Part 3: Practical advice on how to follow a gluten-free diet

Parts 1 and Part 2 of this series discussed the details of gluten sensitivity disorders and important scientific evidence to consider when deciding whether a gluten-free diet is right for you. In Part 3, we will provide a quick-reference guide for foods that do and do not contain gluten as well as a short discussion on how to interpret “gluten-free” food labels.

Gluten-containing and gluten-free foods
All products that contain wheat, rye, or barley contain gluten (see Table 1). It is important to read the label for all processed foods. Often, lunch meats, sauces, soups, condiments, candies, snacks, and other foods can appear gluten-free but contain wheat-based ingredients and/or are processed in facilities that also process wheat, rye, or barley and can therefore be contaminated.

Table 1. Common grains and flours that do and do not contain gluten
Contain gluten Does not contain gluten*
Wheat (including spelt, semolina, durum, wheat starch, wheat bran, wheat germ)
Triticale (hybrid of wheat and rye)
Malt (extract, flavoring, syrup, vinegar)
Wheat-based products (e.g. couscous, orzo, most beer)
Hydrolyzed plant or vegetable protein
Rice (all kinds including glutinous rice)
Nut flours
Beans and bean flours (e.g. fava, garbanzo)
Pea and pea flour
Tapioca (also known as cassava)
Root crops

*These grains and flours do not inherently contain gluten. However, these products may be contaminated with gluten during processing. Look for a “gluten-free” label to be sure.
†Oats do not contain gluten but contain avenin, a protein that contains a peptide similar to a peptide in gluten that can be offensive to celiac patients (Ellis & Ciclitira, 2008).

References for Table 1:
(Niewinski, 2008; Saturni, Ferretti, & Bacchetti, 2010; Schwarzenberg & Brunzell, 2002)

What does a “gluten-free” label or certification symbol mean?
The Codex Alimentarius Commission of the World Health Organization of the United Nations provides international gluten-free food standards for manufacturers. If a product contains less than 20 ppm (20 mg gluten/kg of food) gluten it is considered “gluten-free”. In August 2013 the United States adopted this limit so that any product with the “gluten-free” label has 20 ppm gluten or less. Manufacturers have one year to comply with the new regulation, so starting in August 2014 products will be “misbranded” and manufacturers will be punished if the gluten-free label is inaccurate.

To put this “20 ppm” amount into perspective, consumption of 7 × 1 oz. servings of “gluten-free” grains that contain exactly 20 ppm in one day will give you 4 mg of gluten. In a prospective, double-blind, placebo-controlled study, Catassi et al. determined that celiac patients should consume less than 50 mg gluten per day to avoid intestinal damage (Catassi et al., 2007).

There are currently four independent companies that certify products as gluten-free: The Celiac Sprue Association (CSA), the Gluten Intolerance Group (GIG), the National Foundation for Celiac Awareness (NFCA), and Quality Assurance International (QAI, a division of the National Science Foundation, NSF). These different agencies have different requirements for certification, though all are stricter than the FDA (see Table 2).

Table 2. Gluten-free certification requirements

Gluten Limit 20 ppm 5 ppm 10 ppm 10 ppm 10 ppm
Wheat, rye, barley, and oat ingredients allowed if gluten is removed prior to use Yes Not currently, but this is a future goal Yes, all ingredients must have less than 10 ppm gluten before use Yes Yes
Regular product testing required No Annually Annually Annually Annually
Symbol No symbol, but the words “gluten-free”, “no gluten”, “free of gluten”, or “without gluten” CSA gluten free symbol GIG gluten free symbol NFCA gluten free symbol QIA/NSF gluten free symbol

References for Table 2:

(Celiac Support Association, 2013; Food and Drug Administration, 2013; Gluten Intolerance Group, 2014; National Foundation for Celiac Awareness, 2014; Quality Assurance International, 2011; Thompson, 2011)


Catassi, C., Fabiani, E., Iacono, G., D’Agate, C., Francavilla, R., Biagi, F., … Fasano, A. (2007). A prospective, double-blind, placebo-controlled trial to establish a safe gluten threshold for patients with celiac disease. The American Journal of Clinical Nutrition, 85(1), 160–166.

Celiac Support Association. (2013). CSA Recognition Seal Program. Retrieved June 15, 2014, from

Ellis, H. J., & Ciclitira, P. J. (2008). Should coeliac sufferers be allowed their oats? European Journal of Gastroenterology & Hepatology, 20(6), 492–493. doi:10.1097/MEG.0b013e3282f465b0

Food and Drug Administration. (2013). Questions and answers: Gluten-free food labeling final rule. Retrieved from

Gluten Intolerance Group. (2014). FAQ: Gluten-free Certification Organziation (GFCO). Retrieved June 15, 2014, from

National Foundation for Celiac Awareness. (2014). Gluten-free certificaiton program. Retrieved June 15, 2014, from

Niewinski, M. M. (2008). Advances in celiac disease and gluten-free diet. Journal of the American Dietetic Association, 108(4), 661–672. doi:10.1016/j.jada.2008.01.011

Quality Assurance International. (2011). Gluten-Free Program. Retrieved June 15, 2014, from

Saturni, L., Ferretti, G., & Bacchetti, T. (2010). The gluten-free diet: Safety and nutritional quality. Nutrients, 2(1), 16–34. doi:10.3390/nu2010016

Schwarzenberg, S. J., & Brunzell, C. (2002). Type 1 Diabetes and Celiac Disease: Overview and Medical Nutrition Therapy. Diabetes Spectrum, 15(3), 197–201. doi:10.2337/diaspect.15.3.197

Thompson, T. (2011). Gluten-free Certification. Retrieved from
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