Gluten in diet and medications
Introduction
Gluten is a protein found in wheat, barley, and rye. Gluten-free grains include potato, corn, rice, etc. Some people experience gastrointestinal (GI) symptoms (e.g., abdominal pain, diarrhea, gas) after ingesting gluten. People may avoid gluten because of a wheat allergy, gluten intolerance, celiac disease, or for a variety of other reasons (e.g., weight loss, boost mood or energy, reduce pain, eat “healthier”).
Gluten intolerance, allergy or celiac disease
Gluten intolerance is sometimes confused with celiac disease, or thought of as a food allergy. Even though avoiding certain foods is a management strategy for all three, these conditions are different.
- Gluten intolerance involves the digestive system. Patients may experience GI symptoms following gluten ingestion. Patients choose to limit gluten intake to minimize GI symptoms.
- Allergies occur when the immune system overreacts to an allergen (e.g., eggs, peanuts, wheat) exposure causing potentially life-threatening symptoms (e.g., anaphylaxis). There is no such thing as a gluten allergy. However, patients with a wheat allergy should avoid foods and topical products containing wheat (or gluten from wheat) that trigger symptoms. It is not necessary to avoid gluten from other sources (i.e., barley, rye).
- Celiac disease is an autoimmune disorder "see note 1". Gluten ingestion leads to GI symptoms (similar to gluten intolerance), but more importantly can lead to malabsorption and damage to the small intestine. A lifelong, gluten-free diet is the primary treatment for patients with celiac disease.
How much gluten is too much for patients with celiac disease?
- Patients with celiac disease should avoid ingesting gluten and maintain a gluten-free diet.
- Even on a gluten-free diet, patients probably ingest between 5 and 50 mg of gluten per day, because of unknown or trace sources of gluten or contamination. In fact, foods that contain less than 20 parts per million (ppm), or about 0.5 mg, are considered gluten-free foods.
- The amount of gluten required to cause symptoms and damage will vary from patient to patient. However, limited evidence suggests that patients may be able to consume up to 50 mg of gluten per day without significantly damaging the small intestine. Patients that are more sensitive to gluten may have symptoms with just 10 mg per day.
Identifying gluten in medications
Most medications do not contain gluten, but labels don’t always say “gluten-free”. Medications usually contain gluten-free starches (e.g., corn, potato, rice, tapioca). Patients who do well on a gluten-free diet are unlikely to have problems with the very small amount of gluten that may be found in medications (usually < 0.5 mg/dose). Consider looking for gluten in medications for patients who continue to have symptoms, despite a strict gluten-free diet. It is unnecessary to look for gluten in topical products. Gluten is not absorbed topically. It is unnecessary to identify gluten in intravenous products. Gluten is not used in intravenous medications. In addition, intravenous products are not usually ingested.
Focus on solid oral medications when looking for sources of gluten. It is very unlikely you will find gluten in liquid medications, even liquid medications containing sugar alcohols. Sugar alcohols are considered safe (e.g., mannitol, xylitol, sorbitol) for patients with celiac disease. However, sugar alcohols are Fermentable Oligosaccharides, Disaccharides, Monosaccharides, And Polyols (FODMAPs). FODMAPs are not absorbed well and can also cause GI symptoms (for anyone sensitive to FODMAPs, not specifically patients with celiac disease or gluten intolerance).
Don’t look for the word “gluten”. Sources of gluten in oral medications may include flour, caramel coloring, dextrins, dextrates, dextrimaltose, or other starches (e.g., modified, pregelatinized, sodium starch glycolate). If the source of the starch is wheat (or isn’t stated), the product may contain gluten. Medications don’t have starches from barley or rye.
Tips for avoiding gluten in diet
It can be a challenge to avoid gluten in food. But you're not doomed to boring foods. You can find plenty of healthy gluten-free foods that tempt the taste buds "see table 1".
| Table (1). Tips for Avoiding Gluten in Your Diet | |
|---|---|
| General Rules | |
|
|
| ALLOWED Grains/Flours | Rice, corn (maize), soy, potato, tapioca, beans, garfava, sorghum, quinoa, millet, buckwheat, arrowroot, amaranth, teff, Montina, flax, and nut flours.
|
| NOT ALLOWED IN ANY FORM | Wheat (einkorn, durum, faro, graham, kamut, semolina, spelt), rye, barley, and triticale. Frequently overlooked foods that may contain gluten and need to be verified:
|
Helpful resources
Use the Product information as a first-step to identify potential sources of gluten. U.S. product labeling can be accessed at Daily Med (dailymed.nlm.nih.gov/dailymed). Canadian product labeling is available at the Health Canada Drug Product Database (https://health-products.canada.ca/dpd-bdpp/index-eng.jsp). Manufacturers may also be a source of information, if the source of the starch (e.g., “wheat” flour) is not specified in the product information. Be prepared with specific information (i.e., ndc number, lot number). Other online resources, "see note 2".
Online resources may also be helpful...
- Pillbox: pillbox.nlm.nih.gov (may provide information on the source of the starch).
- Gluten Free Drugs: glutenfreedrugs.com.
- FDA: www.fda.gov/drugs/ensuring-safe-use-medicine/medications-and-gluten.
- Beyond Celiac: www.beyondceliac.org/living-with-celiac-disease/gluten-in-medication/.
- Canadian Celiac Association: https://www.celiac.ca.
References
- American Academy of Allergy Asthma & Immunology. Gluten intolerance definition. Available at: https://www.aaaai.org/conditions-and-treatments/conditions-dictionary/gluten-intolerance.
- Beyond Celiac. Gluten in medications. Available at: https://www.beyondceliac.org/living-with-celiac-disease/gluten-in-medication.
- FDA. Gluten in drug products and associated labeling recommendations. Guidance for industry (draft guidance). December 2017. Available at: https://www.fda.gov/media/116958/download.
- Parrish CR. Medications and celiac disease – tips from a pharmacist. January 2007. Available at: https://celiac.org/main/wp-content/uploads/2009/11/MedicationsandCeliacDisease.pdf.
- Catassi C, Fabiani E, Iacono G, et al. A prospective, double-blind, placebo-controlled trial to establish a safe gluten threshold for patients with celiac disease. Am J Clin Nutr 2007;85:160-6.
- Mangione RA. Caring for patients with celiac disease: the role of the pharmacist. J Am Pharm Assoc 2008;48:e125-39.
- American College of Allergy, Asthma & Immunology. Wheat allergy. Available at: https://acaai.org/allergies/types/food-allergies/types-food-allergy/wheat-gluten-allergy.
- Gluten Free Drugs. Updated March 19, 2020. Available at: https://glutenfreedrugs.com.
- Boyd, C. Is there gluten in your medicine? December 22, 2011. Available at: https://www.glutenfreeandmore.com/issues/is-there-gluten-in-your-medicine.
- FDA. Medications and gluten. Dec 17, 2017. https://www.fda.gov/drugs/ensuring-safe-use-medicine/medications-and-gluten.
- Canadian Food Inspection Agency. Gluten-free claims. January 15, 2019. Available at: http://www.inspection.gc.ca/food/requirements/labelling/industry/allergens-and-gluten
- FDA. Gluten and food labeling. July 16, 2018. Available at: https://www.fda.gov/food/nutrition-education-resources-and-materials/gluten-and-food-labeling.
- Pulido O, Zarkadas M, Dubois S, et al. Clinical features and symptom recovery on a gluten-free diet in Canadian adults with celiac disease. Can J Gastroenterol 2013;27:449-53.
- University of Virginia Nutrition. Low FODMAP diet. December 2016. Available at: https://med.virginia.edu/ginutrition/wp-content/uploads/sites/199/2018/05/LowFODMAPDiet12.16.pdf.