When was the last time you had butterflies in your stomach? A crush, or maybe your boss got snippy with you—your brain was having a strong feeling, and your gut responded. This isn’t a trick; your gut is the largest ecosystem in your body.
In recent years, the gut-brain connection has been getting a lot of attention, especially in conversations around ADHD. Headlines suggest that the gut microbiome could be causing ADHD, or that probiotics might “fix” it. But what does the science say?
What is the gut-brain axis, and why does it matter for ADHD?
The gut and the brain are in constant conversation. This system, called the gut-brain axis, works in two directions. When something shifts in the gut microbiota, it affects our brains—and vice versa. Your “gut feelings” and “gut reactions” are very real: in fact, our gut microbiome influences our blood-brain barrier itself!
For instance, serotonin helps us understand when we’re hungry and can slow down our digestion.
Everything we currently know about the ADHD gut microbiome
A 2025 meta-analysis reviewed all the studies done on ADHD and the gut. Here’s a breakdown of the key findings.
- Diversity of Bacteria: Bacterial diversity is one of the most important markers of gut health, and some studies have connected poor gut health in youth to ADHD.
- The meta-analysis showed people with ADHD didn’t have “more” or “less” gut diversity overall. So, a diverse gut environment isn’t the issue, but as usual, there’s always more to look at.
- There were no strong, consistent relationships between specific gut microbes and ADHD symptom severity.
- A few random correlations popped up, but not enough to draw conclusions.
What’s a diverse gut?
Neither alpha nor beta diversity were consistently different in people with ADHD.
Microbial function might be the missing link
Now remember: ADHD is complex. Despite the conflicting information, there are important things we can get from the study. Instead of looking at the diversity or the presence of the different species, researchers are starting to look at what those bacteria are doing.
In the analysis, the microbial functions that differed most in people with ADHD compared to people without ADHD were tied to nutrients that are all closely linked to brain health—and in particular, to the neurotransmitters involved in ADHD:
- Protein metabolism: The brain uses amino acids from the protein you eat to create neurotransmitters like dopamine and serotonin. There were differences in how the ADHD body used protein.
- Folate synthesis: Folate creates something called SAMe, an enzyme necessary to create and break down our neurotransmitters. We saw microbial differences in the metabolism of folate.
- Vitamin B6 pathways: B6 is a critical cofactor—aka absolutely necessary—in creating dopamine and serotonin. If you don’t have enough, or if your body doesn’t absorb it effectively, your neurotransmitter creation declines! Again, we saw differences in microbial metabolism of B6.
What this research means for your ADHD
The bottom line? The gut microbiome may play a role in ADHD, but not in the “every person with ADHD needs to buy this specific probiotic” kind of way. There is no magic probiotic that works for everyone, no guaranteed microbiome “fix.”
But supporting your gut health, especially in ways that promote neurotransmitter and nutrient production, might be a small, helpful piece of your ADHD puzzle. If you’re curious about some action steps, here are the 6 Ways to Help Your ADHD Gut Microbiome Using Food.
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