Agoraphobia is caused by the over-producton of stress hormones which usually result if blood sugar levels are not properly controlled. When blood sugar level fluctuate the brain is not supplied with proper levels of biological energy, necessary in the production of feel-good neurotransmitters such as serotonin. When the brain is deprived of energy it will trigger the release o stress hormones - such adrenaline and cortisol - that can cause the agoraphobia. I would suggest that you have a look at the Hypoglycemic Diet, which is similar to the diabetic diet to make sure your body receive the proper nutrients. When you have unstable blood sugar levels your body is under stress and may affect your immune system triggering all sorts of illnesses.