food sensitivites, inability to produce IgA

http://www.enzymestuff.com/conditionsensitivities.htm



Just part of what it says:
Intolerances
Conventional medicine can easily diagnose and treat allergies for foods or inhalants. Here, the so-called RAST test plays a very important role, because this test can demonstrate the presence of IgE. However, demonstrating the presence of intolerances is more difficult. In this situation, similar to the case of classical allergies, the body responds abnormally and, in addition, the immune system does not produce IgE. It quite often takes much longer for complaints to come on, thereby masking the possible link between the offensive substance and the complaints themselves. These are only a few of the reasons why food intolerance is considered a fairly controversial concept in conventional medicine. Intolerances can be responsible for a wide variety of complaints which, at first glance, seem to lack a plausible explanation. Intolerances can manifest themselves as:

gastrointestinal problems (stomach aches, cramping, bloating, bowel problems)
headache and migraines
hypoglycemia
depression, anxiety, unexplained mood shifts
sleeping disorders
joint and muscle aches; fatigue
asthma, rhinitis, or sinusitis
skin problems (eczema, rashes, acne, etc.)
Notice that the last ones are very similar to the reactions commonly seen in true allergies. There is overlap in symptoms. True allergies can also cause behavioral or physical problems besides the common histamine reactions.