GLUTEN-FREE DIET: DEFINITION AND APPLICATIONS

Abstract

The treatment for celiac disease is a gluten-free (GF)diet for life.1 This means strict avoidance of foods andbeverages that contain wheat, rye, barley and triticale (across between wheat and rye). A GF diet is also requiredfor management of other disorders of gluten intoleranceincluding dermatitis herpetiformis and non-celiac glutensensitivity. Gluten is a generic term applied to proteinsin wheat (gliadin), barley (hordein) and rye (secalin).Patients with poorly treated celiac disease are at risk ofseveral complications including nutritional deficiencies(e.g., osteoporosis), development of other autoimmunedisorders and malignancies such as intestinallymphoma.A GF diet is complex, both for understandingand its application in everyday living. Wheat is not onlyubiquitous in our diet, wheat flour (atta) is the mostabundant and affordable staple food. Flours derivedfrom naturally gluten-free grains like rice, corn,sorghum and millet provide good alternates but thesegrains are more expensive and cross contamination withwheat during milling process is almost universal. A GFdiet is significantly more expensive as patients oftenhave to rely on packaged food and is also sociallyrestrictive especially for eating out and travelling.Because of these complexities, it is essential thatpatients requiring a GF diet consult a registered dieticianskilled in this area.2 Such dietetic services are notalways readily available. In countries like Pakistanwhere awareness of GF diet and regulation for foodlabelling is limited, patients face far greater challenges.Ideally, a GF diet should have zero gluten.However, the reality is that there is some backgroundcontamination with gluten-containing grains in manyfood products. There is limited research investigatingthe threshold of gluten acceptability in a GF diet. Anelegant study by Catassi et al demonstrated that as littleas 50 mg of gluten if ingested daily for a few monthscan lead to villous injury.3 This is a very tiny quantityand amounts to about 1/70th of a slice of toast. Thesafety threshold of gluten ingestion will also depend onthe total amount of food consumed per day. Suchresearch studies are difficult to perform as they requirerepeated invasive procedures (small intestinal biopsies)to look for early villous changes.In the past, there had been controversy aboutthe definition of GF diet. In Europe, gluten content of upto 200 ppm was acceptable in a GF diet whereas inNorth America the limit was set at 20 ppm. (Parts permillion is equivalent to milligrams per kilogram, i.e., 20ppm implies 20 mg of gluten per Kg of food).Furthermore, wheat starch was permissible in a GF dietin Europe but not in North America. A consensus on aninternational definition of GF diet has been reached onlyrecently. Codex Alimentarius Commission is aninternational body of the Food and AgricultureOrganization of the United Nations (FAO UN) and theWorld Health Organization (WHO) responsible forsetting standards for regulating foods allergens. In July2008, the Codex Committee on Nutrition and Foods forSpecial Dietary Uses revised its standard for foods to beconsidered ‘gluten-free’ for international trade. Thehighlights of this Standard include the following:1. Gluten-free foods do not contain wheat, rye,barley, oats or their crossbred varieties and thegluten level does not exceed 20 ppm (20 mg/Kg) intotal, based on the food as sold to the consumer.and/or2. Gluten-free foods may contain one or moreingredients from wheat, rye, barley, oats or theircrossbred varieties which have been speciallyprocessed to remove gluten and the gluten level doesnot exceed 20 ppm (20 mg/Kg) in total, based on thefood as sold to the consumer.3. The allowance of pure, uncontaminated oats may bedetermined at the national level.4. Foods specially processed to reduce gluten content toa level between 20–100 ppm (20–100 mg/Kg) basedon the food as sold or distributed to the consumermust not be labelled gluten-free. Labelling terms forsuch products (e.g., low gluten, reduced gluten) anddecisions for marketing may be determined at thenational level, but must indicate the true nature of thefood.Pure and uncontaminated oats in limitedquantities are safe for consumption by most patientswith celiac disease.5 However, because of frequentcontamination of the commercially available oats withgluten-containing grains, they are included in the abovedefinition of GF diet. This standardised definition ofgluten-free is now being applied internationally and willcreate uniformity for trade.Understanding the definition of GF diet isimportant not only for patients and health careprofessionals but also for food manufacturers andgovernment agencies regulating food safety. It is thefood manufacturer’s responsibility to ensure that thegluten content of the product labelled gluten-free doesnot exceed the allowed limit of 20 ppm. Gluten in wheatJ Ayub Med Coll Abbottabad 2011;23(1)2 http://www.ayubmed.edu.pk/JAMC/23-1/Mohsin.pdfis a mixture of gliadin and glutenin proteins, eachcomposed of several sub-fractions. Gluten analysis is,therefore, a complex procedure and not routinelyavailable. The currently recommended test for glutenquantification is the R5 ELISA and few laboratories areequipped to perform the analysis accurately.A food manufacturer in Pakistan has recentlybeen selling whole wheat flour (atta) by marketing it as‘gluten-free’. Gluten in wheat is what gives its flour thebinding capacity and currently there is no technologyavailable to remove all gluten from wheat and stillmaintain its characteristic as flour. The manufacturer’sclaim in this case is clearly misleading and willjeopardise the health of patients on GF diet. Due to alack of good understanding of a GF diet, it is easy forpatients (and physicians) to succumb to such claims. Inaddition, because of poor health safety regulations, thegovernment authorities have not taken any measures toaddress this serious problem.In summary, patients, health careprofessionals, food industry and government regulatoryagencies all need to learn about GF diet. Patients mustbe vigilant about label reading. Any claims of a productbeing gluten-free should be critically evaluated withappropriate testing. The government should enact strictfood labelling legislation and scrutinise anymanufacturer claiming to make GF products to ensurethe health of patients on a GF diet.