Sometimes they do catch stuff that a regular doctor misses (which is more of an indictment of the doctors in question). My girlfriend has a thyroid balance problem, blood tests confirm it. Her doctors (an internist and a endocrinologist) kept giving her higher and higher doses of medication that were not helping. She went to a naturopath who ordered a food allergy panel. It came back that she is allergic to wheat, whey, gluten, eggs, peanuts, soy, and several other things. Most of the allergies were minor, but whey and soy are just short of the "you will go into anaphylactic shock and die" level.
She changed her diet and the thyroid problem mostly went away, it is controllable by low dose medication now. She gets sick a lost less often and recovers quicker. We're hoping that long term avoiding those foods will remove the need for medication entirely.
