Gluten intolerance is also called Coeliac disease or gluten sensitivity. It's an auto-immune disease, which means the body's immune system attacks itself. The type of reaction it causes is different to a food allergy - it doesn't cause anaphylaxis. Many people with coeliac disease don't realise they have it.

When people with coeliac disease eat foods containing gluten, it damages the lining of the small intestine, which stops the body from absorbing nutrients. This can lead to diarrhoea, weight loss and eventually malnutrition.

Foods to avoid

Gluten is a protein found in wheat and also in a number of other cereals including rye and barley. So, if you have coeliac disease you need to avoid foods made from these cereals, including most types of bread, pasta, pizza, pastry and cakes.

Wheat ingredients are used in many foods, such as some sausages and burgers, and many sauces. Foods in batter or breadcrumbs aren't suitable for people with coeliac disease either. If you have coeliac disease, always check the ingredients on the foods you buy. You will also need to avoid some alcoholic drinks made from barley, such as beer and lager.

Since November 2005, food labelling rules require pre-packed food sold in the UK, and the rest of the European Union, to show clearly on the label if it contains cereals containing gluten, including wheat, rye, barley and oats (or if one of its ingredients contains these). Bear in mind that there could still be foods on the shelves that were produced before this date.

Rice, potatoes and corn don't contain gluten, so these are OK to eat. You can also buy special products that are suitable for people with coeliac disease, such as gluten-free pasta and bread.

Oats contain a protein that is similar to gluten, but not exactly the same. It's also possible for small amounts of other cereals, such as wheat, to get into oat products when the crop is growing, or being harvested or transported. Research has shown that some people with coeliac disease can't tolerate oats or oat products. At the moment, medical experts don't have enough evidence to decide whether all people with coeliac disease should avoid oats.

If you have coeliac disease you will probably be advised to avoid oats, as well as wheat, rye and barley, especially when you are first diagnosed. You should discuss whether to start eating oats again with your health professional because oats may not be suitable for some people with coeliac disease.

It's important to understand that products labelled 'wheat free' aren't the same as those labelled 'gluten free'.

Wheat-free products may contain other cereals, such as rye or barley, so these might not be suitable for someone with coeliac disease (unless they are also labelled 'gluten free').

Gluten-free products won't contain gluten, but they may still contain other proteins found in wheat (albumins, globulins and starch granule proteins). So these might not be suitable for people who are intolerant or allergic to wheat.

Coeliac UK, a charity to support people with gluten intolerance, works with manufacturers to produce a regularly updated list of foods that don't contain gluten.