What's the difference between food allergy and food intolerance? I get this question a lot when people find out my son is gluten intolerant; they typically think that means he's allergic to gluten. But intolerance or sensitivity to a food is not the same as an allergy. With a true gluten allergy, the body's immune system reacts to something (typically a protein, like gluten) and attacks it as an invader; in this case, the body can never safely handle even a tiny amount of gluten (this is celiac disease). With a sensitivity or intolerance, the reaction is not an immune response; instead, the digestive system reacts to something as an irritant. The reaction is typically more delayed and can build up over time. (That's what happened with my son; he felt progressively worse over about 18 months before we figured it out.) It's easy to go a long time feeling discomfort of various sorts without realizing that you might have a food intolerance; there's no medical tests that can definitively pinpoint an intolerance, only a true allergy. So if you're feeling sick in some way -- it could be fatigue, brain fog, skin rash, joint pain, or any other dis-ease, not just a digestive disturbance -- think about what it could be that you're eating or drinking. An elimination diet is a simple way to find out whether you have a sensitivity to a certain food; some the most common offenders are soy (especially processed), dairy, wheat, nuts, and citrus.