Food intolerance occurs when the body is unable to dealt with a certain type of food. This is usually because the body does not produce enough of particular chemical that's needed for digestion of food, Some people are born with intolerances to certain foods, and others may develop intolerances much later in life. Symptoms of food intolerance vary greatly, and can be mistaken for the symptoms of an allergy

Most common food intolerance types : Diary intolerance - Cow's milk contains lactose and many people have a shortage of enzyme lactase - as a result the body can not break down milk sugar and this causes symptoms similar to irritable bowel syndrome. Alcohol intolerance - deficiency of an enzyme called aldehyde dehydrogenase can cause alcohol intolerance which will make people feel unwell. Gluten intolerance may result in damage to villi in the small intestine, which makes it difficult for the body to absorb water and nutrients from foods. There are other types of food intolerance, e.g. some people have intolerance to various chemical preservatives and food additives. Food intolerance in the body may lead to build up of toxic byproducts and histamine, which then mimic the symptoms of an allergy.

In food intolerance it can be difficult to determine the offending food causing an intolerance because if the immune system is involved, the response is likely to be IgG mediated and takes place over a prolonged period of time

Food allergy can be a complex disorder, further complicated by food intolerance, which can mimic the symptoms of an allergy. A food allergy is an adverse response to a food protein. Some of the first signs of a person suffering from a food allergy can be a runny nose, hives, itchy skin, tingling lips or tongue. Other signs can include tightness in the throat, hoarse voice, coughing, wheezing, stomach pain, diarrhea, and nausea or vomiting. True allergies are associated with fast-acting immunoglobulin IgE responses The most common food allergies in adults are Milk allergy shellfish, peanuts, tree nuts, sesame seeds, fish, and eggs, and the most common food allergies present in children are milk, eggs, and peanuts. Unfortunately, At present there is no cure for food allergy(ies). Treatment often involves adjusted diet, where the allergic person avoids specific foods.