Beyond Celiac: Understanding Non-Celiac Gluten Sensitivities (NCGS)

May 14, 2024

Celiac disease is an autoimmune enteropathy condition triggered by gluten (a protein found in wheat). Exposure causes symptoms such as severe gastrointestinal (GI) problems including diarrhea or constipation, bloating, and pain, as well as joint pain, chronic fatigue, headaches, brain fog, and skin problems. Celiac disease has one clear treatment: avoid gluten completely.1-5 A person can also have an allergy to wheat, causing similar symptoms; a lesser understood condition referred to as non-celiac gluten sensitivity (NCGS) can also occur.1-6 Researchers have defined NCGS as a syndrome that is characterized by both GI and extraintestinal (joint, skin, systemic) symptoms with gluten-exposure.5,6 

Though established biomarkers for NCGS diagnosis do not exist at this time, there is evidence that this condition causes systemic inflammation and damage to the intestinal epithelium.3 Some researchers believe that components of wheat other than gluten may be at the root of NCGS and advise that the term non-celiac wheat sensitivity (NCWS) is used as some people are also triggered by grains such as rye, barley, and oats.5-7

While challenges with identifying and diagnosing NCGS exist, current estimates indicate that prevalence is likely 1-2% of the North American population, mimicking rates of celiac disease.Some survey studies have indicated higher rates around the world, up to 14.9% for example, in Australia.5

NCGS Diagnosis Challenges

Because symptoms overlap, it’s important to rule out both celiac disease and wheat allergy before exploring NCGS.1,5 Newer studies show that there is a distinct immune response for people who are gluten sensitive but non-celiac.2 In a study of 160 people (80 with NCGS, 40 with celiac disease, and 40 healthy control subjects), immunoglobulin IgG1 and IgG3 antibodies were increased in the celiac group compared to the other two groups. The NCGS group produced higher levels of IgG2 and IgG4 if exposed to gluten.2,3  Though the antibodies responding may differ, there’s a gut inflammation response present, which is why symptoms are so similar.1-3

Subjective testing and self-diagnosis are common and can be problematic. Professional evaluation and guidance are needed, and the importance of the role of the expert healthcare practitioner cannot be overstated enough.6 The first step in diagnosing NCGS is generally ruling out celiac disease and wheat allergy.2,6 While there are no validated blood tests for NCGS, some researchers suggest drawing anti-gliadin IgG4 antibodies and fatty acid-binding protein 2 (FABP2 – a marker of intestinal epithelial cell damage) to determine that a sensitivity is present.2,3 

Symptoms often appear when gluten is ingested (often within hours of consumption) and are relieved with gluten avoidance. Once gluten has stopped being consumed, symptoms can subside within hours to days. Common symptoms include abdominal pain and bloating in both upper and lower regions, diarrhea and/or constipation, reflux, and nausea.5,7  Brain fog, fatigue, headache, anxiety, joint and muscle pain, and skin rashes are also commonly reported with gluten ingestion for people with NCGS.5,7
Importantly, symptoms of NCGS can overlap with irritable bowel syndrome (IBS) though studies have shown that in comparison, people with NCGS have higher rates of anemia, weight loss, allergy symptoms or eczema, anti-gliadin IgG antibodies present, and extraintestinal symptoms (systemic problems like skin, brain fog, or joint pain).6-8,10  One study showed that 20-37% of people with NCGS also met the criteria for IBS.5,9 If you suspect that a patient has NCGS, it’s critically important to refer to a specialist to get the right diagnosis and a clear treatment plan as this condition can mimic the symptoms of several GI problems.6

Gluten Reduction: Yes or No?

Because gluten or other aspects of wheat or other grains can cause severe symptoms in people with NCGS, elimination is the only known treatment currently.5,6 Unlike celiac disease, which requires strict gluten elimination, many researchers suggest a gluten/wheat challenge through exposure after a period of elimination to assess clinical response and if symptoms present as they did prior to elimination in people with NCGS.6,8 Some studies show that even when patients are advised to reintroduce gluten, they decline to do so because of the fear of symptoms returning. Though studies on the subject are limited at this time, some indicate that people with NCGS do in fact stay on gluten-free diets long-term.5

Researchers have identified that certain short-chain carbohydrates, namely fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAPs) can also trigger symptoms in people with NCGS.5.11 This finding mirrors evidence that NCGS and IBS symptoms and triggers can overlap. Wheat (as well as rye and barley) contains fructans and galacto-oligosaccharides that can cause symptoms in NCGS patients.5 Though a low FODMAP diet can reduce symptoms in some patients, health care practitioners should carefully weigh the pros and cons of this type of diet long-term as it’s very restrictive and has been associated with reduced micronutrients and dietary antioxidants.5

Nutritional Considerations

Nutrition deficits can occur when following a gluten-free diet. Studies have shown that gluten-free diets can be higher in calories, saturated fat, and sugar, and lower in fiber, folate, vitamins D and E, iron, calcium, magnesium, and zinc than non-gluten-free diets.12-15  

Healthcare practitioner support from experts such as registered dietitian nutritionists are key for helping anyone avoiding gluten to also meet their nutrient needs correctly.14,15 Studies have shown that registered dietitian support and education improves adherence to gluten-free diets effectively. A small study of 72 patients with celiac disease received education about gluten sources to avoid; 48 people participated in a one-year follow-up and those who received the education about gluten sources had improved adherence to the diet over time. However, education did not seem to improve other aspects of diet quality and people with celiac disease on a gluten-free diet did not meet requirements for calcium, iron, vitamin D, folic acid, or fiber.15 This study indicated that the role of the dietitian for people on gluten-free diets needs to be expanded to help improve diet quality over time.15

Nutritional supplements can be helpful for people avoiding gluten to better meet their needs. Noteworthy, nearly all Orgain® products are gluten-free, making them a good choice for helping patients meet their protein and micronutrient needs. 

Key Takeaways for Practitioners 

Some of the most critical first steps a healthcare professional can take is to listen to their patients if they are struggling with symptoms and suspect NCGS. Ask open-ended questions about their history and experience and stay up to date on lesser understood conditions like NCGS. Be sure to refer patients out for celiac and wheat allergy testing, depending on your scope of practice, and consider guiding patients towards doctors who specialize in celiac disease and food allergies who can rule these problems out.

If it’s determined that a patient may have NCGS, healthcare practitioners can provide personalized dietary counseling on how to ensure nutritional adequacy on a completely gluten-free diet. Educating about hidden sources of gluten like soy sauce, deli meats, and condiments or foods at risk for cross-contamination like oats is a key step in helping patients stay 100% gluten-free.4 A multidisciplinary team can help patients monitor their health status long term, can decide how much, if any, gluten is safe for people with NCGS and weigh the pros and cons of other possible interventions such as a low FODMAP diet. 


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