Food allergies and intolerances

Four of the most common food intolerances include lactose, wheat, egg and peanut intolerance. Many people also have intolerant reactions to food additives, such as MSG (monosodium glutamate) or food dyes. However, these substances have not yet been scientifically proven as a cause of intolerance and, therefore, not officially classified as such. The following is an explanation of the above listed food intolerances:

• Lactose intolerance: This is the most common form of adverse reaction to cow's milk. Lactose, which is a milk sugar, must be broken down by an enzyme called lactase before it can be absorbed by the body. In affected adults and children, lactase is not produced in sufficient quantities for the milk sugar to be broken down. The result is that it passes through the body undigested, causing stomach pain, bloating and diarrhoea. However, people with lactose intolerance can often eat small quantities of dairy products without experiencing any symptoms. Additionally, dairy products such as yoghurt, hard cheeses and lactose-reduced milk can be tolerated in most cases, because the form of lactose in these products does not seem to affect people as severely.
• Wheat intolerance: The bowel affliction coeliac disease is the main form of wheat intolerance. It affects around one in 300 people in the UK, who are susceptible to gluten, a protein present in wheat, rye, barley, and possibly oats. Gluten can damage the lining of the gut, which leads to a reduced capacity to absorb nutrients from foods and results in diarrhoea and malnutrition. In the general population, coeliac disease affects two women to every man. This discrepancy may be affected by nutritional stresses such as pregnancy or blood loss. It is also believed that coeliac disease may be caused by introducing foods containing gluten to children, who are weaning. Generally, young babies' digestive systems are not mature enough to process large proteins. These are, therefore, treated as foreign particles and removed from the body. People with coeliac disease need to follow a strict, lifelong, gluten-free diet. The UK Coeliac Society (01494 437 278) publishes an updated list of gluten free foods, as do most major supermarkets.
• Egg intolerance: This type of reaction occurs within minutes of eating an egg. Symptoms include, rashes and swelling on the face and around the mouth. People with an egg intolerance need to avoid all foods containing egg white or egg yolk, from all sources, including chicken, goose and duck. Many food products, like cakes, bread, mayonnaise and custard, contain egg or egg proteins, so be vigilant about checking ingredients labels before you buy.