Non-coeliac gluten sensitivity (NCGS)

What Is Non-Coeliac Gluten Sensitivity (NCGS)?

Non-Coeliac Gluten Sensitivity (NCGS) — also referred to in the research literature as Non-Coeliac Wheat Sensitivity (NCWS) — describes a clinical syndrome in which individuals experience both gastrointestinal and extra-intestinal symptoms following the consumption of gluten-containing foods, in the absence of coeliac disease or IgE-mediated wheat allergy. Gastrointestinal symptoms typically include abdominal pain, bloating, altered bowel habit, and IBS-like discomfort. Extra-intestinal symptoms — which are frequently overlooked in clinical settings — can include fatigue, brain fog, headache, joint pain, anxiety, and low mood, reflecting the systemic nature of the condition and its relationship to the gut-brain axis. A 2025 review in The Lancet estimates that around 10% of adults worldwide self-report gluten or wheat sensitivity, though controlled challenge studies suggest the proportion with genuine gluten-specific reactivity is considerably lower — between 16 and 30% of those who self-report. Unlike coeliac disease, NCGS does not involve autoimmune destruction of the small intestinal mucosa, coeliac-specific antibodies (anti-tTG or anti-EMA), or the HLA-DQ2/DQ8 genetic haplotypes. Unlike wheat allergy, it does not involve IgE-mediated immune responses or anaphylaxis. It is, clinically, a diagnosis of exclusion — reached only after both coeliac disease and wheat allergy have been formally ruled out by a healthcare professional, and after symptoms resolve on a wheat-free diet and recur on reintroduction. The NHS coeliac disease pathway must always be the first step before any conclusion about NCGS can be drawn.

The Fructan Question: Is Gluten Really the Culprit?

One of the most significant developments in NCGS research over the past decade has been a fundamental challenge to the assumption that gluten itself is the primary trigger. Wheat contains not only gluten proteins but also FODMAPs — specifically fructans, chains of fructose molecules that are poorly absorbed in the small intestine and rapidly fermented in the colon. A landmark 2018 double-blind, placebo-controlled crossover trial by Skodje et al., published in Gastroenterology, found that in 59 individuals with self-reported gluten sensitivity, fructan challenge produced significantly higher symptom scores than either gluten or placebo. Research from Monash University reached a similar conclusion: FODMAPs, not gluten, were the primary symptom trigger in the majority of individuals with NCGS. This distinction has profound practical implications. It means that a significant proportion of people who believe they cannot tolerate wheat may, in fact, be reacting to its FODMAP content rather than its gluten proteins. Gluten-free products are often lower in FODMAPs simply because they are made without wheat — which may explain symptom improvement on a gluten-free diet in the absence of any true gluten sensitivity. It also opens up a clinically important alternative: rather than eliminating wheat entirely, reducing its FODMAP content through food processing — specifically, through long sourdough fermentation — may restore tolerability for many people.

How NCGS Differs from IBS and Wheat Allergy

The clinical picture of NCGS overlaps considerably with Irritable Bowel Syndrome (IBS), which has led to significant diagnostic confusion. Both conditions can present with abdominal pain, bloating, and altered bowel habit, and both may respond to a low-FODMAP diet — further complicating the picture. The key distinction is mechanistic: IBS is classified as a disorder of gut-brain interaction, while NCGS is thought to involve activation of the innate immune system, altered intestinal barrier function, and gut dysbiosis. A review in Clinical Gastroenterology and Hepatology notes that the two conditions frequently co-exist, and that unnecessary long-term gluten avoidance can itself reduce dietary fibre diversity and negatively affect the gut microbiome. Wheat allergy is a separate entity: an IgE-mediated allergic response that typically produces immediate reactions — within minutes to two hours of ingestion — including urticaria, respiratory symptoms, or anaphylaxis. It is diagnosed through skin prick testing or specific IgE blood tests and managed through the NHS allergy pathway. NCGS, by contrast, tends to produce symptoms hours to days after exposure, with no identifiable immunological marker.

Diagnosis and the State of the Research

NCGS was formally classified as a distinct clinical entity by Dr Alessio Fasano and colleagues in 2011, using a framework dividing gluten-related disorders into autoimmune (coeliac disease), allergic (wheat allergy), and immune-mediated (NCGS). Despite this, diagnosis remains challenging. There is currently no validated biomarker for NCGS — no blood test, no biopsy finding, no genetic marker that confirms it. Proposed candidates including IgG anti-gliadin antibodies, faecal calprotectin, and zonulin have all shown conflicting results. The gold standard remains the Salerno Experts’ Criteria: a double-blind, placebo-controlled gluten challenge following a period of strict exclusion — a protocol that is largely impractical in routine clinical care. The research is further complicated by the significant role of nocebo effects — the expectation of symptoms generating symptoms — demonstrated in controlled challenge studies. This does not mean NCGS is psychosomatic; it means that clinical trial design must be exceptionally rigorous to isolate the genuine physiological trigger. A 2025 narrative review in Nutrients concludes that NCGS is a real and distinct condition, but that symptoms are likely driven by a combination of fructans, gluten proteins, amylase-trypsin inhibitors (ATIs), gut-brain axis dysregulation, and individual variation in gut microbiome composition.

Sourdough Fermentation, FODMAPs, and NCGS: The Clinical Case

This is where sourdough fermentation becomes clinically relevant. Long, slow sourdough fermentation — driven by a mature, active sourdough starter over a minimum of eight to twelve hours — substantially reduces the fructan content of wheat bread. Studies have demonstrated fructan reductions of 69–75% in well-fermented sourdough compared to the same flour made into bread with commercial yeast. A conventional fast-fermented loaf retains the majority of its fructan load. A properly fermented sourdough does not. Sourdough fermentation also reduces amylase-trypsin inhibitors (ATIs) — wheat proteins increasingly implicated as drivers of innate immune activation in NCGS — through the proteolytic activity of lactic acid bacteria. The partial hydrolysis of gluten proteins during long fermentation further reduces the immunoreactivity of gliadin peptides, which may improve tolerability for individuals with non-coeliac wheat sensitivity. The acidification of the dough — through lactic and acetic acid production — supports this enzymatic activity and simultaneously reduces phytic acid, improving mineral bioavailability. It is worth being precise here: sourdough fermentation cannot and does not make bread safe for people with coeliac disease. Coeliac disease requires lifelong strict gluten avoidance, and no level of fermentation changes that clinical reality. The evidence for improved tolerability in NCGS, while promising, is not yet sufficiently consistent across studies to constitute a universal clinical recommendation. What the research does support is that for many individuals with wheat sensitivity who do not have coeliac disease, the fermentation process is a meaningful variable. The bread that caused symptoms was almost certainly a fast-fermented, commercially produced loaf — a fundamentally different food, made by a different process, with a very different nutritional profile from a properly made long-fermented sourdough. The BALM Protocol — Baking as Lifestyle Medicine, developed through doctoral research at Middlesex University — takes this further. Rather than treating fermentation as a single variable, BALM addresses bread-making as a systems intervention: combining long fermentation with grain diversity, including einkorn, emmer, and other wholegrain heritage flours with distinct gluten and FODMAP profiles, alongside prebiotic fibre diversity and targeted botanical additions. Clinical research applying the BALM Protocol demonstrated 100% improvement in gut microbiome diversity and 89% improvement in mental health outcomes in participants — outcomes that reflect the systemic reach of bread made to genuinely therapeutic standards. For individuals with suspected NCGS, personalised bread-making informed by nutrigenetic testing — including assessment of markers relevant to wheat and gluten metabolism — offers a more precise and individually tailored approach than blanket wheat avoidance. You can find out more about personalised consultations and testing at The Sourdough School.

My hypothesis on why people with NCGS report they can eat bread more easily.

The fermentation of bread has been at the centre of my clinical and research practice for decades, and the question of why so many people struggle to digest modern wheat bread — while often tolerating a long-fermented sourdough — sits at the heart of that work. I do not believe the answer lies simply in the gluten itself, nor entirely in the FODMAP content of the grain. My hypothesis, informed by the science and by years of working with people who have struggled with wheat, is that what matters most is what happens to the bread during fermentation. When a dough undergoes long, slow sourdough fermentation, the lactic acid bacteria present in the sourdough starter progressively acidify the dough. This falling pH activates the grain’s own endogenous proteases — enzymes that begin breaking down the gluten protein structure — and creates the conditions under which the LAB’s own peptidases can work most effectively. Pioneering research by Gobbetti and colleagues demonstrated that selected sourdough LAB are capable of hydrolysing gliadin fractions — including peptide sequences specifically implicated in immune reactivity — through the action of cell wall-associated proteinases and intracellular peptidases. Further work on gluten proteolysis mechanisms has confirmed that it is the proline-rich nature of gliadin that makes it so resistant to normal digestive enzymes; proline residues at peptide bonds actively block cleavage, and the LAB peptidases in a well-maintained sourdough starter are among the few biological agents capable of targeting exactly these bonds. My hypothesis is that this sustained proteolytic activity may represent a meaningful part of why long-fermented sourdough is better tolerated by many people with non-coeliac gluten sensitivity. If the peptide sequences that the immune system is primed to recognise are progressively dismantled during fermentation, the immune burden of eating that bread is potentially reduced — not eliminated, but reduced. This is distinct from FODMAP reduction, which operates at the carbohydrate level, as explored in Skodje et al.’s landmark fructan study. It may be that both mechanisms are operating simultaneously, and that it is their combination — alongside the prebiotic fibre benefits central to the BALM Protocol — that produces the tolerability improvements I have observed clinically over many years. This remains a hypothesis. It is not a clinical recommendation, and it is emphatically not a suggestion that people with coeliac disease eat sourdough bread. But it is, I believe, a hypothesis worth taking seriously. If you would like to explore your own wheat sensitivity in the context of your individual genetics and gut microbiome, you can find out more about consultations and testing at The Sourdough School. All information on this page is provided for educational purposes. It is not intended as a substitute for professional medical advice. If you suspect you have coeliac disease, non-coeliac gluten sensitivity, or any wheat-related disorder, please seek a formal assessment from a qualified healthcare professional before making dietary changes. “` — Ready to paste. The image and column structure are untouched. Does that feel right?

All reasonable care is taken when writing about health aspects of bread, but the information it contains is not intended to take the place of treatment by a qualified medical practitioner. You must seek professional advice if you are in any doubt about any medical condition. Any application of the ideas and information contained on this website is at the reader's sole discretion and risk.