You may have heard the term “leaky gut” thrown around in wellness spaces. While it’s not a diagnosis most medical professionals use or accept, the issue people are referring to is very real: intestinal hyperpermeability, a condition where the lining of the gut becomes less effective at keeping out what does not belong in the bloodstream.
It also means the gut lining is less effective at keeping things in, including beneficial gut bacteria that help us create ALL the B vitamins as well as vitamin K2. Our gut bacteria are also necessary to create short-chain fatty acids like butyrate which play a key role in managing inflammation.
While it may seem like a wellness grift, there is some evidence to back up the connection between ‘leaky gut’ and ADHD—specifically in people with AuDHD (Autism + ADHD). Let’s talk about it.
What is intestinal hyperpermeability?
Your gut lining is made of cells that are tightly joined together, forming a protective barrier. This barrier functions like a coffee filter, selectively allowing nutrients to pass through while blocking larger toxins, pathogens, and unwanted particles from entering your bloodstream.
In cases of intestinal hyperpermeability, these tight junctions begin to loosen. This allows unwanted substances—food antigens (think allergies), bacterial components, and toxins—to “leak” into the bloodstream.
This can trigger the immune system and result in low-grade chronic inflammation, which is connected to ADHD. Hyperpermeability can also impair the absorption of essential nutrients like vitamins, minerals, and amino acids, which are crucial for brain function and overall health.
What the research says
One 2023 study found that a subgroup of children with both ADHD and Autism Spectrum Disorder (ASD) had elevated levels of a protein called lipopolysaccharide-binding protein (LBP), a marker that suggests the gut barrier may be compromised. These same children also had higher levels of immune molecules like cytokines, pointing toward a systemic immune response likely driven by microbial products crossing the gut wall.
This could mean that, in some cases, the gut lining of children with ADHD or ASD is not working properly, allowing bacteria or toxins to leak into the bloodstream and trigger immune system responses. Researchers believe this constant low-level inflammation could contribute to ADHD symptoms, which are often associated with brain dysfunction and neuroinflammation.
Interestingly, the study found no significant differences in fecal calprotectin, a marker often used to identify inflammatory bowel diseases, which suggests that the disruptions in gut permeability were not due to conditions like IBS (Inflammatory Bowel Syndrome). The study also found disruptions were not related to diet. Instead, the increased LBP (lipopolysaccharide-binding protein) levels pointed specifically to the idea of a more genetically predicted “leaky” gut.
Possible symptoms of gut barrier dysfunction
There is no single symptom checklist, but below are some identifiers of increased intestinal permeability. These are non-specific, so they don’t confirm a “leaky gut” on their own—but in combination with ADHD or ASD traits, they may offer clues:
- Digestive discomfort (bloating, irregular bowel movements)
- Brain fog or fatigue after eating
- Chronic low mood or irritability
- Food sensitivities
- Frequent immune system activation (e.g., frequent colds, inflammation markers)
Why gut dysfunction matters for ADHD
Clearly, our guts have a big impact on our ADHD brains (and vice versa): The gut plays a powerful role in modulating neurotransmitters, nutrient absorption, and the immune system—all of which can affect ADHD symptoms. A more permeable gut lining could potentially:
- Allow inflammatory signals to influence the brain
- Reduce absorption of nutrients critical for neurotransmitter function (like zinc, magnesium, folate, and B6)
- Aggravate dopamine regulation through immune-related pathways
For some individuals with ADHD, especially those with co-occurring ASD or digestive concerns, supporting the gut barrier may lead to noticeable benefits in focus, mood, and overall regulation.
What to do if you suspect “leaky gut”
You don’t need to test for intestinal permeability to start making gut-friendly shifts. Supporting your intestinal barrier looks a lot like supporting your microbiome in general:
- Reduce stress
- Eat more plants
- Get enough sleep
- Move your body after meals
- Cut down on ibuprofen, proton-pump inhibitors, alcohol, and ultra-processed foods
According to the research, most people with ADHD do not have gut permeability issues. But for those who do, it can significantly affect their mood, inflammation, and immune system responses. The good news? Even small, consistent shifts in food and lifestyle can begin to restore balance, one meal and moment at a time. Dive deeper by reading my article on 6 Easy Food Strategies to Support Your ADHD Gut.
