Letters to a NY Times article on Non Celiac Gluten Sensitivity seem to regularly cite a study by Gibson et. all which is somewhat misleadingly entitled “No Effects of Gluten in Patients With Self-Reported Non-Celiac Gluten Sensitivity After Dietary Reduction of Fermentable, Poorly Absorbed, Short-Chain Carbohydrates.” The study was widely reported to have “disproved” gluten sensitivity, especially since the authors had previously written an article suggesting that non-celiac gluten sensitivity might be real. This small study does not disprove gluten sensitivity at all, but rather expands the things one might be sensitive to.
Gluten sensitivity can either be an early stage of celiac (the diagnostic test requires a significant amount of gut damage) or an entity of its own. In addition there can be sensitivity to other lectins in grains, wheat allergies, mechanical difficulty digesting wheat and sensitivity to fermentable, poorly absorbed short-chain carbohydrates (FODMAPs).
Many people report sensitivity to American but not European gluten-containing products, citing suspected reasons like pesticides, GMOs (escaped, not permitted), milling and short fermentation procedures and reaction to the high protein hard spring and winter wheat that makes up 70-80% of the American wheat market.
Gluten is a bit like glue in its ability to cause inflammatory actions in the human gut. Inflammation of the intestines can cause injury to the probiotic lining of the gut wall, the wall itself and finally cause gaps in the intestinal tight junctions which cause “leaky gut.” Gluten and other lectins in wheat are difficult to digest, possibly for all people, but a strong immune system generally initiates recovery. However the gliadin in wheat activates zonulin signalling which modulates the permeability of tight junctions between cells of the wall of the digestive tract. This allows larger molecules to leak into the blood stream where they elicit a cascade of antibodies and either a low immune system or repeated inflammation makes this a chronic condition.
The symptoms of gluten sensitivity as well as sensitivity to other lectins or certain FODMAPs can be frustratingly vague. Because this is a systemic reaction not all symptoms are found in the gut and may not be noticeable there at all. Besides gas, bloating , reflux and diarrhea, one might have migraines, mind fog, depression, aches and pains, autoimmune diseases and a vast array of other conditions. Since diagnostic food sensitivity testing has up to a 30% inaccuracy rate, elimination and possible rechallenge are the gold standard in identifying sensitivity. The glue-like nature of wheat and similar grains means that an elimination diet may require 1 1/2 to 2 months before the symptoms go away.
Cross-reactions may occur in the sensitive where similarly shaped molecules fit into gluten receptors on antibodies. The most important ones are dairy products including whey. You may see extensive lists based on the Cyrex Labs Array 4 which is commonly used to test further reactions to foods by the gluten sensitive but the test was not designed to test for cross-reactivity and includes a broad array of foods that do not cross-react. A well-documented discussion of this by Christina Graves is found here.
Back to the Gibson Study. 37 people, self-described as “gluten sensitive” without celiac disease were put on a low FODMAP diet then transferred to a variety of diets (high-gluten, low-gluten and low whey, low whey, or “control” high whey diets) for 1 week, followed by a washout period of at least 2 weeks. They assessed blood and fecal markers of intestinal inflammation/injury and immune activation, and fatigue. Twenty-two participants then crossed over to groups given gluten, whey, or control (no additional protein) diets for 3 days.
In all participants, gastrointestinal symptoms consistently and significantly improved during reduced FODMAP intake, but significantly worsened to a similar degree when their diets included gluten or whey protein. Gluten-specific effects were observed in only 8% of participants. There were no diet-specific changes in any biomarker. During the 3-day rechallenge, participants’ symptoms increased by similar levels among groups. Gluten-specific gastrointestinal effects were not reproduced. An order effect was observed.
The study could not rule out non celiac gluten sensitivity. Do you see the problems?
- Gluten cross reacts with whey so there was no real control
- People may be sensitive to many things, not just one
- Rechallenge took place in 2 weeks when it might take 2 months to clear out
- Elimination rather than “reduced gluten” is necessary to stop the inflammatory cascade
- All patients were worse with gluten or whey
- The notion of a “gluten specific effect” is undefined since effects are systemic but the study looked primarily at GI symptoms, fatigue and blood markers for celiac disease
- They tested IGA, IGG, and IGE but not IGM- not a complete measure of sensitivity (and there may be IGs we have not yet defined.) These tests are not highly accurate
- Absence of evidence is not itself evidence of absence. The conclusions were overstated
- The study involved only 37 subjects and only 22 finished
- Patients were self diagnosed and could have included people with carbohydrate intolerance, sensitivity to other lectins, FODMAP sensitivity, candida, or mechanical digestive problems, This is a real problem in a small study for a condition that affects millions
- There are other things than gluten in glutinous grains and if elimination works it doesn’t matter from the patient’s point of view why
What the study did show was that there are other things than gluten that could cause reactivity and elimination of other dietary constituents may help
So why is there more gluten sensitivity today? Food allergies have increased about 50% in children since 1997.
- Significant changes in the gut microbiome
- Increases in early formula feeding which can sensitize babies
- High gluten and dairy in breastfeeding moms’ diets
- Breeds of wheat which differ from historical breeds and have more gluten
- Milling changes which break down the bran and germ into smaller particles capable of entering the bloodstream
- With the new milling changes in the 1870s flour was rarely freshly ground
- We eat more processed food with injurious additives, including gluten
- We have an overall higher toxin load which stresses the immune system and raises the inflammatory load
Note that grains are the biggest source of FODMAPs in most people’s diets, and maybe secondarily dairy and beans. Stanford University’s list of low FODMAP foods are found here. Note that they suggest the quantity of FODMAPs is critical- unlike gluten sensitivity where any amount causes inflammatory cascades, so that except for diagnostic purposes this is not a list of foods to totally exclude. A GAPS diet will also exclude sensitizing foods.