Adverse reactions to foods are common and increasing problems worldwide. It is important to differentiate between the different forms of adverse reactions to foods, in particular the difference between food intolerance and food allergy. Food allergy is an adverse immunologic response to food and typically rapid in onset, whereas food intolerance is consequence of a variety of non-immune mechanisms and slow in onset. It has been difficult to diagnose food intolerance because of lack of diagnosis measure. There are now effective findings to identify food intolerance, and paradigms with food allergy are shifting. Food intolerance affects virtually every part of the body-from mildly uncomfortable symptoms to severe illness. While there is no known simple ``cure`` for food allergy and food intolerance, there are a number of measures that will help avoid and lessen symptoms and correct the underlying causes. We focus the diagnosis and treatment of food intolerance through various views.