Whats the difference between food allergy and food intolerance?
A food allergy occurs when an overactive immune system produces a response against specific foods that are otherwise harmless e.g. egg, milk, peanuts, tree nuts, fish and seafood. Food allergy is mainly a problem of infants, toddlers and young children. Fortunately most grow out of their food allergies before school age. In adult life about 1% of people have a food allergy. Food intolerance occurs when individuals react adversely to some of the naturally occurring chemicals in food and to common food additives such as the preservatives, artificial colours and flavourings. Reactions are dose dependent and different people will tolerate different amounts of any given chemical. Both food allergies and intolerance can lead to people eliminating a number of important foods from their diet. It is essential that food allergy or intolerance be properly diagnosed and that an Accredited Practising Dietitian is consulted in order to develop an appropriate diet that meets the nutritional needs of
Food allergy and food intolerance are both types of ‘food sensitivity’. When someone has a food allergy, their immune system reacts to a particular food as if it isn’t safe. This reaction can make them very ill. People can be allergic to one or more foods. If someone has a severe food allergy, this can cause a life-threatening reaction called anaphylaxis (pronounced ‘anna-fill-axis’). Anaphylaxis affects the whole body, often within minutes of eating the food. Food intolerance doesn’t involve the immune system and is generally not life-threatening. But if you eat a food you are intolerant to, this could make you feel ill or affect your long-term health. There is also a Food Standards Agency factsheet on food intolerance. See www.eatwell.gov.uk/allergy Symptoms of an allergic reaction The symptoms of an allergic reaction can vary and the reactions can be more or less severe on different occasions. Even if you try very hard to avoid the food that you are allergic to, you may still eat it
SC: In fairness, it can be tricky sometimes. The difference, fundamentally, is that it’s not really immune-mediated. Food intolerance is often very consistent, just like food allergy. When you have the exposure, you have these unpleasant symptoms, but there’s no potential for anaphylaxis with food intolerance. With lactose intolerance, which is one we understand well a lot of intolerances we don’t understand well the person just has a relative inability to digest milk sugar and so it’s not a protein-related problem, which is what an allergy is; it’s the sugar. And with the milk sugar not being digested properly, it causes cramping and bloating and diarrhea. So with food intolerance, the person really doesn’t have to strictly avoid the food. They often will avoid it because it’s unpleasant, but there’s no serious adverse effect. With a food allergy, you can’t do that. YH: What if it’s just a mild allergy? SC: Being allergic is like being pregnant. You either are or you aren’t. When peop
And why is it important to know the difference? If you have a food allergy, eating even the smallest amount of that food may trigger a serious reaction. With food intolerance, you may be able to eat small amounts of problem foods without a reaction. With an allergy, the immune system mistakenly identifies a food as harmful, triggering immunoglobulin E (IgE) antibodies to fight the substance. Signs and symptoms usually develop within minutes and may include tingling in the mouth; hives; swelling of the lips, face, tongue and throat; wheezing or breathing difficulties; dizziness; abdominal pain; diarrhea; nausea or vomiting. Food intolerance, where a symptom is triggered by a food or substance, is much more common than food allergy. Only about 2 percent of adults and 6 percent of children have a food allergy. Food intolerance doesn’t involve the immune system but can cause some of the same gastrointestinal symptoms as food allergy. For example, lactose intolerance, where people don’t hav
