To eat or not to eat gluten: Your DNA may tell

For most people, gluten is synonymous with wheat. Gluten is indeed the primary storage protein in wheat. However, similar proteins (also known as gluten) occur in rye, barley, and oats [1].

Wheat kernels consist of 8 - 15% protein, of which gluten is about 85 - 90% [1]. The properties of gluten make it an important ingredient for successful baking. It is found in almost all cakes, biscuits, pastries, and pasta [1].

Any processed food may also contain gluten since it aids in improving texture, flavor, and retaining moisture. It may thus be added to many foods that don’t necessarily contain wheat [1].

In recent years, gluten has been getting an increasingly negative connotation. It is considered healthy to decrease consumption thereof. This is mainly due to some of the components of this protein being difficult to digest [1]. These protein components are what give rise to gluten intolerance.

Coeliac disease is probably the best-known form of gluten intolerance. The two terms are frequently used as synonyms. Gluten intolerance, however, also includes two other conditions.

The other two conditions are non-coeliac gluten sensitivity and wheat allergy [2, 3]. In other words, one may be allergic to wheat or be sensitive to gluten without suffering from coeliac disease [1].

The following symptoms may be present with all conditions related to gluten, Chrohn’s disease, and irritable bowel syndrome [3]:

• Nausea
• Constipation
• Bloating
• uneven bowel habits
• abdominal discomfort
• abdominal pain
• diarrhea

Coeliac disease is an autoimmune condition that affects people with a genetic predisposition [3, 4]. It is marked by specific immune antibodies [3]. About 1% of Western and American citizens suffer from this disease [1, 5]. Sub-Saharan Africa’s prevalence is lower [5].

Like coeliac disease, wheat allergy also involves an immune response when wheat products are consumed [3]. It is, however, not an auto-immune disease. People with gluten sensitivity do not experience an immune response. In other words, there is no inflammation involved.

Symptoms of coeliac disease may be broad, but may, additional to the above, include [4, 5]:

• Weight-loss
• Malabsorption
• Poor growth
• Short stature
• Anemia and iron deficiency
• Delayed puberty
• Decreased bone density
• Dermatitis

If you have coeliac disease, gluten intake may have severe and damaging effects. The gluten proteins that are not digested may activate an immune response [1]. This immune response involves inflammation which will cause damages the lining of the intestines [4].

Over time, the intestinal damage may lead to your intestines losing their ability to absorb nutrients [6]. This damage could, of course, have serious effects in the long term.

Unfortunately, coeliac disease symptoms differ significantly from one person to the next [5, 7]. It is also likely to suffer from the disease without you knowing it. 21% of patients may have no symptoms at all [5]. The absence of symptoms does, however, not mean the intestines don’t get damaged.

A 100% certain diagnosis of coeliac disease requires a biopsy of the intestines together with antibody testing. [5, 6]. The presence of the IgA-TG2 antibody has proven to provide the most sensitive and specific blood (serum) marker [6]. People with coeliac disease can handle different amounts of gluten [1]. For this reason, although oats do contain some gluten, it may be tolerated well by some [4, 7].

The primary and only truly effective treatment for coeliac disease is to follow a life-long gluten-free diet [8]. There is no cure otherwise. Adopting a gluten-free diet should ideally only be done under guidance. This is to ensure intake of all the needed dietary nutrients [7, 9].

Gluten and wheat should not be removed from the diet blindly. People that do not suffer from gluten intolerance should also not remove gluten from their diets [9,10]. There are no apparent benefits of a gluten-free diet for individuals that can handle gluten [9].

Wheat is an important substrate for healthy gut bacteria [1]. The gut bacteria can thus be negatively affected by a gluten-free diet [7]. Micronutrient and fiber deficiencies may develop more easily on a gluten-free diet [9, 10]. Micronutrient deficiencies often found include calcium, iron, folate, and several B vitamins [10].

Coeliac disease is highly hereditary and more common in women than men [5]. The HLA DNA gene is needed for developing coeliac disease [1, 4, 5, 6]. Most people with coeliac disease possess the HLA-DQ2 gene. If they do not have it, they will have the HLA-DQ82 gene [11].

If you have neither of the HLA genes, you won’t get coeliac disease [5, 6, 11]. Luckily, having these genes also does not guarantee that you will definitely have the disease [4, 11]. Other genes have also been found to be involved [11, 12].

Before you remove all gluten and wheat from your diet, first make sure that it is needed. By having your genes tested, you can find out whether you have a high risk for gluten intolerance. This way, you can determine the need for a gluten-free diet without having to wait for severe symptoms to appear.

References:

[1] Biesiekierski, J. R. (2017). What is gluten? Journal of Gastroenterology and Hepatology (Australia), 32, 78–81. https://doi.org/10.1111/jgh.13703

[2] Cabanillas, B. (2020). Gluten-related disorders: Celiac disease, wheat allergy, and nonceliac gluten sensitivity. Critical Reviews in Food Science and Nutrition, 60(15), 2606–2621. https://doi.org/10.1080/10408398.2019.1651689

[3] Roszkowska, A., Pawlicka, M., Mroczek, A., Bałabuszek, K., & Nieradko-Iwanicka, B. (2019). Non-celiac gluten sensitivity: A review. Medicina (Lithuania), 55(6), 1–19. https://doi.org/10.3390/medicina55060222

[4] Tye-Din, J. A., Galipeau, H. J., & Agardh, D. (2018). Celiac disease: A review of current concepts in pathogenesis, prevention, and novel therapies. Frontiers in Pediatrics, 6(November), 1–19. https://doi.org/10.3389/fped.2018.00350

[5] Caio, G., Volta, U., Sapone, A., Leffler, D. A., De Giorgio, R., Catassi, C., & Fasano, A. (2019). Celiac disease: A comprehensive current review. BMC Medicine, 17(1), 1–20. https://doi.org/10.1186/s12916-019-1380-z

[6] Al-Toma, A., Volta, U., Auricchio, R., Castillejo, G., Sanders, D. S., Cellier, C., Mulder, C. J., & Lundin, K. E. A. (2019). European Society for the Study of Coeliac Disease (ESsCD) guideline for coeliac disease and other gluten-related disorders. United European Gastroenterology Journal, 7(5), 583–613. https://doi.org/10.1177/2050640619844125

[7] Sharma, N., Bhatia, S., Chunduri, V., Kaur, S., Sharma, S., Kapoor, P., Kumari, A., & Garg, M. (2020). Pathogenesis of Celiac Disease and Other Gluten Related Disorders in Wheat and Strategies for Mitigating Them. Frontiers in Nutrition, 7(February), 1–26. https://doi.org/10.3389/fnut.2020.00006

[8] Melini, V., & Melini, F. (2019). Gluten-free diet: Gaps and needs for a healthier diet. Nutrients, 11(1). https://doi.org/10.3390/nu11010170

[9] Diez-Sampedro, A., Olenick, M., Maltseva, T., & Flowers, M. (2019). A Gluten-Free Diet, Not an Appropriate Choice without a Medical Diagnosis. Journal of Nutrition and Metabolism, 2019. https://doi.org/10.1155/2019/2438934

[10] Niland, B., & Cash, B. D. (2018). Health benefits and adverse effects of a gluten-free diet in non-celiac disease patients. Gastroenterology and Hepatology, 14(2), 82–91.

[11] Van Heel, D. A., Franke, L., Hunt, K. A., Gwilliam, R., Zhernakova, A., Inouye, M., Wapenaar, M. C., Barnardo, M. C. N. M., Bethel, G., Holmes, G. K. T., Feighery, C., Jewell, D., Kelleher, D., Kumar, P., Travis, S., Walters, J. R. F., Sanders, D. S., Howdle, P., Swift, J., … Wijmenga, C. (2007). A genome-wide association study for celiac disease identifies risk variants in the region harboring

[12] Dubois, P. C. A., Trynka, G., Franke, L., Hunt, K. A., Romanos, J., Curtotti, A., Zhernakova, A., Heap, G. A. R., Ádány, R., Aromaa, A., Bardella, M. T., Van Den Berg, L. H., Bockett, N. A., De La Concha, E. G., Dema, B., Fehrmann, R. S. N., Fernández-Arquero, M., Fiatal, S., Grandone, E., … Van Heel, D. A. (2010). Multiple common variants for celiac disease influencing immune gene expression. Nature Genetics, 42(4), 295–302. https://doi.org/10.1038/ng.543