Why switching to a gluten-free diet could help treat these common mental health conditions, say these leading psychiatrists

Asked to list the symptoms of coeliac disease or gluten sensitivity, and no doubt you think of tummy troubles: cramps, bloating, nausea and uncomfortable digestive issues.

But what if we told you coeliac disease and non-coeliac gluten sensitivity can also affect your mind, not just your body – and could contribute to everything from anxiety to ADHD, depression to schizophrenia?

Again and again, our clinical and research work in the field of psychiatry has shown us that eating gluten can have profound consequences for some people’s mental health: Jessica is an award-winning psychiatrist with 40 years’ experience, specialising in autism; Deanna, a professor of psychiatry and internationally recognised mental health researcher; and Sharon, a clinical and research psychiatric physician assistant who focuses on schizophrenia.

Our research has shown that there is a relationship between gluten – which is found in wheat, barley and rye – and certain mental and neurological illnesses that affect millions of people.

In 2019, we conducted a groundbreaking study in which people with schizophrenia and gluten sensitivity experienced significant improvement in their psychiatric symptoms after just five weeks of following a gluten-free diet.

Their stories are not unique. Other patients have had their mental health and neurological symptoms – from seizures to depression – either entirely or partially alleviated simply by giving up gluten.

Evidence shows that gluten’s effect on psychiatric symptoms may impact up to one in 17 people – yet few medical clinicians are aware of this, despite studies documenting this link for more than ten years.

It doesn’t help that research that links gluten and certain mental health conditions is mostly published in gastroenterology and immunology journals, which psychiatry and neurology clinicians are less likely to see.

To people who think that a gluten-free diet as a mental health treatment sounds like a fad or a farce, we would say that we too thought the same thing at first – we simply never imagined that food and diet could also be good medicine.

Not least because in the traditional view of the medical establishment, which separates dietary from pharmaceutical interventions, dietary treatment is still often considered as somehow ‘complementary’ or ‘alternative medicine’, and there is limited nutritional instruction in medical schools.

Jessica was certainly initially uninformed, even as a practising doctor. But then in 2010, when her son was checked for coeliac disease, she also underwent testing.

As someone who had suffered lifelong from a ‘nervous stomach’ and constipation – as well as panic attacks from the age of five, migraines and a profound fear of getting lost since adolescence, not to mention extreme fatigue and brain fog – she was astonished to find that after just 48 hours on a gluten-free diet, she felt her fears evaporated and her mind was clear; she had no digestive discomfort and boundless energy.

An astonishing turnaround for someone who previously, when walking her dog, would feel so exhausted she felt she could lie down and sleep on the pavement.

But it’s not just individuals’ stories: there is way too much science now to support a gluten-free diet as a mental health treatment to ignore it.

So how could something you eat – gluten – affect mental wellbeing? This comes down to those two conditions, coeliac disease and non-coeliac gluten sensitivity.

Coeliac disease (CD) is a condition where your immune system attacks your body after eating gluten. It can cause damage to your gut, shrinking and flattening the finger-like villi of the small intestine, making it difficult for the body to absorb nutrients.

CD affects around one in 100 people – although it’s estimated that only a third of coeliacs are diagnosed, which means there could be up to half a million people in the UK unknowingly living with the condition.

CD is diagnosed via a blood test for antibodies, or an intestinal biopsy to check for inflammation.

Less is known about non-coeliac gluten sensitivity (NCGS), but it’s thought to affect ten times as many people as CD and has many of the same physical effects.

However, tests like those above will often come back negative, meaning NCGS is often diagnosed purely based on symptoms.

The main test for NCGS is a gluten challenge test – put very simply, this involves being gluten-free for six weeks, then reintroducing gluten. But this is difficult to do even in a healthcare setting.

Blood tests can look for levels of antibodies (specifically, called AGA IgA and AGA IgG) – these are raised in many autoimmune and inflammatory conditions.

However, we must emphasise that raised levels are not specific for NCGS. But if they are positive, together with negative coeliac disease tests, it suggests that NCGS should be considered as a possibility. But it should also be noted that some people have CD or NCGS without any signs of gastrointestinal symptoms.

Apart from digestive problems, other signs gluten may be an issue include rashes, having other autoimmune illnesses (such as type 1 diabetes or thyroid diseases), or having a close family member with gluten sensitivity.

So even when there’s no evidence of tummy issues alongside a mental health condition, we believe testing for CD, or considering NCGS as a possibility, would be prudent. That’s because a gluten-free diet can be transformational for some patients.

And, while we would never advise stopping medication without consulting a doctor, we believe more clinicians should consider advising some patients with mental health conditions and ‘at-risk’ factors (for example, autoimmune disorders or gut symptoms) to get tested and consider ditching gluten.

So how does CD and NCGS affect the brain? There are a number of potential routes.

For example, when someone with gluten sensitivity consumes gluten, their body may produce antibodies to fight it (called IgG).

This can cause inflammation and contribute to gut damage, which can lead to a ‘leaky gut’ – a weakened gut wall – which allows these antibodies to leak into the bloodstream: as a result, inflammation may occur in other parts of the body, including the brain. And there, these gluten-related antibodies may attack brain cells or receptors.

It’s worth noting that a study by Deanna and her colleagues – published in the journal Schizophrenia Research in 2019 – found about a third of their patients with schizophrenia had high levels of inflammatory markers in their blood, along with elevated IgG antibodies, and increased gut permeability.

Anxiety is probably the most common of all modern mental health conditions – and has been linked to gluten sensitivity for some time.

There are several theories for this. We know, for example, that 95 per cent of the body’s serotonin – the so-called ‘happy hormone’ and a key brain chemical messenger believed to be involved in anxiety disorders – is produced by the gut (where it plays a number of roles including helping with how food moves through the gut).

Small amounts of serotonin are squeezed into the bloodstream through gut contractions, known as peristalsis, which propel food through the digestive tract.

Serotonin production is also influenced by the balance of microbes within the gut.

So clearly if your gut is affected by gluten, this can affect your serotonin.

While large studies are not yet available, several smaller trials – for example, one published in 2002 in the Journal of Psychosomatic Research, and another in the Scandinavian Journal of Gastroenterology in 2008 – have shown ‘reactive’ anxiety (like that shown in response to stressful situations, social phobias and panic disorders) is more prevalent in people with CD.

Some studies found up to 85 per cent of patients with CD experience anxiety, while one 2014 trial found about 40 per cent of people with gluten sensitivity were anxious. In this latter research, which included almost 500 people, anxiety could occur within hours to days of consuming gluten.

Of course, it is also possible that anxiety is linked directly to the discomfort of gut symptoms brought on by consuming gluten. But another large study of more than 3,000 people who had positive blood markers for CD without gut symptoms found they experienced significant improvements in anxiety after following a gluten-free diet for a year, reported the journal Gastroenterology in 2014.

What this means for individual patients is highlighted in published case reports.

Take the seven-year-old whose story was reported in the journal Global Advances in Health and Medicine in 2012. From the age of three, he was intensely fearful of germs – even the lead in a pencil terrified him – and was diagnosed with OCD and anxiety.

A child psychologist began cognitive behavioural therapy, which helped a little.

A persistent, itchy rash was then proved to be caused by a skin allergy to wheat, barley and rye.

While blood tests for CD weren’t completed, he began a gluten-free diet. After ten weeks, his mother rated his OCD and anxiety as 99 per cent better, and his skin rash vanished. The rate of his improvement after a gluten-free diet makes it highly likely he had CD or non-coeliac gluten sensitivity.

While depression has no single cause, it has been linked to gluten. One large study, published in the Journal of Psychosomatic Research in 2013, which looked at more than 2,000 people with CD, found that more than one in three experienced depression in their lifetime.

As well as serotonin, it’s thought there may be a direct physiological link between CD and depression, thanks to the gut’s immune response resulting in inflammation that affects the brain. It’s also significant that people with intestinal inflammation (or damaged villi, as with CD) do not absorb vitamins and nutrients normally.

Deficiencies in B vitamins, for example, may contribute to depressive symptoms. And gut inflammation caused by gluten leads to a reduction in absorption of tryptophan, an amino acid required for the production of serotonin, that all-important happy hormone.

In another case, published in the American Journal of Gastroenterology in 1999, a 22-year-old woman who had suffered with severe depression since adolescence, yet for whom antidepressants had little impact, swapped to a gluten-free diet.

After three months, she experienced such rapid improvement that she was able to discontinue all psychiatric medication.

Two years later, her doctors reported she remained psychiatrically stable. (She’d gone gluten free after her three-year-old child was diagnosed with CD, and blood tests and an intestinal biopsy showed she shared the condition, despite only ever having some tummy trouble between the ages of one and two herself.)

Patients with ADHD, one of the most common neuropsychiatric diagnoses associated with coeliac disease, may also benefit.

In a study published in 2022, after 12 months of a gluten-free diet, people with CD and ADHD experienced such an improvement in their ADHD symptoms that they matched the healthy ‘control group’ symptom scores.

Again, this is thought to be linked to gluten causing inflammation in the brain.

Perhaps the most exciting research we have been personally involved in examined links between schizophrenia and gluten consumption – especially considering there is no pharmaceutical cure for schizophrenia.

The initial clue for this association was first noted years ago, when researchers established that schizophrenia was rare in certain countries, or during certain periods of history when wheat was not part of the common diet.

Genetic studies later emerged which showed certain genes carry the risk for both schizophrenia and CD, such as the MY09B gene.

In 2009, Deanna took part in a major study of more than 1,400 people with schizophrenia. It found almost 25 per cent showed elevated levels of an antibody to gluten, while only 3 per cent of the control group – i.e. people without schizophrenia – had elevated gluten antibodies.

Eventually, in 2019, we expanded our research to the gold-standard double-blind test – where neither testers nor subjects know who is being treated with the placebo, and who is not – to see whether removing gluten could help people with schizophrenia who also had gluten-sensitive antibodies.

Participants remained on their psychiatric medication while consuming identical-looking protein shakes – one containing wheat, one without. After five weeks, there was significant improvement in the gluten-free group.

We also found measures of inflammation in the blood improved on a gluten-free diet – as well as another chemical marker in the blood associated with schizophrenia called kynurenic acid (the study was published in 2019 in the Journal of Psychiatry and Neuroscience).

It’s clear this is an area that deserves more investigation. Because, vitally, compared with other available treatments for mental health issues, gluten-free diets may help reduce or eliminate the root cause of the illness, not just reduce symptoms.

Families contact us weekly, often seeking new options for a loved one because their own doctors ran out of ideas long ago and medications have not worked.

Trying to find answers in a healthcare system where everything is so compartmentalised is not easy.

After all, traditionally, gastroenterologists and psychiatrists would not communicate about a patient. We believe it’s high time that changed.

• Adapted from Get Your Brain Off Grain by Jessica Hellings, Deanna Kelly and Sharon Pugh (Hammersmith Health Books, £19.99), published on June 19. © Jessica Hellings, Deanna Kelly and Sharon Pugh 2025. To order a copy for £17.99 (offer valid until June 24, 2025; UK P&P free on offers over £25) go to mailshop.co.uk/books or call 020 3176 2937.