Gluten is a protein in wheat, barley, and rye and is associated with two dietary conditions, celiac disease and non-celiac gluten sensitivity (NCGS).

Celiac Disease

Celiac disease (CD) is an autoimmune genetic disorder affecting approximately 1% of people worldwide, although it may be underreported. It is identified with blood tests that detect specific antibodies, namely anti-tissue transglutaminase (tTG) IgA, with a confirmatory small intestine biopsy.

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Tissue-transglutaminase is a necessary enzyme in humans that links and strengthens tissue proteins in the body, including proteins comprising the small intestine. Transglutaminase, called “meat glue” in food processing, is a common processed meat additive that binds meat particles together improving texture. Although not conclusive, a connection between this food additive and a worsening of the CD response is proposed.

The autoimmune response in CD is an attack of ingested gluten and the intestinal cells lining the small intestine, called enterocytes. Enterocytes collectively form projections called villi, which increase small intestine nutrient absorption. When these cells are damaged, nutrient absorption is compromised.

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CD symptoms may include chronic diarrhea, constipation, abdominal pain, bloating, unexplained weight loss, fatigue, anemia, dermatitis herpetiformis (skin rash), osteoporosis, and neurological issues.

CD is a permanent condition requiring life-long gluten restriction. Detectable improvements in villi regeneration can occur after six months with complete recovery often taking beyond two years.

Non-Celiac Gluten Sensitivity

Non-celiac gluten sensitivity (NCGS) is estimated to affect approximately 10% of people in the US.

Rather than activating humans’ more evolved, adaptive, immune response as in CD, NCGS triggers the more general, primitive, innate inflammatory response. It does not result in as much intestinal damage as celiac disease and does not specifically damage the villi enterocytes, but may contribute to gut permeability.

The exact causes of NCGS remain unclear and may actually not involve a response to gluten itself. One line of evidence suggests the innate immune response is to certain non-gluten wheat proteins called ATIs that happen to exist in the gluten containing wheat, barley, and rye. ATIs serve as plant defenses against insect pests.

ATI proteins include inhibitors of the enzyme amylase, which breaks down starchy polysaccharide carbohydrates into their simpler disaccharide form. They also include inhibitors of the enzyme trypsin, which breaks down protein into smaller chains of amino acids. These inhibitors are collectively called amylase-trypsin inhibitors, or ATIs.

Another line of evidence suggests that since wheat contains fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAPs), a gut microbial response to these compounds, rather than gluten, may cause excessive gas, bloating, and abdominal discomfort.

Symptoms may also include fatigue, brain fog, headaches, joint pain, skin rash (different from celiac-related dermatitis herpetiformis), without damage or shrinkage of intestinal villi.

NCGS is diagnosed by ruling out CD from blood tests and improved symptoms after a temporary, up to six-week, FODMAP and ATI restriction found in wheat, barley, and rye.

Conclusion

While CD and NCGS share many common symptoms, their underlying causes and treatments differ. Those diagnosed with CD must permanently and completely eliminate gluten containing foods.

However, those with NCGS should only temporarily restrict minimally processed forms of wheat, barley, rye and high FODMAP foods as these foods, when tolerance rebuilds, can improve gut health. Highly processed and ultra-processed forms of these foods can and perhaps should be restricted indefinitely.

Consulting with a registered dietitian can help those with either CD or NCGS navigate the food environment to identify and develop healthy, delicious, and sustainable alternatives to trigger foods and manage healing.

About the Author

Patrick Traynor, PHD, MPH, RD, CPT is a registered dietitian with an insurance-based practice, MNT Scientific, LLC in South Lake Tahoe, CA, Minden, NV, & Ashland, OR. In office or video appointments can be requested online at MNTScientific.com or by calling (530)429-7363. Inquiries can be directed to info@mntscientific.com.