Coeliac disease and low mood: an overlooked clinical link?

Depression and persistent low mood now form a significant part of the UK’s chronic disease landscape. In England, one in five adults had a common mental health condition in 2023/24, with higher rates reported in women than men (NHS Digital, 2025). Depression remains one of the most commonly recorded conditions within primary care and mental health services.

Mood is shaped by far more than the brain alone. Inflammation, nutrient status, immune activity, gut function, blood sugar regulation, sleep, hormones and stress physiology all influence how people feel, think and function day to day.

Low mood can develop alongside chronic inflammation, nutrient deficiencies, immune activation and disruption within the gut-brain axis. Coeliac disease is one example of this connection.

How coeliac disease can present

Coeliac disease is an autoimmune condition triggered by gluten in genetically susceptible individuals. The immune response damages the lining of the small intestine and, over time, affects nutrient absorption and wider immune function.

It is commonly associated with gastrointestinal symptoms such as diarrhoea, bloating, abdominal pain and weight loss. Headaches, mouth ulcers, skin changes, anaemia, fertility issues and reduced bone density are also recognised features of the condition.

NICE advises that coeliac disease should be considered in individuals with unexplained depression or anxiety and recognises that mood-related symptoms may occur alongside the condition (NICE, 2015).

Mood symptoms can appear early and may precede diagnosis by years. Fatigue, brain fog, irritability, anxiety, depression, poor concentration and low motivation are all frequently reported. During that time, intestinal damage, malabsorption and immune activation continue in the background. A high proportion of adults with coeliac disease have received psychiatric treatment before diagnosis, in some cases for prolonged periods.

Interest has also grown around non-coeliac gluten sensitivity. Some individuals without coeliac disease report improvement in neurological, psychological or digestive symptoms following gluten removal, although the underlying mechanisms remain less clearly defined.

Nutrient absorption and mood

The small intestine is where many key nutrients are absorbed. When the intestinal lining is damaged, absorption becomes impaired. Over time, this affects energy production, neurological function and nervous system stability.

Iron, folate, B12, zinc, magnesium, vitamin D and amino acids are all commonly affected by malabsorption in coeliac disease. These nutrients are involved in processes linked to mood, cognition and brain function, including oxygen transport, mitochondrial activity, methylation, immune regulation and neurotransmitter synthesis.

Iron deficiency commonly presents with fatigue alongside low mood and reduced cognitive function. Similar patterns are seen with B12 and folate insufficiency. Low zinc can affect appetite, immune function and mood regulation. Vitamin D is also frequently low in inflammatory and autoimmune conditions and plays a wider role in neurological and immune health.

Inflammation and intestinal damage can also impair protein absorption and amino acid availability. Studies in untreated coeliac disease have shown reduced circulating tryptophan levels in some individuals (Hallert et al., 1983). Tryptophan is required for the production of 5-hydroxytryptophan and serotonin, both involved in mood regulation and neurological function.

Inflammation and the brain

Coeliac disease is an immune-driven inflammatory condition. The immune response does not remain confined to the gut and can extend into wider immune and neurological pathways, including those involved in mood and behaviour.

Inflammation changes how people feel. Fatigue, low motivation, disrupted sleep, poor concentration and social withdrawal are all commonly associated with chronic inflammatory states and are also frequently seen in depression.

The immune system and brain are closely connected through cytokines, neural signalling and endocrine pathways. When immune activation becomes persistent, changes in mood and cognitive function can follow.

During periods of heightened immune activity, tryptophan metabolism can shift down the kynurenine pathway towards inflammatory metabolites rather than neurotransmitter production. This is one proposed mechanism linking immune activation with changes in mood and behaviour.

In coeliac disease, gluten exposure drives that inflammatory response. If the condition remains undiagnosed, inflammation and immune activation may continue for years. During that time, symptoms are often attributed to stress or labelled as functional. Some individuals are treated for depression, referred for psychological support or given alternative diagnoses while the underlying inflammatory process remains unrecognised.

A systematic review found an association between coeliac disease and increased risk of depression and anxiety, although the strength of evidence varied between studies (Clappison et al., 2020).

It is also important to recognise that mood and anxiety disorders do not develop in isolation from the rest of the body. Sleep quality, circadian rhythm disruption, movement, blood sugar regulation, gut microbial activity and chronic stress exposure all influence brain function, mood regulation and inflammatory signalling.

Modern lifestyles add further complexity. Highly processed diets are associated with reduced microbial diversity, whilst antibiotics, acid-suppressing medications and chronic stress have all been linked to changes in gut integrity, immune regulation and microbiome composition.

Within that wider physiological picture, gluten-related immune activation may represent one contributing factor in susceptible individuals.

Beyond gluten removal

A strict gluten-free diet remains the foundation of coeliac disease management. Removing gluten allows the intestinal lining to heal and helps reduce ongoing immune activation.

For some individuals, mood begins to improve as absorption and nutritional status recover. Psychiatric symptoms have been shown to reduce in some adolescent populations following several months on a gluten-free diet (Pynnönen et al., 2005).

Recovery often takes time. Nutrient deficiencies may need rebuilding, and intestinal healing does not always occur immediately, particularly after prolonged periods of inflammation and malabsorption.

Ongoing symptoms can also result from continued exposure through cross-contamination or hidden dietary sources. Gluten remains widely present across processed foods, grain-based products and food preparation environments, making complete avoidance more complex than simply removing bread or pasta.

Some individuals also report sensitivity to additional dietary factors. Coffee is commonly discussed, although clinical responses vary. Certain foods may continue to aggravate symptoms or sustain gut irritation without triggering the same autoimmune response seen in coeliac disease.

Diet quality becomes increasingly important during recovery. Many gluten-free replacement products remove gluten while remaining low in protein, essential fats and micronutrient density.

Removing gluten addresses the primary trigger. Rebuilding health involves restoring nutrient status, supporting digestion, stabilising blood sugar and improving overall dietary quality.

Why this matters 

Depression and anxiety require appropriate psychological and medical support. Physiological drivers should also be considered, particularly where symptoms present alongside fatigue, brain fog, digestive disturbance, anaemia, nutrient deficiencies or an autoimmune history. This is especially relevant in women, where both autoimmune disease and mood disorders are more common.

Depression is multi-factorial. Neurotransmitters form part of the picture, alongside inflammation, stress physiology, sleep disruption, nutrient status, metabolic health, trauma and gut–brain signalling.

In some individuals, coeliac disease may sit within that wider physiological picture. A mental health condition and an underlying inflammatory or nutritional driver can also exist at the same time.

The difficulty is that attention often remains centred on mood symptoms while the underlying processes affecting physiology, immune activity and nutrient absorption continue in the background.

In summary

Coeliac disease highlights how closely gut function, immune activity and mental health are linked. It does not always present with obvious digestive symptoms and, for some individuals, fatigue, anxiety, low mood, brain fog and cognitive changes may appear years before diagnosis.

Damage to the intestinal lining affects absorption of nutrients involved in neurological function, energy production and neurotransmitter pathways, whilst ongoing immune activation and inflammation continue in the background. Altered neurotransmitter metabolism, inflammatory signalling, gut-brain communication and changes in tryptophan pathways are all thought to play a role.

Interest has also expanded beyond classical coeliac disease alone. Some individuals with negative coeliac testing still report digestive, neurological or psychological symptoms linked to gluten exposure, with proposed mechanisms involving immune activation, altered gut permeability, microbiome disruption and neuroinflammation.

At the same time, modern lifestyles have introduced wider pressures on gut and immune health, with growing research investigating their potential effects on microbial diversity, gut integrity and inflammatory signalling.

Depression and anxiety are complex and shaped by multiple interacting physiological and psychological factors. For some individuals, gluten-related disorders may form part of that wider clinical picture, which is why identifying underlying drivers can sometimes change the direction of treatment and long-term outcomes.

References

NHS Digital (2025) – Adult Psychiatric Morbidity Survey 2023/24. Reports that around 1 in 5 adults in England have a common mental health condition, with higher rates in women. www.digital.nhs.uk

NICE (2015) – Coeliac Disease: Recognition, Assessment and Management (NG20). Recommends considering coeliac disease in individuals with unexplained fatigue, anaemia, or persistent psychological symptoms such as depression or anxiety. www.nice.org.uk

Hallert, C. et al. (1983) – Reduced plasma tryptophan levels in adult coeliac disease. Demonstrates altered tryptophan metabolism in untreated coeliac patients. Published in Gut.

Pynnönen, P.A. et al. (2005) – Gluten-free diet may alleviate depressive and behavioural symptoms in adolescents with coeliac disease. Shows improvement in psychiatric symptoms following dietary intervention. Published in BMC Psychiatry.

Clappison, E. et al. (2020) – Systematic review of mental health disorders in coeliac disease. Finds an association between coeliac disease and increased prevalence of depression and anxiety, with variable strength of evidence. Published in Nutrients.

Lebwohl, B., Sanders, D.S. & Green, P.H.R. (2018) – Coeliac disease. Comprehensive clinical overview of pathophysiology, presentation and management. Published in The Lancet.

Fasano, A. & Catassi, C. (2012) – Clinical practice: Coeliac disease. Describes immune-mediated intestinal damage and systemic consequences. Published in New England Journal of Medicine.

Sapone, A. et al. (2012) – Spectrum of gluten-related disorders. Explores immune mechanisms and broader clinical presentations beyond classical gastrointestinal symptoms. Published in BMC Medicine.

O’Mahony, S.M. et al. (2015) – The gut microbiome as a key regulator of brain, behaviour and immunity. Outlines gut–brain interactions including immune and metabolic signalling pathways. Published in Neurogastroenterology & Motility.

Dantzer, R. et al. (2008) – From inflammation to sickness and depression. Describes how inflammatory cytokines influence mood and behaviour. Published in Nature Reviews Neuroscience.

Maes, M. et al. (2012) – The kynurenine pathway in depression. Explains how inflammation alters tryptophan metabolism away from serotonin production. Published in Progress in Neuro-Psychopharmacology & Biological Psychiatry.

Institute of Medicine (2001) – Dietary Reference Intakes for Vitamin B12, Folate and other nutrients. Outlines the role of micronutrients in neurological function and health.

EFSA (2015) – Scientific opinion on dietary reference values for vitamin D and micronutrients. Highlights the role of micronutrients in immune and neurological function.