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Celiac disease, also known as sprue, celiac sprue, nontropical sprue, and gluten-sensitive enteropathy, is a life-long autoimmune disease in which the body’s reaction to gluten causes damage to the intestines that results in poor absorption of nutrients.
Absorption of most nutrients occurs in the small intestine. The intestine is lined with microscopic, hairlike projections called villi, and it is through these villi that nutrients are absorbed. Villi project into the
intestine and provide an increased the surface area for absorption. Damage to the villi results in inadequate absorption, especially of vitamins, minerals, and fats.
Celiac disease is an autoimmune disease. Whenever immune system cells in the body sense the presence of foreign material, they produce proteins called antibodies that act to disable the foreign material. In an autoimmune disease, the body treats some of its own cells as foreign and attacks them. Celiac disease is also classified as a malabsorption disease because the cells that are damaged by the body’s immune system are cells of the villi lining the small intestine. When these cells are damaged, the villi flatten out, decreasing the surface area available for absorption. Nutrients are not properly absorbed, and vitamin and mineral deficiencies often develop.
The symptoms of celiac disease were describe as early as 1888, but it was not until the 1950s that physicians began to understand what caused the disease. A Dutch pediatrician, W. K. Dicke, was the first person to make the connection between the consumption of foods containing wheat and symptoms of celiac disease. Today researchers know that the problem substance is gluten found in wheat, rye, and barley, and products such as four, bread, and pasta made from these grains. The role of oats and oat products in celiac disease remains controversial.
Celiac disease is most common among people of Northern European ancestry and is uncommon to rare among people of African or Asian ancestry. Initially celiac disease was thought to be uncommon in the United States, but recent improvements in genetic testing and disease awareness have changed that picture. Experts now believe that in the United States and other areas of the world settled primarily by Europeans (e.g. Australia), about 1 of every 133 people has celiac disease. The disease has an inherited component, and the rate increases to 1 of every 22 people who are blood relatives of a parent, sibling, or child with the disease. In about 70% of identical twins, if one has celiac disease, the other also has it. Celiac disease is also more common among people with other genetically-related autoimmune diseases such as systemic lupus erythematosus, type 1 diabetes (juvenile diabetes), rheumatoid arthritis, and autoimmune thyroid disease.
People of any age can be diagnosed with celiac disease. However, there are two common peaks for diagnosis, one between 8–15 months, which is shortly after infants usually begin eating wheat products, and another between 30–40 years in adults.
Researchers have traced the genetic component of celiac disease to a cluster of genes on chromosome six. Multiple genes are involved, which may account for the variation in symptoms and inheritability of the disease. Often, symptoms of the disease develop after a serious infection, physical trauma, pregnancy, or surgery. Researchers do not know why stress on the body appears to trigger symptoms.
Symptoms of celiac disease are varied. Some people have the disease (as diagnosed by samples that show damage to the small intestine), but they show no symptoms. Others go along for years with annoying or intermittent symptoms, and some, especially children, show severe symptoms of malnutrition that stunt growth despite eating a healthy diet. Symptoms are similar to those of other, more common, digestive diseases Often celiac disease is initially misdiagnosed.
Common symptoms of celiac fall into two categories, those primarily related to the immediate problems of digesting food and those that result mainly from long-term deficiencies in vitamins and minerals.
Symptoms primarily related to immediate difficulties in digestion include:
- chronic diarrhea
- foul-smelling grayish stools. These result from inability to properly digest fats
- gas, abdominal bloating
- abdominal cramps
- weight loss
Other symptoms that develop because of vitamin and mineral deficiencies can include:
- iron deficiency anemia, low red blood cell count
- joint pain, muscle pain, muscle cramps
- osteoporosis (inadequate calcium absorption)
- tingling in the legs from nerve damage
- bleeding disorders (inadequate vitamin K)
- missed menstrual periods
- infertility (women), frequent miscarriages
- failure to thrive in infants
- delayed mental and physical growth in children
Other symptoms include:
- irritability and behavioral changes especially in children
- pale sores inside the mouth
- dermatitis herpetiformis, an itchy skin rash that usually appears on the trunk, buttocks, neck, and scalp.
Celiac disease can be difficult to diagnose because its symptoms are similar to those of so many other diseases. Often it is initially misdiagnosed as irritable bowel syndrome or Crohn’s disease Stool examination, blood tests, and lactose (milk sugar) tolerance tests are often done when the patient first complains of symptoms, but there are two definitive tests for celiac disease.
The immune system of people with celiac disease produces higher than normal levels of certain antibodies. Blood tests can detect abnormal levels of these antibodies. If blood tests are positive, a small bowel endoscopy with biopsies is done. Endoscopies are usually performed in a doctor’s office or an outpatient clinic while the patient is under light sedation. In this procedure, the physician inserts a tube called an endoscope down the patient’s throat, through the patient’s stomach and into the upper part of the small intestine. A tiny camera at the end of the endoscope allows the doctor to see if there is damage to villi. During this procedure, the doctor also removes small tissue samples (biopsies) from the intestinal lining in order to look for cell damage under the microscope. Presence of a specific type of damage is a positive diagnosis for celiac disease.
When individuals fail to improve on a gluten-free diet, it is sometimes because they are unintentionally consuming sources of hidden gluten. A few people on truly gluten-free diets do not improve. They can be treated with corticosteroid drugs to reduce inflammation, but this does not heal the intestine. Clinical trials concerning treatment of celiac disease are underway. Patients interested in participating in a clinical trial at no cost can find a list of trials currently enrolling volunteers at <http://www.clinicaltrials.gov>
Individuals newly diagnosed with celiac disease need counseling from a nutritionist and help in meal planning from a dietitian. Two issues need to be addressed. First, what is safe to eat, and second, how to get the right balance of nutrients in a gluten-free diet. Complicating matters, damage to the intestines may make some people lactose intolerant, so that they either cannot eat or must limit dairy products in their diet.
Many cookbooks are available to help people on a gluten-free diet. Home cooks must learn to substitute ingredients such as cornstarch and rice flour for wheat flour in their foods. An increasing number of gluten-free foods are available commercially. However, these often cost more than their gluten-containing counterparts. Below are listed just a few foods people with celiac disease can safely eat.
- plain fruits and vegetables
- plain meat that has not been breaded, coated, or mixed with fillers
- rice (all types)
- cornmeal, cornstarch, and products made of corn, such as corn tortillas
- dried beans and peas
Other foods must be avoided. Individuals with celiac disease must also avoid cross-contamination with these foods. For example, they should not cut gluten-free bread using a knife that has cut regular wheat bread unless the knife has been thoroughly washed. Even small amounts of gluten can cause damage to the intestine. Some of the foods people with celiac disease must avoid are listed below.
- wheat flours including durum flour, enriched flour, graham flour, semolina flour, and white flour
- wheat germ, wheat starch, wheat bran, cracked wheat
- products made with the above mentioned wheat products such as pasta, bread, cakes, cookies
- barley, barley flour, and products made with barley
- rye, rye flour, and products made with rye
- triticale and other wheat hybrids
Learning how to read food labels is very important to people who must avoid gluten. However, this may become easier in the future. In January 2007, the United States Food and Drug Administration (FDA) published preliminary regulations s for foods that could be labeled “gluten free.” Labeling will be voluntary. The FDA hopes to have these rules take effect by August 2008. This will make it easier for shoppers who must avoid gluten to find products they can safely eat. Meanwhile, people with celiac disease must be alert to “hidden” sources of gluten that often serve as binders or thickeners in commercially prepared foods. Some of these non-obvious sources of gluten that may appear on food labels are listed below.
- starch (type unspecified)
- modified food starch
- hydrolyzed vegetable protein (HVP)
- hydrolyzed plant protein (HPP)
- texturized vegetable protein (TVP)
- excipients (ingredients used in medications that do not have medicinal value, such as coatings of tablets. Consult a pharmacist or physician about whether before taking drugs, vitamins, etc.)
Some brands of commercially prepared french fries, potato chips, hot dogs, meatballs, gravy mixes, soups, soy sauce, and candy contain these hidden sources of gluten. Others are gluten-free. A nutritionist and dietitian can help people with celiac disease learn to read labels accurately to distinguish that foods are safe for them.
The intestines of people with celiac disease who go on a gluten-free diet heal. In children the healing usually takes 3–6 months. In adults healing can take 2 years. The intestinal villi remain intact and function properly so long as the diet remains free of gluten, but the disease is never cured.
People who are not diagnosed or who do not stay on a gluten-free diet face increased chances of developing cancer of the intestine. They may also develop osteoporosis because of poor calcium absorption. Other vitamin and mineral deficiencies may contribute to a multitude of health problems. Untreated pregnant women have higher than normal rates of miscarriage and babies born with birth defects, especially neural tube defects, which arise from inadequate amounts of folic acid. Untreated children may have stunted mental and physical growth.
Celiac disease is a genetic autoimmune disorder that cannot be prevented. Once diagnosed, the only way to prevent symptoms and complications is to follow a strictly gluten-free diet.
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Tish Davidson, A.M.