By David Dunaief, M.D.
A quick trip to the grocery store or a restaurant will confirm what you already know: gluten-free is a “thing.” Pizza, pasta, bread, and even breadcrumb-encrusted products have been reformulated, and everyday products, like frozen vegetables, have been relabeled with splashy language promising “gluten-free.” The marketers are on board: gluten-free diets are hot.
“Gluten-free” is not necessarily synonymous with healthy. Still, we keep hearing how more people feel better without gluten. Is this a placebo effect? What is myth and what is reality in terms of gluten? In this article I will try to distill what we know about gluten and gluten-free diets, who may benefit and who may not.
Gluten is a plant protein found mainly in wheat, rye and barley. While more popular recently, going gluten-free is not a fad, since we know that patients who suffer from celiac disease, an autoimmune disease, benefit tremendously when gluten is removed (1). In fact, it is the main treatment.
But what about people who don’t have celiac disease? There seems to be a spectrum of physiological reaction to gluten, from intolerance to gluten (sensitivity) to gluten tolerance (insensitivity). Obviously, celiac disease is the extreme of intolerance, but even these patients may be asymptomatic.
Then, there is nonceliac gluten sensitivity (NCGS), referring to those in the middle portion of the spectrum (2). The prevalence of NCGS is half that of celiac disease, according to the NHANES data from 2009-2010 (3). However, many disagree with this assessment, indicating that it is much more prevalent and that its incidence is likely to rise (4). The term was not even coined until 2011.
Celiac disease vs. gluten sensitivity
Both may present intestinal symptoms, such as bloating, gas, cramping and diarrhea, as well as extraintestinal (outside the gut) symptoms, including gait ataxia (gait disturbance), malaise, fatigue and attention deficit disorder (5). Surprisingly, they both may have the same results with serological (blood) tests.
The first line of testing includes anti-gliadin antibodies and tissue transglutaminase. These measure a reaction to gluten; however, they don’t have to be positive for there to be a reaction to gluten. HLA–DQ phenotype testing is the second line of testing and is more specific for celiac disease.
What is unique to celiac disease is a histological change in the small intestine, with atrophy of the villi (small fingerlike projections) contributing to gut permeability, what might be called “leaky gut.” Biopsy of the small intestine is the most definitive way to diagnose celiac disease. Though the research has mainly focused on celiac disease, there is some evidence that shows NCGS has potential validity, especially in irritable bowel syndrome.
Before we look at the studies, what does it mean when a food says it’s “gluten-free”? The FDA requires that “gluten-free” labeled foods have no more than 20 parts per million of gluten (6). Effective October 13, 2020, new FDA guidelines go into effect for proving fermented foods, such as sauerkraut and yogurt, and hydrolyzed ingredients found in many packaged products meet the same criteria.
Irritable bowel syndrome
Irritable bowel syndrome (IBS) is a nebulous disease diagnosed through exclusion, and the treatments are not obvious. That is why the results from a 34-patient, randomized controlled trial, the gold standard of studies, showing that a gluten-free diet significantly improved symptoms in IBS patients, is so important (7). Patients were given a muffin and bread on a daily basis.
Of course, one group was given gluten-free products and the other given products with gluten, though the texture and taste were identical. In six weeks, many of those who were gluten-free saw the pain associated with bloating and gas mostly resolve; they had significant improvement in stool composition, such that they were not suffering from diarrhea, and their fatigue diminished. In one week, those in the gluten group were in substantially more discomfort than those in the gluten-free group.
As part of a well-written editorial in Medscape by David Johnson, M.D., a professor of gastroenterology, questioned whether this beneficial effect from the IBS trial was due to gluten withdrawal or to withdrawal of fermentable sugars because of the elimination of some grains themselves (8). In other words, gluten may be just one part of the picture. He believes that nonceliac gluten sensitivity is a valid concern.
The microbiome in the gut may play a pivotal role in whether a person develops celiac disease. In an observational study using data from the Swedish Prescribed Drug Register, results indicate that those who were given antibiotics within the last year had a 40 percent greater chance of developing celiac disease and a 90 percent greater risk of developing gut inflammation (9). The researchers believe that this results from a misbalance in the microbiota, or flora, of the gastrointestinal tract from antibiotic use.
Not everyone will benefit from a gluten-free diet. In fact, most of us will not. Ultimately, people who may benefit are those who have celiac disease and those who have symptomatic gluten sensitivity. Also, patients who have positive serological tests, including tissue transglutaminase or anti-gliadin antibodies, are good candidates for gluten-free diets.
There is a downside to a gluten-free diet: potential development of macronutrient and micronutrient deficiencies. Therefore, it is wise to ask your doctor before starting gluten withdrawal. The research in patients with gluten sensitivity is relatively recent, and most gluten research relates to celiac disease. Hopefully, we will see broader studies in the future.
(1) Am J Gastroenterol. 2013;108:656-676. (2) Gut 2013;62:43–52. (3) Scand J Gastroenterol. (4) Neurogastroenterol Motil. 2013 Nov;25(11):864-871. (5) medscape.com. (6) fda.gov. (7) Am J Gastroenterol. 2011; 106(3):508-514. (8) medscape.com. (9) BMC Gastroenterol. 2013:13(109).
Dr. David Dunaief is a speaker, author and local lifestyle medicine physician focusing on the integration of medicine, nutrition, fitness and stress management. For further information, visit www.medicalcompassmd.com.