What is celiac disease?
Celiac disease is a genetically based autoimmune condition in which the body attacks itself as a form of self-defense.

This chronic immunologic response is triggered by gluten -- a portion of the protein present in grains, including wheat, barley, rye, and spelt. This list extends to other grains that are ancient relatives of wheat, such as Kamut, triticale, emmer, and einkorn. The immunologic response to gluten can result in malabsorption of nutrients, leading to a variety of serious health complications.

The intolerance to gluten is permanent and cannot be outgrown even if diagnosed in early childhood. Once considered a rare childhood disease that would eventually be outgrown, celiac disease now affects mostly adults.

A very recent study from the Mayo Clinic confirmed that the prevalence of celiac disease has increased more than fourfold in the past 50 years. Globally, epidemiologists estimate that celiac disease may affect 0.5 per cent to one per cent of the population, although many cases remain undiagnosed.

The only truly effective treatment is adopting a gluten-free diet and restoring nutrient deficiencies with a balanced diet and nutritional supplements.

Genetically based autoimmune conditions
Our immune system provides us with an army of antibodies to fight off antigens (viruses, bacteria, and toxins) that we come into contact with in the air, our food, and our water. The body's first line of defense is the lining of the intestinal tract, which is equipped with white blood cells that produce antibodies called IgA (immunoglobulin A) specific to the gastrointestinal tract's immune system.

When gluten comes into contact with the intestinal lining, the immune system revs up, causing the release of different types of IgA antibodies that instigate an inflammatory process. This process leads to deterioration of the intestinal villi.

Gluten protein fraction
Gluten is a component of the protein found in the endosperm portion of the wheat kernel. Its large size makes it hard to digest. It passes through the stomach, withstands the strength of the churning action, the powerful stomach acid, and protein-digesting enzymes to make its way intact into the duodenum, where it is perceived as toxic by the body's immune system.

It is unclear how gluten gets into the mucosal wall, but it may be related to breaks in the mucosal barrier caused by an inflammation involving what is referred to as a leaky gut.


What causes celiac disease?
Individuals with celiac disease have the genetic makeup to develop it, but this potential is triggered by environmental and immunologic factors.

Genetic factors
This disease is inherited; it runs in the family. A first-degree sibling has a 40 per cent chance of also inheriting the disease. In the general population, there is a seven per cent to 20 per cent chance that any member of the family of an individual affected with celiac disease may also carry the same genetic makeup.

The two specific genes that have been recognized so far in celiac disease are part of the HLA class. The proteins found on white blood cells that are encoded by genes HLA-DQ2 and HLA-DQ8 are primed to interact with gluten. About 95 per cent of individuals with celiac disease have the HLA-DQ2 gene, while only five per cent have the HLA-DQ8.

Lately, however, it has become clear that the genetic makeup of celiac disease is not limited to these two types of genes. In fact, to date, at least 13 additional candidate genes have been identified as contributing to celiac disease.

Screening
More than 50 per cent of patients with celiac disease have a family member with undiagnosed disease. Children, siblings, and parents of people diagnosed with celiac disease should be tested because they carry a high risk of being carriers of DQ2 and DQ8.

Screening for celiac disease includes blood tests and a small intestine tissue biopsy. Genetic testing may be useful in some cases.

Environmental factors
The environmental trigger in the genetically susceptible person is gluten, the protein fraction found in wheat, barley, rye, spelt, and Kamut. These proteins are called gliadins in wheat, hordeins in barley, and secalins in rye.

In the past, the avenin protein in oats was also included in the list. However, oats are known to be more closely related to rice and a more distant genetic relative of wheat, barley, and rye.

Currently there is concern over cross-contamination of commercially available oats with gluten-containing grains during harvesting, transportation, and milling.

Immunologic factors
In a person with an HLA-DQ2 or HLA-DQ8 genetic makeup who is exposed to gluten in the environment, there need only be a switch, such as a gastrointestinal infection, pregnancy, or surgical procedure, to turn on the immunologic response that produces the symptoms of celiac disease.


Antibodies and antigens
When gluten comes into contact with the intestinal lining, the immune system revs up, causing the release of different types of IgA antibodies that instigate an inflammatory process. This process leads to deterioration of the intestinal villi. Because these antibodies are specific for their interaction with gluten, blood tests measuring their concentration in the bloodstream are very accurate.

Symptoms of celiac disease
Celiac disease can surface in many different ways. Almost every system of your body may be affected. This very wide spectrum of symptoms is also a reason why celiac disease can take a long time to diagnose. Not only do symptoms range in severity, but they affect everyone differently.

Some individuals become violently ill the minute they ingest a piece of bread or a bite of a wheat cracker. Others may have long-standing iron deficiency anemia that they keep treating with iron supplements without any resolution.

Celiac disease can range from severe to mild in its symptoms. Those who are very symptomatic will seek ongoing medical care. Those with very few symptoms may find the diagnosis an annoyance.

Gluten sensitivity versus celiac disease
While in celiac disease gluten triggers an autoimmune reaction causing damage to the intestinal lining, in gluten sensitivity it causes only abdominal symptoms.

Individuals with gluten sensitivity will experience bloating, constipation, and cramping, but there will be no underlying damage to the intestines, nor will they suffer from any complications such as nutrient deficiencies or metabolic, hormonal, and neurological disorders. For these people, simply taking gluten out of the diet will make them feel better.

Atypical celiac disease
Sometimes celiac disease may affect only the proximal (or uppermost) part of the small intestine instead of reaching far down and causing many of the classical gastrointestinal symptoms. In this case, affected individuals develop only single nutrient deficiencies, such as iron or calcium deficiency, which can lead to various conditions, such as osteopenia, osteoporosis, and anemia.

Some of these patients may also have mild gastrointestinal symptoms, such as bloating, constipation, and indigestion, which usually get diagnosed as irritable bowel syndrome.

Associated conditions
Although celiac disease tends to occur on its own, it is associated with a number of other conditions.

If you are suffering from any of the following conditions, you are at a higher risk of having celiac disease and should consider being tested:

• Diabetes (type 1 insulin-dependent diabetes mellitus)
• Thyroid disease
• Osteoporosis
• Autoimmune liver disease
• Down syndrome
• Turner syndrome
• Selective IgA deficiency
• Sjögren's syndrome (dry-mouth syndrome)
• Cardiomyopathy
• Addison's disease
• T-cell lymphoma

Malabsorption symptoms
If celiac disease spreads downward in the small intestine, absorption of fat-soluble vitamins, such as A, D, E, and K, is affected.

• Vitamin A deficiency: visual and reproductive problems
• Vitamin D deficiency: rickets (in children), osteopenia, and osteoporosis
• Vitamin E deficiency: neurological symptoms, such as "pins and needles" sensations in hands and feet or unsteadiness of gait
• Vitamin K deficiency: easy bruising and bleeding

Nutrient deficiencies typically develop with undiagnosed celiac disease and can result in serious complications.

• Iron deficiency: anemia, fatigue, weakness
• Calcium deficiency: osteopenia, osteoporosis
• Folate deficiency: anemia, fatigue, weakness
• Vitamin B12 deficiency: in severe cases, may lead to fatigue and weakness