New UK-led research highlights the prevalence of, and symptoms associated with, self-reported gluten or wheat sensitivity on an international scale.
One in 10 people claim to be gluten intolerant, but a much smaller number actually have a diagnosis to back themselves up.
There is a growing number of people who identify as being sensitive to gluten or wheat, as opposed to having a formal diagnosis of coeliac disease or a wheat allergy.
However, formally diagnosing individuals with non-coeliac glucose/wheat sensitivity (NCGWS) is challenging as the underlying pathophysiology remains unknown and no specific biomarkers for the condition have been identified.
As a result, there are no real estimates of how common self-reported NCGWS is on a global scale, nor has there been major efforts to explore its clinical characteristics.
Now, a new systematic review and meta-analysis, led by a team of clinical researchers from the UK, has found that one in 10 people report having NCGWS, with the rate of gluten sensitivity varying between countries and being higher in women than in men.
“This study provides the first comprehensive and methodologically robust global synthesis of the prevalence and clinical features of self-reported NCGWS,” the researchers concluded in Gut, a BMJ journal.
“NCGWS is a common condition worldwide and may represent an umbrella term for food-triggered symptomology within disorders of gut-brain interaction. The widespread use of gluten-free products, often without a clear diagnosis, highlights the clinical uncertainty surrounding this condition.”
The researchers included 25 studies in their systematic review and meta-analysis, involving almost 50,000 participants without coeliac disease or a wheat allergy from 16 countries throughout the Americas, Europe, the Western Pacific and South-East Asia. All studies were cross-sectional in nature, but only two of the included studies explored the prevalence of NCGWS in paediatric cohorts.
The overall prevalence of self-reported NCGWS was 10.3% (95% confidence interval 7.0-14.0%), with there being wide variance in the prevalence between different countries.
Self-reported NCGWS was more common in females than in males (14.0% versus 7.6%, with females being 2.3 times more likely to report NCGWS), but there was no difference in the prevalence between studies focusing on adult and paediatric populations.
“The pooled prevalence estimates ranged from 0.7% in Chile to 23% in the UK and 36% in Saudi Arabia. This variability may reflect multiple factors including study design, cultural attitudes toward gluten and health and availability and marketing of gluten-free products,” the researchers wrote.
“Historically, adherence to a gluten-free diet was limited to people with coeliac disease. However, the growing public awareness and interest in gluten-free products has led to a broader adoption of gluten avoidance among individuals without coeliac disease, either due to perceived symptom relief or misconstrued beliefs about general health benefits.”
Related
The most common symptoms of NCGWS reported by participants across the various studies were gastrointestinal and extraintestinal in nature, including bloating (95.3%), abdominal pain (89.9%), headache (89.6%), nausea (89.4%), fatigue (88.7%) and diarrhoea and constipation (87.2% and 87.0%, respectively).
Certain studies also explored the prevalence of NCGWS in specific cohorts of patients, such as those with mental health conditions and self-reported irritable bowel syndrome.
Individuals with self-reported NCGWS were 2.9 times more likely to report anxiety, 2.4 times more likely to report depression and 4.4 times more likely to report IBS compared to controls. The latter association remained when considering patients who had been diagnosed with IBS using the Rome III or Rome IV criteria (odds ratio 4.8, 95% CI 3.5-6.6).
“These associations support the notion that NCGWS lies closer to the biopsychosocial model of disorders of gut-brain interaction (DGBI) than to the immune-mediated spectrum of coeliac disease,” the researchers wrote.
“However, it is important to note that gluten may still play a role in a subset of individuals with self-reported NCGWS, particularly those with more acute and severe symptoms who are often under-represented in gluten challenge trials due to anticipated ill effects.
“Mechanistic studies exploring immune activation, intestinal barrier dysfunction and dysbiosis in this subgroup are needed to clarify potential biological pathways.
“Moreover, careful clinical assessment and baseline investigations are necessary to exclude other diagnoses with similar presentations that require specific treatment such as coeliac disease, inflammatory bowel disease, microscopic colitis, bile acid diarrhoea and other relevant gastrointestinal disorders before making a diagnosis of NCGWS.”
Forty percent of people with NCGWS reported following a gluten-free diet, while only 32% of people with self-reported NCGWS had had a doctor confirm their diagnosis – figures that concerned the researchers.
“Following a gluten-free diet without medical or dietetic oversight is associated with an increased risk of nutritional deficiencies, psychological burden and unnecessary economic cost,” they cautioned.
“A detailed assessment of both physical and psychological factors, including evaluation for overlapping DGBI, is therefore essential to avoid unnecessary dietary restrictions.
“In many cases, symptoms attributed to gluten may instead be triggered by food containing fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAPs), particularly fructans, which are commonly found in wheat-based foods like bread.”
