Gut health has become a popular topic in recent years, and research has proven that it could be responsible for more than first thought. From the nervous system to the immune system to the endocrine system, our gut health has been connected to a number of functions within the body, so it is no surprise that those with ADHD may wonder if there could also be a link between poor gut health and ADHD symptoms.

Here, we are exploring this potential link, what the gut-brain connection actually is, how it influences brain function, the research on its connection to ADHD, practical tips for improving your gut health, and when and how to seek professional support for ADHD. 

At Augmentive, we aim to provide holistic, tailored mental health support to everyone so they can live their life to the fullest, so if you have questions about ADHD and gut health, we can help. 

What is ADHD?

ADHD is an acronym for attention deficit hyperactivity disorder, which is a type of neurodivergence causing a person’s brain to be hard-wired differently to that of a neurotypical person. The three types of ADHD are characterised by the symptoms they produce, and these include hyperactive-impulsive ADHD, inattentive ADHD, and combined ADHD. Some of the symptoms of ADHD include: 

Inattention symptoms

• Struggling to maintain attention during long tasks, and missing details
• Regularly making what seem to be careless mistakes
• Struggling to organise tasks and activities, and to manage time
• Often losing items like keys or phones
• Forgetting important things, such as paying household bills or attending appointments

Hyperactive symptoms

• Fidgeting or squirming a lot
• Prolonged restlessness and difficulty sitting still for long periods of time
• Being unable to engage in fun activities in a quiet manner 
• Excessive talking, interrupting, or answering questions before they are finished
• Difficulty waiting, such as in a line or for their turn to speak 
• Becoming easily distracted by unrelated things and external stimuli 

These symptoms can lead to issues in various areas of life, and can impact things like career, relationships, parenting, finances, achieving personal goals, and more. It is important to remember ADHD usually affects women differently to men, with inattentive ADHD being more common in women, and hyperactive ADHD being more common in men. 

Is there really a connection between the brain and the gut? 

The gut-brain connection is sometimes known as the gut-brain axis, and use of these terms usually refers to the complex link between the gastrointestinal system and the brain. This is a bidirectional relationship, meaning the health of our gut can significantly affect our brain function, and vice versa. 

Sometimes, the gut is called the "second brain" due to its surprising network of neurotransmitters, which until recently were thought to be found only in the brain. In fact, according to recent studies, neurotransmitters such as serotonin, dopamine and norepinephrine–which play a crucial role in regulating mood and emotions–are produced by gut microbiota and can affect gut permeability, giving them the ability to influence the gut-brain axis. Other studies suggest an estimated 90% of our serotonin is actually produced by the gut. 

At the centre of the gut-brain connection is the microbiome, which is a diverse community of microorganisms that live in our digestive tract and have links to many of our bodily functions, from our digestion to the production of chemicals affecting our brain function and overall health. An unbalanced gut microbiome has been connected to a number of health issues, such as inflammatory bowel disease (IBD), irritable bowel syndrome (IBS), coeliac disease, obesity, metabolic syndrome, cardiovascular diseases, allergies and more. Links have also been made to mental health conditions like depression and anxiety, as well as several neurological and neurodevelopmental disorders like multiple sclerosis, Alzheimer’s, Parkinson, autism, and the subject of our focus here, ADHD. 

When we understand how our brain and digestive system have evolved simultaneously to work together, we can acknowledge the potential connection between an unhealthy gut microbiome and conditions like ADHD. What we consume each day is so influential to our physical health, but ensuring we get the correct nutrients to protect our mental health can make a big difference to our overall wellbeing. For those living with ADHD, a gut-friendly diet could have a positive impact on the severity of symptoms.

Can ADHD symptoms be affected by gut health? 

We know from recent studies that ADHD symptoms can be impacted both negatively and positively by gut health. A 2020 study suggested conditions such as depression, anxiety, bipolar disorder, autism and ADHD were all related to behavioural, cognitive and emotional disturbances that originate from disordered brain function linked to neuromodulators like serotonin and dopamine. As a result, evidence shows that development and regulation of the gut microbiome could play a significant role in mental health, and this has been confirmed in animal and human studies alike. 

One 2020 study put microorganisms from the intestinal tracts of people (both with and without ADHD) into mice, and found the mice who received microbiota from those with ADHD saw changes to certain areas of the brain associated with neurodevelopmental disorders, which suggests a strong correlation between ADHD symptoms and gut health. 

Another study looked at the fungi found in the human microbiome, and discovered that imbalances of certain fungi were more common in those with ADHD, specifically a fungus called candida thought to be responsible for increasing the permeability of the gut lining, which can lead to inflammation. 

As well as adults with ADHD, a 2021 study on children with ADHD found that a poor gut microbiome could be connected to diverse neurological and neurodevelopmental disorders in children and adolescents, and could lead to not only core ADHD symptoms, but also comorbidities like sleep disorders. A further 2023 study found children with ADHD who were on psychostimulant medication had a lower abundance of certain bacteria strains, and higher plasma levels of certain vascular inflammatory markers, meaning there is also scope to research the effects of ADHD medications on gut health and vice versa. 

Treatments focused on the microbiome have already shown positive results, with some clinical studies finding that probiotics could be used to treat depression, anxiety and stress. Due to this success, researchers are also beginning to explore the possibility of microbiome-related treatments with the goal of helping to manage ADHD symptoms, although these are not yet considered mainstream ADHD treatments. 

Past studies indicate those with ADHD frequently experience gastrointestinal dysfunction, which means there is certainly a promising outlook for further research into the ADHD gut-brain axis. Current research is focused on altering, eliminating or preventing the development of certain microbes in the gut for those with ADHD to help minimise the severity of impulsivity, inattention and hyperactivity symptoms.

Can poor gut health cause ADHD? 

Despite the strong relationship between gut health and ADHD symptoms, and the microbiome’s ability to influence these symptoms, it is not currently believed that poor gut health could be the initial cause of ADHD developing in the first place. Further research must be done to determine the validity of this, but at present, existing study findings suggest gut health can only exacerbate ADHD symptoms, not cause them. 

What are some practical ways to improve gut health? 

There are many differing opinions on the best ways to improve and maintain gut health, and considering what the ‘perfect diet’ is for ADHD symptoms is another layer that requires nuanced research and likely personalised protocols in order to positively impact each person’s gut microbiome for the desired effects. 

More research is needed to fully understand how certain gut health interventions–such as dietary changes or probiotics–could best support ADHD treatment. However, if successful these interventions could open doors for alternative treatment options for those who are intolerant to ADHD medications. 

There are many ways to improve gut health, but some that may help include: 

Make appropriate dietary changes 

The gut microbiome is made up of trillions of bacteria and other microorganisms, and when these are not kept balanced and healthy through diversity of food intake and other factors, this can potentially affect the production of neurotransmitters such as serotonin and dopamine, which are key in mood regulation and cognitive function, and are important to the regulation of ADHD symptoms. 

Our gut microbiome is primarily influenced by the foods we eat, so overhauling your diet to incorporate healthier foods and eliminate problem foods is likely the best (and most accessible) way for anyone to start taking control of their gut health. This might include:

• Eating more fibre-rich foods such as fruits, vegetables, whole grains and legumes. 
• Eating more plant-based foods, since some evidence suggests a vegetarian diet could be linked to lower risk of ADHD symptoms.
• Hydrating by drinking plenty of water, and adding more hydrating foods to your diet such as soups and smoothies. This could help with your digestive health and maintain the mucosal lining of the intestines. 
• Avoiding processed foods. Try to reduce your intake of highly processed foods and sugars, which can disrupt the balance of gut bacteria and contribute to inflammation.
• Eating more fermented foods like miso, tempeh and kombucha, which are all natural sources of probiotics. 

Manage your stress levels 

Studies suggest the composition of the gut microbiome depends primarily on dietary habits and stress, so this is another key factor to consider if you want to improve your gut health. To do this, you could experiment with what works best for you, by trying techniques such as mindfulness, meditation, yoga, deep breathing exercises, or spending time outdoors, which has many health benefits. 

Get regular exercise 

There are so many benefits to exercise, and the gut microbiome can also benefit from regular physical activity. This could be anything from walking, swimming or yoga to something more strenuous like running or weight lifting. Exercise can enhance gut motility and improve overall health, as well as having positive impacts on general ADHD symptoms.

Consume probiotics and prebiotics

There is growing research on probiotics and prebiotics, which are thought to offer balance to the gut microbiome. Foods such as live yoghurt, kefir, sauerkraut and kimchi are known to introduce what could be considered ‘good’ bacteria to the gut in order to support the growth of healthy bacteria over unhealthy bacteria. 

A 2021 study found the results of probiotic supplementation for ADHD symptoms were varied and inconclusive, however other studies have identified evidence to suggest kefir could have a positive impact on microbiome composition. Although more research is required to gain a proper understanding of the potential benefits of this kind of supplementation, probiotics and prebiotics have been found to have benefits for our general health, so there is no harm in adding more pro- and prebiotic foods to your diet to see if this works for you. 

It is also worth knowing that antibiotic use can alter the diversity of the gut microbiome, so being mindful of this and only taking antibiotics when absolutely necessary can help to preserve healthy gut bacteria. 

Get plenty of sleep 

Sleep is important for our health in general, but can also support our gut health. Try to aim for 7-9 hours of sleep each night in order to promote healthy gut function, but prioritise deep sleep over the amount of time you are actually in bed. Studies suggest getting enough sleep could help to keep ADHD symptoms at bay, and it is known that lack of sleep can exacerbate these symptoms. 

Keep your bedroom cool, invest in blackout blinds for less light, avoid screens and other sources of blue light for at least an hour before bed, and try to go to sleep and wake at the same times every morning and night to encourage consistency in your routine. 

Avoid smoking and excessive alcohol consumption 

Studies suggest the composition of the gut microbiome depends on a number of factors, including drug use, nicotine use and alcohol consumption. For this reason, avoiding these potentially harmful substances can help to improve your gut health and overall health. You may find more helpful information in our article: The Complex Relationship Between ADHD and Alcohol

Where can someone with ADHD seek support? 

If you or a loved one has ADHD, or you think you might have and would like to access support and treatment, there are a number of ways you can do this. It is incredibly important to seek personalised advice on managing your ADHD symptoms, as these are usually different for everyone. By doing this, you can also discuss how your gut health could be impacting your symptoms and what to do about this. 

Although research on gut health as an ADHD treatment is still in the early stages, there are certainly signs pointing to its potential benefits. If you would like to explore this as a treatment option for you, this is best done as part of a comprehensive, holistic approach to managing your ADHD. This means exploring the potential benefits of improving your gut microbiome using some of the tips mentioned above, as well as seeking professional guidance to ensure you are not overlooking key treatments that can provide more immediate benefits, such as medication. You can read more in our guide to ADHD medication in the UK.

You can speak to your GP about treatment options, or if you would like to access support without being added to a potentially long NHS waiting list, you can speak to a private provider like us at Augmentive. We can support you in your journey to obtain an ADHD diagnosis (if applicable) and provide treatment options for this, while also supporting you in visiting your GP or a private nutritionist to explore your options for more general dietary help.

Whether you’re feeling off-kilter or want to shake up your routine, our state-of-the-art mental wellbeing platform gives you quick and seamless access to world-class support on your terms, from a private adult ADHD assessment to help finding an ADHD specialist near you.

We believe all advice and support for those with ADHD should be personalised to each person’s individual situation, and our free 15 minute consultation can help match you with an appropriate professional who can help you.