What is coeliac disease?
Coeliac disease (also known as gluten-sensitive enteropathy or coeliac sprue) is a condition of the small intestine. Gluten, a substance found in wheat, barley and rye, reacts with the small bowel, causing damage by activating the immune system to attack the delicate lining of the bowel, which is responsible for absorbing nutrients and vitamins.
The condition is often diagnosed in childhood after weaning when cereals are introduced into the diet, although it can be diagnosed at any age.
The symptoms can be subtle, and you may feel unwell for no reason for some time before the diagnosis is made.
If left untreated, coeliac disease can lead to anemia, bone disease and, rarely, some forms of cancer. The most important treatment is avoiding all food that contains gluten. This usually results in improvement, or even disappearance, of the damage to the lining of the bowel. However, the damage will recur if gluten is re-introduced into the diet.
What are the risks?
Until recently, it was thought that coeliac disease only occurs in about 1 in 1500 people. It is now thought to be more common. More accurate diagnosis through simple blood tests has shown that the condition affects up to 1 in 300 people in the United Kingdom, Europe and the USA.
It is more common in some areas of the world, particularly on the west coast of Ireland, where 1 in every 100 people are thought to have coeliac disease.
Coeliac disease is a common condition, and can affect anyone at any age. It was thought to be more common in men, but probably occurs equally in men and women.
Coeliac disease is sometimes associated with other conditions. People with insulin-dependent diabetes, thyroid problems and ulcerative colitis, have an increased chance of developing coeliac disease.
What causes coeliac disease?
Gluten is a mixture of two proteins, gliadin and glutenin. When mixed with water it becomes sticky and so forms the familiar texture of dough made from wheat and rye flour. When gluten comes into contact with the lining of the small bowel, a reaction occurs, where the immune system mistakenly attacks the lining of the bowel as if it was a ‘foreign’ organism.
The small bowel has ‘villi’, which are tiny finger-like projections, visible under the microscope. They provide a large surface area, over which we absorb nutrients, such as vitamins, folic acid, iron and calcium.
In coeliac disease these are attacked by the immune system, and are eventually destroyed. This results in nutrients in food going down the gut without being absorbed (malabsorption), leading to vitamin and mineral deficiencies, anemia and thin bones (osteoporosis).
A definite risk factor to developing coeliac disease is a history of the condition in your family. Coeliac disease occurs in people who are genetically prone to it – it ‘runs’ in families. If you have a parent, sibling or child with coeliac disease, you have a 10 per cent chance of also developing it.
If you have an identical twin with coeliac disease, your chances are increased to more than 70 per cent.
What are the symptoms?
Coeliac disease has many and varied symptoms, and adult symptoms are different from those of children.
In childhood the symptoms do not appear until gluten-containing foods are introduced into the diet. First symptoms usually include becoming irritable and miserable, with a poor appetite and failure to gain weight. Stools (bowel motions) can become pale, bulky and smell nasty. Some children start with vomiting and diarrhea, so they are often given the wrong diagnosis of ‘gastroenteritis’. The stomach may become swollen, and the muscles of the arms and legs become wasted and thin.
In adults the symptoms may be similar, including weight loss with pale, offensive diarrhea, or constipation and abdominal bloating with ‘wind’.
Half of adults with coeliac disease do not have any symptoms from the bowel.
They approach their doctor because of extreme tiredness, psychological problems like depression, bone pain and sometimes even fractures (due to thinning of the bones), ulcers in the mouth or a blistering, itchy skin rash mostly on the elbows and knees (called dermatitis herpetiformis).
Some women with coeliac disease have difficulty getting pregnant, and may be diagnosed because of this. Recurrent miscarriage (spontaneous loss of a pregnancy) is sometimes associated with coeliac disease. Some women are diagnosed during pregnancy because their bowel cannot absorb enough iron and vitamins to keep up with the demand of being pregnant, making them severely anemic.
Babies who are small for their age in the womb (intrauterine growth retardation) are more frequently born to mothers with coeliac disease.
There are other rare conditions, which although found in the general population, occur more frequently in people with coeliac disease. These conditions usually require referral to a hospital specialist. They include autoimmune diseases (where the immune system inadvertently attacks the body) such as thyroid disease, insulin dependent diabetes and a condition that affects the liver called primary biliary cirrhosis.
In one neurology (brain and nerve disease) clinic, several patients who had difficulty walking and co-ordinating (ataxia) for no apparent reason were tested for coeliac antibodies in the blood. A significant number of these patients were found to have coeliac disease, although many of them did not have any gut symptoms.
How is coeliac disease diagnosed?
Your GP may ask you for a history of your symptoms. This may include questions about the frequency and color of your bowel motions, but there is no need to feel embarrassed about this. They may also want to know whether you have lost weight or whether you have symptoms of anemia (tiredness, exhaustion, pallor).
The doctor may examine your abdomen, or look for the blistering rash on your skin, and check for mouth ulcers.
Blood tests are usually the first investigation. Your doctor will check for anemia, testing the levels of iron, folic acid and calcium in your blood. Another blood test detects antibodies (part of the immune system) commonly, but not always, found in coeliac disease.
Several different types of antibodies are associated with coeliac disease but the most specific is called ‘anti-endomysial’ antibody. If this is present in the blood, then you are very likely to have coeliac disease.
However, an endoscopy test – with a biopsy of the small bowel lining – is required for a definite diagnosis to be made. Your doctor should arrange this test at the Endoscopy Unit at your local hospital. You can usually choose to have the test under general anesthetic (put to sleep) or have a local anesthetic (numbing the throat with a spray).
Then a tiny camera on the end of a thin flexible tube is put into the mouth and is guided down the oesophagus (gullet) into the stomach and then the small bowel. A small piece of the lining of the bowel can be removed (called a biopsy) – you will not feel any discomfort.
The whole procedure will take about 10 minutes. The biopsy specimen will be sent to the laboratory where it can be examined under a microscope to check on the size and shape of the villi. This will usually confirm the diagnosis. It is usual to have this test repeated after several months on a gluten-free diet, to check that the lining has recovered.
What else could it be?
Diarrhea and weight loss can be due to several other causes. One other cause is a bowel infection, such as caused by parasites called Giardia lamblia and Strongyloides.
If your symptoms started after a tropical holiday, one of these infections may be to blame.
Other rare causes of malabsorption include overgrowth of the small intestine with other bacteria, lactose intolerance, Whipple’s disease or intestinal lymphoma.
What treatment is available?
Although coeliac disease is not preventable, sticking to a gluten-free diet can reverse damage to the small intestine. This requires considerable discipline. Gluten occurs in bread, biscuits, cakes and pastries, pasta, breakfast cereals and is also used in some manufactured soups and sauces.
Gluten is also ‘hidden’ in some foods such as crisps and similar snacks, as well as chips in restaurants. Cooking oil (or mixed vegetable oil) can contain wheat-germ oil, so use sunflower or olive oil instead. Malt vinegar, soy sauce, mustard and mayonnaise contain gluten. Beer and whisky are made from grain containing gluten, but other alcoholic drinks, such as wine or cider are gluten-free.
Of course, many foods do not contain gluten, including all fruits, salads and vegetables, rice, maize, sweetcorn, nuts, potatoes, red meat, chicken, fish, eggs and dairy products.
It is probably best to avoid oats as they may contain a small amount of gluten. Oats have generally been shown not to upset people with coeliac disease. However, most oats are milled and stored in the same mills as wheat and are probably contaminated with gluten.
- There are excellent books available on gluten-sensitivity, including general guides and recipe books.
- Some medicines contain gluten, so you must check with your doctor or pharmacist.
What can your doctor do?
Gluten-free foods are available with or without a prescription from your doctor or pharmacy. These include gluten-free flour, breads, biscuits and pasta. These should be used as a substitute for the normal gluten-containing varieties. Your GP should also refer you for a consultation with a dietitian, who can give you diet sheets and advice.
Another important aspect of treatment is replacing vitamins and minerals. You may need iron tablets, folic acid supplements (especially when pregnant or planning to get pregnant) and calcium.
Very severe coeliac disease, which does not get better on a gluten-free diet, may need tablets that ‘damp down’ the immune system, such as steroid tablets, but this is very rare.
There are no known severe risks of treatment. However, gluten-free food does tend to be low in fiber and can cause constipation in some people. To counteract this, take plenty of fruit and vegetables. If the problem persists, try rice bran or a laxative called Fybogel, which is available with or without a prescription from your pharmacy.
What are the consequences of no treatment?
Not taking a gluten-free diet will cause the symptoms to persist, including diarrhea, weight loss and anemia.
What is the likely outcome?
Complications of coeliac disease are rare. They include infertility in women, difficulties during pregnancy, autoimmune diseases (thyroid disease, diabetes and some types of liver disease), thinning of the bones (osteoporosis). There is a slightly increased risk of developing bowel cancer.
However, a gluten-free diet reduces all these complications, as well as associated conditions such as dermatitis herpetiformis and mouth ulcers.
Studies have shown that sticking to a gluten-free diet for five years or more reduces the risk of all cancers associated with coeliac disease to that of the general population.
A gluten-free diet should enable the lining of the bowel to return to normal in most people. So the disease can be ‘curable’, but only by avoiding foods that contain gluten. You can enjoy a good quality of life without symptoms or long-term complications.