What is gluten?

     Celiac disease and the idea of gluten-free diets were merely a blip on the radar 20 years ago.  However, in the United States and across the world more individuals are being diagnosed with celiac disease, and more consumers are embracing the idea of a gluten-free diet (GFD)(1).  Researching a topic is always more interesting when a personal interest regarding the topic exists.  My mother discovered 4 years ago that she was gluten sensitive, and I have been learning bits and pieces about gluten ever since.  As a student of nutrition and an employee of a gluten-free food company, I felt it was my duty to learn as much as I could about gluten.  The following is a brief summary of my findings based upon current scientific research regarding gluten.

            Gluten is a structural protein that is found in wheat, rye, and barley.  Oats do not contain gluten, but most commercially produced oats contain trace amounts of gluten unless otherwise noted on the package.  Human exposure to gluten containing grains took rise around 10,000 years ago as agriculture began to develop.  Gluten is widely used in food processing, and it has been long prized for the desirable characteristics it lends to breads and doughs.  In the United States, gluten is most commonly found in bread, baked goods, pasta, cereal, and snack foods (1).

            Gluten has become increasingly popular in the media, and those following GFDs have also steadily increased.  In 2010, global sales of gluten-free products totaled nearly $2.5 billion dollars (1).  In addition to this, the occurrence of undiagnosed celiac disease in the United States is approximately 4 times greater than 50 years ago (2).   It is estimated that around 1% of the population in the United States could have celiac disease (3), and 1% of the population would equal more than 3 million people (4).  In addition to developing scientific research, the increased number of those with celiac disease and gluten sensitivity/intolerance makes gluten something worth investigating.  

            Celiac disease has long been the health issue related to gluten.  Celiac disease is an inflammatory disorder of the small intestine that occurs from the ingestion of gluten containing foods (5).  Celiac disease is heavily genetic and may also be dependent on other environmental factors.  Celiac disease is typically diagnosed by blood tests that detect the presence of antibodies to gliadin (a component of gluten).  If an individual tests positive, a biopsy of the small intestine is normally taken to give a definitive diagnosis of having celiac disease.  Those most susceptible to celiac disease are Caucasians, especially those with northern European ancestry (5).  Women are also twice as likely as men to be diagnosed with celiac disease (6).

            If gastrointestinal distress exists, a physician will often suggest an exclusion diet.  In an exclusion diet, a food that is normally eaten is removed from the diet to see if symptoms improve with its removal.  This is commonly done with gluten and dairy at the same time until symptoms subside, and then one or the other is added back in to the diet to see if it is the culprit.  Celiac disease is dangerous because the ingestion of gluten causes damage to villi in the small intestine.  The villi are like little fingers that reach out to grab nutrients, and their presence helps increase the absorptive area of the intestine.  Untreated celiac disease will damage the villi (causing the surface to flatten), and individuals may suffer from serious malabsorption and malnutrition (5).

 

An example of celiac disease related intestine damage (5)

            In the past, you were either celiac or you were not, and the idea of gluten sensitivity or intolerance was not widely accepted.  Some people have similar gastrointestinal symptoms as those with celiac disease, but they do not test positive for celiac disease.  A recent study fed individuals suffering from irritable bowel syndrome (IBS) a gluten-free diet.  Those consuming a gluten-free diet experienced less gastrointestinal problems compared to those who continued to consume gluten.  This study shows that some people who are suffering from bowel problems may feel better by removing gluten from their diet.  The mechanism of how removing gluten from the diet is beneficial for those without celiac disease is not completely understood, but this opens the door to the possibility that multiple types and levels of gluten intolerance may exist (7).

            Recently, gluten has begun to be associated with more than just celiac disease.  Gluten increases the permeability of the gut, and it appears that this increases the chance of autoimmune disorders in gluten-sensitive individuals (8).  Autoimmune diseases that may be linked to gluten include type 1 diabetes and thyroid disease (9).  Another gluten-related health issue is dermatitis herpetiformis, a skin rash that is resolved by eating a GFD.  Gluten ataxia, a fairly uncommon neurological disorder, is where the cerebellum is damaged by gluten anti-bodies.  This leads to motor skill issues, and removing gluten from the diet typically stops the progression of the condition but does not repair what has been damaged.  Individuals who have celiac disease are at greater risk for these autoimmune diseases and gluten-related health problems (9).  Recently, the media has tried to pinpoint gluten as a possible cause of autism, but there currently are not any studies supporting this claim (5).

            Although gluten may seem like the bad guy, one must remember that only a portion of the general public is negatively affected by gluten.  Increasing scientific research is tying gluten to other health issues, but the science is far from condemning gluten altogether.  This information is provided to give a general overview of gluten and to show why some may be consuming a gluten-free diet.  However, one should consider getting tested if they have a family history of celiac disease or gluten intolerance.  Many are still unsure about gluten, but more scientific research that is being done will offer insight into how it may or may not be affecting our health.

References

1.  Sapone A, Bai JC, Ciacci C, et al. Spectrum of gluten-related disorders: Consensus on new nomenclature and classification. BMC Med. 2012:10(13);1-12.

2.  Rubio-Tapia A, Kyle RA, Kaplan EL, et al. Increased prevalence and mortality in undiagnosed celiac disease. Gastroenterol. 2009:137(1);88-93. 

3.  Questions and answers on the gluten-free labeling proposed rule. US Food and Drug Administration. http://www.fda.gov/food/labelingnutrition/foodallergenslabeling/

     guidancecomplianceregulatoryinformation/ucm111487.htm. May 14, 2012.  Accessed November 23, 2012.

4.  U.S. & world population clocks. United States Census Bureau. http://www.census.gov/main/www/popclock.html. December 3, 2012.  Accessed December 3, 2012.

5.  Di Sabatino A, Corazza GR. Coeliac disease. Lancet. 2009:373(9673);1480-1493.

6.  Megiorni F, Mora B, Bonamico M, et al. HLF-DQ and susceptibility to celiac disease: Evidence for gender differences and parent-of-origin effects. Am J Gastroenterol. 2008:103;997-1003.

7.  Biesiekierski JR, Sci BA, Newnham ED, et al. Gluten causes gastrointestinal symptoms in subjects without celiac disease: A double-blind randomized placebo-controlled trial. Am J Gastroenterol. 2011:Advance online publication.

8.  Visser J, Rozing J, Sapone A, Lammers K, Fasano A. Tight junctions, intestinal permeability, and autoimmunity. NY Acad Sci. 2009:1165;195-205.

9.  Troncone R, Jabri B. Coeliac disease and gluten sensitivity. J Int Med. 2011:269;582-590.