ADHD, IBS and the Gut-Brain Axis: Is There a Connection?

By Natasha Hedges, Registered Dietitian & Gut-Directed Hypnotherapist

In recent years, there has been growing interest in the relationship between gut health and brain function. The gut and brain are now understood to communicate constantly through what is known as the gut-brain axis, which is a complex, two-way communication system involving hormones, immune signalling, and the nervous system.

One area that has gained increasing attention is the possible overlap between Irritable Bowel Syndrome (IBS) and Attention Deficit Hyperactivity Disorder (ADHD).

While research in this area is still developing, some individuals with ADHD also report digestive symptoms such as bloating, abdominal discomfort, and IBS-type symptoms. This article explores what is currently known, and how diet, stress, and nervous system regulation may play a supportive role.

Understanding the Gut-Brain Axis

The gut and brain are closely connected through the gut-brain axis, which links the central nervous system (brain and spinal cord) with the enteric nervous system (the nerve network within the gut).

This communication system allows the brain to influence digestion, and the gut to send signals back to the brain.

The gut also plays a role in producing and regulating neurotransmitters such as serotonin, which are involved in mood, digestion, and nervous system activity. However, these processes are complex and still being actively researched.

ADHD and Gut Health: What Does the Research Suggest?

ADHD is a neurodevelopmental condition that affects attention, impulse control, and executive functioning. It has historically been understood as primarily neurological, with strong genetic and brain-based influences.

More recently, researchers have begun exploring whether there may also be associations between ADHD and factors such as gut health, inflammation, diet, and the microbiome.

Some early studies suggest that:

• individuals with ADHD may show differences in gut microbiome composition compared with neurotypical populations

• IBS and functional digestive symptoms appear to be more commonly reported in people with ADHD

• there may be shared pathways involving stress regulation, inflammation, and nervous system sensitivity

However, it is important to emphasise that:

• the evidence is still emerging

• causation has not been established

• it is not yet clear whether gut differences contribute to ADHD, result from ADHD-related behaviours, or occur alongside it independently

At present, the gut-brain connection in ADHD is best understood as an area of ongoing research rather than a defined cause-and-effect relationship.

Why IBS and ADHD May Overlap in Practice

From a clinical perspective, there are several practical factors that may help explain why IBS symptoms and ADHD often appear together in some individuals.

These may include:

1. Stress and nervous system regulation

Both IBS and ADHD can involve differences in how the nervous system responds to stress. When the body is in a heightened stress state, digestion may become more sensitive or less efficient, which can contribute to IBS symptoms in some people.

2. Eating patterns and routine

ADHD can sometimes affect executive functioning, which may make regular eating patterns, meal planning, or mindful eating more challenging. Irregular eating habits can influence digestion and gut comfort in some individuals.

3. Heightened sensory and gut sensitivity

Some individuals with ADHD report heightened sensory awareness, including sensitivity to food textures, smells, and internal bodily sensations. In IBS, a similar mechanism is observed, known as visceral hypersensitivity, where the gut becomes more sensitive to normal digestive processes such as gas movement or intestinal activity.

While these experiences are not identical, they may overlap in how the nervous system processes and interprets internal signals from the gut. This means that normal digestive sensations may be perceived more intensely in both conditions, potentially contributing to discomfort, bloating, or abdominal awareness.

These factors do not suggest a single cause, but rather a potential overlap in how the nervous system, digestion, and sensory processing interact.

The Role of Diet in IBS and ADHD

Diet can influence both digestive comfort and overall wellbeing, although approaches should always be individualised.

In IBS, some people notice symptom changes in response to certain foods. In ADHD, some individuals also report that highly processed foods or irregular eating patterns may affect energy or focus.

Supportive approaches may include:

• regular, balanced meals where possible

• adequate fibre intake for gut health

• reducing reliance on ultra-processed foods where appropriate

• identifying individual food triggers (particularly in IBS)

Some people may benefit from a structured dietary approach such as low FODMAP under professional guidance, particularly in IBS. However, long-term restriction is not recommended, and food reintroduction is an important part of maintaining gut health and dietary balance.

Stress, ADHD, and IBS

Stress plays a significant role in both digestive and neurological functioning.

When the nervous system is under prolonged stress, it can affect:

• gut motility (how quickly food moves through the gut)

• gut sensitivity

• bowel habits

• emotional regulation

• sleep quality

Because IBS is strongly linked to gut-brain communication, many people notice symptom changes during periods of stress, anxiety, or emotional overload.

Similarly, individuals with ADHD may experience increased stress sensitivity or emotional dysregulation, which can indirectly influence digestive symptoms.

This does not mean symptoms are “psychological” or “all in your head” - rather, it reflects the close physiological connection between the brain and the gut.

Supportive Approaches

Because IBS and ADHD involve multiple interacting systems, a holistic and individualised approach is often most helpful.

1. Nutrition support

This may include:

• identifying personal food triggers (where relevant)

• supporting regular meal patterns

• avoiding unnecessary restriction

• ensuring nutritional adequacy

2. Gut-directed hypnotherapy

Gut-directed hypnotherapy is an evidence-based approach used in IBS care. It aims to support the communication between the gut and brain and may help reduce symptom sensitivity and stress-related flare-ups in some individuals.

3. Nervous system regulation

Supporting the nervous system can positively influence both digestive and emotional wellbeing.

This may include:

• breathwork and relaxation techniques

• mindfulness practices

• gentle movement or yoga-based approaches

• CBT-informed strategies for stress and coping

In Summary

The relationship between IBS, ADHD, and gut health is complex and still being researched. At present, there is no evidence that one condition directly causes the other. Instead, they may co-occur due to a combination of biological, behavioural, and nervous system factors.

These may include differences in stress regulation, gut sensitivity, eating patterns, and broader gut-brain communication. While research in this area is still evolving, understanding these overlaps can support a more individualised and holistic approach to symptoms.