Why the gut keeps coming up in ADHD

If you or your child has ADHD, chances are most of the focus so far has been on the brain. Medications, strategies, routines, sensory tools. And all of that absolutely has its place. But there’s another system worth paying serious attention to, and it lives a lot further south.

The gut.

Over the last decade, research into ADHD gut health has grown enormously. What’s emerging is genuinely fascinating: the gut communicates constantly with the brain, produces a significant portion of the body’s neurotransmitters, and houses an immune system that can either support or undermine how we think, focus and feel. When the gut is struggling, the brain often is too.

In clinic, I see this pattern regularly. Kids and adults with ADHD who also deal with constipation, bloating, food sensitivities, or a history of frequent antibiotic use. It’s rarely a coincidence.

The gut-brain axis: a two-way conversation

The gut-brain axis is a sophisticated communication network linking the digestive system and the central nervous system. It works through the vagus nerve, the enteric nervous system (the gut’s own independent nerve network), immune signalling, and hormonal pathways.

The vagus nerve is the superhighway of this system. Here’s what surprises most people: roughly 80 to 90 percent of the signals travelling along it go from the gut up to the brain, not the other way around. The gut is quite literally briefing the brain all day long.

For people with ADHD, vagal tone — how efficiently the vagus nerve functions — is an area of growing research interest. Poor vagal tone has been associated with difficulty regulating the nervous system, increased impulsivity, emotional dysregulation, and reduced attentional control.

The enteric nervous system adds another layer. This network of over 500 million neurons lining the gut wall operates largely independently of the brain. When its environment is disrupted, the signals it sends upstream change accordingly.

The microbiome and ADHD: what your gut bacteria are doing

The gut microbiome — the trillions of bacteria and other microorganisms living in the digestive tract — has an outsized influence on brain function. Here’s how:

Leaky gut, neuroinflammation, and ADHD

The gut lining is designed to be selectively permeable — allowing nutrients through while keeping bacteria, toxins, and larger molecules out. When that lining becomes compromised (leaky gut), things get through that shouldn’t.

This triggers an immune response. Inflammatory signalling compounds called cytokines increase in circulation, and inflammation begins to affect the brain as well as the gut. This state of neuroinflammation is increasingly understood as a meaningful contributing factor in ADHD symptoms.

The current model gaining traction in research: gut dysbiosis leads to increased intestinal permeability → systemic inflammation → impaired blood-brain barrier function → neurological environment associated with worsening of symptoms associated with ADHD. It’s not the whole picture, but it’s a significant part of it.

Microbiome testing: actually seeing what’s going on

One of the most valuable things we can do when ADHD and gut symptoms overlap is to look at what’s actually happening in the microbiome — rather than applying a generic protocol and hoping for the best.

This is where I find gut microbiome testing genuinely useful. I currently use Microba, a gut testing service that uses deep shotgun metagenomic sequencing — a significantly more detailed method than standard testing. Rather than just identifying which bacterial families are present, it can identify bacteria at the species and strain level, measure functional capacity, and assess markers like SCFA-producing potential and inflammation-related species and metabolites.

Testing is done at home with a stool sample and returned to the lab via post — straightforward for both adults and kids. The results are detailed but translated into accessible language, which I find really useful for explaining findings to patients.

This information takes the guesswork out of gut support. Rather than applying a one-size-fits-all approach, we can see exactly where the gaps are and tailor support accordingly — specific probiotic strains, prebiotic foods, dietary shifts, and targeted herbal or nutritional support where indicated.

It currently costs ~$400-$500 depending on which level of test you choose which is not feasible for some people, but certainly gut health work can still be done without this, just not with the same level of fine tuning.

Common questions about ADHD and gut health

If you’ve recently received an HPV diagnosis, first things first — take a breath. A positive result can feel alarming, but the reality is that HPV is incredibly common, and for most people, the immune system clears it on its own.

That said, there’s a lot you can do to support that process. Here’s what I want you to understand about HPV, and how a naturopathic approach can complement your conventional care.

First, the reassuring part

HPV is incredibly common — most sexually active people will encounter it at some point in their lives. The immune system clears the virus on its own in roughly 70% of cases within 12 months, and around 90% of cases within two years.

There are over 100 subtypes of HPV, and only a small number — primarily types 16 and 18 — are associated with the kind of cell changes that can progress toward cancer over time. Persistent infection over many years, rather than a single positive result, is what’s associated with higher-grade changes. This is why regular cervical screening is so important, and why early detection matters.

How HPV actually works

HPV works by targeting the body’s natural tumour-suppressing genes, typically at a site of micro-trauma in the cervical tissue. Certain high-risk subtypes carry what are called E6 and E7 oncogenes, which essentially interfere with those protective mechanisms. This is why supporting immune function — your body’s ability to recognise and respond to the virus — is so central to a naturopathic approach to cervical health.

The good news is that immune function is highly modifiable. What you eat, how you sleep, what you’re exposed to, and the state of your microbiome all play a meaningful role.

What influences your immune response to HPV?

Research points to several modifiable factors that influence whether HPV persists or clears. Here’s what’s worth understanding:

What a naturopathic approach looks like

Naturopathic support for HPV isn’t about replacing your gynaecological care — it works alongside it. The focus is on identifying and addressing the factors unique to you that may be influencing your immune response, supporting the body’s natural clearance mechanisms, and reducing overall risk where possible.

This might include:

Nutritional and dietary support — tailoring your diet to support immune function, methylation, and healthy oestrogen metabolism, with specific foods and nutrients that research supports for cervical health.

Targeted supplementation — based on your individual presentation, testing, and health history.

Microbiome support — including the use of custom-compounded vaginal pessaries where appropriate. These can be formulated with anti-viral properties and beneficial bacteria to help reduce viral load and support a healthy vaginal environment. In some cases, a comprehensive vaginal microbiome test may also be recommended to get a full picture of what’s happening at a microbial level and guide treatment more precisely.

Related Reading: What to do when Thrush and BV don’t go away

Stress and sleep support — because a nervous system under chronic load is a significant barrier to immune function, and this is often the piece that gets missed in conventional care.

Reducing environmental exposures — practical, evidence-informed guidance on the changes that will make the most difference for your situation.

Please don’t skip your cervical screening

Whatever else you are doing, please keep up with your regular cervical screening appointments. Screening is what allows us to catch any cell changes early, when they are most straightforward to manage. It remains one of the single most important things you can do for your cervical health — and it works best when done consistently over time.