Studies have linked wheat and dairy allergies to skin rashes and asthma. This was surprising to me, but I could repeat it by eating wheat one week and not the next. Food allergies occur when the immune system mistakes foods for invaders causing an immune reaction. The two major types of immune reactions here are IgE and IgG. IgE reactions cause symptoms anywhere between a few minutes and two hours after eating the food. This generally includes stomachache, gas, etc., and may also cause fatigue and mental fogginess.
Food allergies can trigger migraines and migraine equivalents.
IgG reactions are generally delayed reactions occurring anywhere from two to twenty-four hours after consuming the food. These reactions are often in the form of fatigue and fogginess. Frequently if the person has not eaten a food in several days, no reaction may occur. This means that some foods will cause reactions only hours after you have eaten them for the second time in two or three days. If you've read the literature on Candida, you are probably completely confused about what to eat and not to eat.