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Currently, it is believed that proteins derived from the digestion of gluten, (the part of grains toxic to people with celiac disease) including gliadin, are able to pass into the wall of the intestine. Once inside the intestinal wall (in the submucosa), an enzyme known as tissue transglutaminase, or IgA-tTG, changes the shape of the small gliadin proteins. The modified gliadin is then processed by antigen presenting cells. These cells are designed to present many different kinds of substances to the immune cells. The immune system then decides what is harmful and what is not.
After processing by the antigen presenting cell, the gliadin in its new shape is able to activate the immune system through binding to T cells, causing inflammation and the release of chemicals that can affect the entire body. Only people that have the HLA-DQ2 or HLA-DQ8 genes have T cells that bind gluten proteins (mostly gliadin). The ability of these cells to bind to gluten-derived peptides is inherited. It seems to be the main reason why some people get celiac disease (CD) and others do not.
The small intestine is lined with finger-like projections called villi. The villi are needed to produce digestive enzymes and aid in the absorption of nutrients. When a patient with CD eats gluten, these villi become shorter or flattened, with less ability to make enzymes. The shorter villi decrease the surface area available to absorb nutrients. The overall result of eating gluten is decreased digestion and nutrient absorption. This can lead to malnutrition and symptoms such as diarrhea and fatigue.
The villi are not permanently damaged in CD, but it may take years for the villi to fully recover in older people. The intestine is able to regenerate every three days, but the amount of time it takes for the villi to return to normal varies from person to person. In general, the intestine is expected to heal over a period of weeks to months on a gluten-free diet.
Once CD is diagnosed, a life long GFD is the only available treatment. Continuous exposure to gluten in people with CD can lead to severe small intestinal damage (complete loss of villi). Untreated CD can also lead to malabsorption, bone loss, nutritional deficiencies, and a small but real risk of gastrointestinal cancers such as small intestinal lymphoma. This damage can be reversed or improved substantially in the majority of people who follow the GFD closely.
This is not an unusual complaint. Once CD is confirmed through biopsy and IgA-tTG testing, the IgA-tTG levels should trend down by half-fold in 3-6 months. Persistently high IgA-tTG means that the CD is not well controlled. The most common cause is accidental exposure to gluten. Meeting with a dietitian skilled in celiac disease is very important and useful.
A minority of patients with CD will have continued high IgA-tTG levels despite being on a strict GFD. This is called refractory celiac and is often treated with medication in addition to the GFD. Visit Non-Responsive Celiac Disease Level 2 under Medical Management on www.celiacnow.org. While diary and fructose could cause symptoms that mimic “uncontrolled celiac”, they do not typically cause elevation of the IgA-tTG.
Celiac disease (CD) is an autoimmune condition that leads to changes in the immune system in genetically predisposed people upon exposure to gluten. This condition causes intestinal inflammation and gastrointestinal symptoms.
Studies have looked at determining the safe levels of gluten exposure. The lowest amount of daily gluten that causes damage to the celiac intestinal mucosa over time (the gluten threshold) is 10 to 50 mg per day (a 25-g slice of wheat bread contains approximately 1.6 g of gluten). The Codex Alimentarius regulation and the Food and Drug Administration both endorse a maximum gluten contamination of <20 ppm (parts per million) in a gluten-free product. Under twenty ppm is considered a safe threshold even for patients who eat large amounts of wheat/gluten substitutes.
Once the amount of gluten intake crosses this threshold, the severity of gastrointestinal symptoms and intestinal damage is independent of the quantity of gluten intake. The chain of inflammatory events that are activated once the threshold is passed is independent of the amount of gluten. This phenomenon is not completely understood.
While this may seem reasonable, it is not correct as ppm are not additive in this way. If this was the case you could make the same argument for a bite of a food vs. a serving of that same food when obviously there will be different total amounts of gluten depending on how much you eat. 20 ppm was chosen based on what is both safe with easily achievable amounts of food and easily measurable. A food with 20ppm of gluten is about .002% gluten or 20mg/kg. Given the usual threshold of 50mg per day of gluten you need to eat ~2.5 kg or 5.5 pounds of that food in a day to be a problem. This would be equivalent to about 4 or 5 loaves of bread! It doesn’t matter what the food is as long as it has the same ppm rating.
The answer to this question likely depends on quantity of gluten exposure. There is no firm data to support inhalation as a means of gluten exposure. However, it is possible for some gluten to enter the gastrointestinal tract if there was a significant enough inhalation of gluten, for example, a bakery worker. In this case, one would expect that gluten would be inhaled, stick to mucous membranes and then be swallowed. The best evidence would likely come from a period of time away from the work site to see if symptoms improved in the short term.
If there is concern, a few simple steps may be taken to prevent exposure. Whenever possible, avoid touching any surfaces that may have gluten-containing flour on them. For those who are preparing gluten-containing food for family or friends, wash your hands promptly after touching gluten or surfaces with gluten. Avoid putting your hands in or near your mouth to avoid ingestion of gluten. If desired, to help prevent inhalation, wear a mask while working with gluten-containing flour. This would only be necessary if there were a large amount of gluten/flour in the air. It is unlikely, however, that there would be a significant exposure if the duration of time in this environment was less than a few hours.
Important Note: a bakery worker (in a gluten containing facility) with celiac disease faces exposure to gluten from both inhalation and frequent contact with surfaces containing flour.
Reference: Dr. John Zone. Personal email correspondence; Oct 2013.
CD is treated with a strict, lifelong, gluten-free diet (GFD). Once gluten is removed from the diet, healing and regeneration of the intestine begins. Young children respond very well to the diet, and usually heal completely within a year. Adults generally take longer, and some may never fully heal on the GFD, even though their symptoms usually resolve. At this time, there are no medications or treatments other than the GFD for CD. Visit How Celiac Disease is Treated Level 1-2 on www.celiacnow.org.
One way to remember the treatment of celiac disease is by the acronym C.E.L.I.A.C.:
Consultation with a skilled dietitian
Education about celiac disease
Lifelong adherence to a gluten-free diet
Identification and treatment of nutritional deficiencies
Access to an advocacy group
Continuous long-term follow-up by a multidisciplinary team.(NIH consensus statement, 2004)
Visit Nutritional Consults under Nutrition and the Gluten-Free Diet on www.celiacnow.org to learn about how a skilled dietitian in celiac disease can help make your adjustment to the gluten-free lifestyle much easier.
Undiagnosed CD may have negative effects on pregnancy. Undiagnosed CD is associated with an increased risk of growth retardation, low birth weight, preterm birth, miscarriage, and cesarean section. However, once patients are diagnosed with CD and are on a gluten-free diet (GFD), they do not experience any negative outcomes associated with pregnancy. This is most likely the result of compliance with the GFD. In general, women with CD tend to be older at the age of their first childbirth than women without CD.
It is important that pregnant women who are gluten-free maintain a healthy diet in order to have a healthy pregnancy. Your diet should include adequate calories per day based on your weight and trimester. It is important that these calories come from healthy, vitamin and mineral-rich fruits and vegetables, lean sources of proteins, gluten-free grains, and healthy fats. Eat foods rich in vitamins A, C, and D, calcium, iron, and folic acid, as these nutrients are extremely important for your health during pregnancy, as well as the health of your baby. Stay well hydrated. Choose foods that are high in omega-3 and omega-6 fatty acids, such as oily fish (salmon, sardines) and nuts. You will want to take the equivalent of 300mg/day of DHA (an essential fatty acid). You should take a gluten-free prenatal vitamin supplement, as well as calcium (as needed) and vitamin D supplementation after consultation with your doctor. Pregnant women with CD should see a dietitian for further instructions on how to maintain a healthy diet during pregnancy.
Once diagnosed with celiac disease (CD), it is important to maintain life-long follow up with a doctor regarding your condition. This follow-up is especially important since there are several manifestations of CD that are not related to the gastrointestinal tract. Visit FAQ- Associated Conditions on www.celiacnow.org.
Specifically, you should see your primary care physician (PCP) for any initial problems you may have. Your PCP or another specialist may make or suspect the initial diagnosis of CD. However, a referral to a gastroenterologist skilled in the diagnosis and management of CD is usually needed to confirm the initial diagnosis and plan further management including:
Counseling regarding the test results and screening of family members
Evaluation for associated disorders
Arranging for consultation(s) with a skilled celiac dietitian
Initial education regarding dietary treatment of CD
Evaluation for nutritional deficiencies
Initiation of nutritional supplements, as needed
Monitoring your response to the gluten-free diet
Adjustment of diet, as well as nutritional supplements, according to clinical and immunologic response
If an associated disorder is discovered, such as thyroid disease, you may be referred to another specialized doctor for management of the problem. In the case of CD, an endocrinologist may be seen for thyroid problems, diabetes, or management of bone health.
The Celiac Center at Beth Israel Deaconess Medical Center has a listing of clinicians skilled in the management of celiac disease. These individuals will aid in the diagnosis of the disease if you or your PCP suspects CD and will also provide long- term specialized care for people already diagnosed with CD. Please visit Our Celiac Center Team on www.celiacnow.org home page. Also visit What to Expect from your Gastroenterologist’s Visit under Medical Management.
Revision Date: 10-8-13 Authors: Clinicians of the Celiac Center, Javier Villafuerte MD, Rohini Vanga MD, with assistance from Annie Peer Editors: Melinda Dennis, MS, RD, LDN and Daniel Leffler MD, MS.