just went haywire when I hit my 30s. I have to try stuff, and give it a full two weeks to a month before I can say, "this is good for me" or "nope, gotta cut it out."