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A new series of health insights is on the way.
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Anxiety, depression, epilepsy, and even Alzheimer’s disease share a surprising common thread: low levels of a neurotransmitter called GABA. Short for gamma-aminobutyric acid, GABA acts as your brain’s primary “brake pedal,” slowing down over-firing and returning your nervous system to a calm, steady state.
When this neurotransmitter is out of balance, symptoms include racing thoughts, poor sleep, panic attacks, memory problems, and seizures. Many people think of GABA as a brain chemical made only in the brain. But a growing body of research is showing that your gut microbiome plays an important role in how much GABA your brain produces.
In fact, a study published in NPJ Science of Food found that certain types of prebiotics—not just probiotics—raise GABA levels in your gut and, more importantly, in your brain.1 This is important because GABA isn’t just for relaxation—it helps regulate everything from mood to cognition to immune responses.
If your gut microbiome doesn’t support adequate GABA production, you may find yourself stuck in chronic stress, emotional instability, or cognitive fog. You may be eating well and getting enough sleep, but you still feel like something is missing.
The root cause may be in your microbiome – and the fix may be as simple as restoring the proper bacterial balance. Let’s take a closer look at how this research has revealed the gut-brain connection that drives GABA production and why it can change the way you look at mental health from the inside out.
Prebiotics change GABA to increase gut bacteria in your brain
Researchers at NPJ Food Science have investigated whether fructooligosaccharides (FOS), a popular prebiotic, and enzymes from a fungus called Aspergillus can promote weight gain. GABA And homocarnosine – a compound found primarily in the brain, made from GABA, that helps keep brain cells healthy and your brain healthy.2 Probiotics have been shown to increase gut and brain GABA, researchers wanted to know if prebiotics could do the same – and how.
• The study looked at brain and gut effects using adolescent mice. The researchers fed adolescent mice either FOS, Aspergillus lipase or Aspergillus protease for four weeks. They then measured levels of GABA and homocarnosine in the gut, blood and brain. They also analyzed the gut microbiome to determine which bacterial changes explained the changes in neurotransmitter levels.
• FOS and enzymes increased brain GABA levels in several regions: All three treatments – FOS, lipase and protease – increased GABA levels in the brain, especially in the cortex and hippocampus, two regions associated with memory, stress and emotional balance. Fos is a key regulator of hormones and increased GABA in the hypothalamus of autonomic nervous system activity.
• Homocarnosine, a GABA-based brain peptide, also increased – Along with high GABA levels, the researchers found a significant increase in homocarnosine in the hippocampus in all treatment groups. Homocarnosine plays an important role in nerve function. Increases in both compounds indicate profound changes in brain chemistry linked to the activity of microbial activity in the gut.
• GABA is not absorbed in the blood, suggesting a non-blood communication pathway – Interestingly, none of the treatments elevated GABA in the blood. This suggests that gut-produced GABA may signal to the brain through other pathways, perhaps via the vagus nerve or hormonal pathways, rather than circulating in the bloodstream.
Beneficial bacteria have increased with GABA
After the treatment, the gut microbiome changed in measurable ways. FOS and enzymes increased important species such as Parabacteroides, Ackermansia, Muribaculum and Hungatela. These specific bacteria showed strong positive correlations with high GABA and homocarnosine in the brain. They are now considered “assistant species” in this gut-brain communication network.
• Other types of bacteria have fallen — and that’s a good thing — Bacteria negatively associated with GABA and homocarnosine, including Bluetia, Roseburia, and Eubacterium coprostanoligenes, decreased in abundance after FOS and enzyme supplementation. These species are often elevated in gut dysbiosis and can disrupt healthy neurotransmitter production.
• FOS has a significant effect on the intestinal environment – While all three supplements increased brain GABA, FOS induced the most significant changes in gut microbial composition and diversity. Relative abundance of Bacterodota and Verrucomicrobiota – microbial phyla linked to metabolic health – and Firmicutes, a group often associated with inflammation when out of balance, is reduced.
• Aspergillus enzymes act as probiotics in shaping the gut microbiome: Although not a traditional fiber, the fungal enzymes used in the study showed prebiotic-like behavior. They probably work by breaking down undigested macronutrients in the large intestine and releasing nutrients that feed the GABA-supporting bacteria.
• Bacterial changes are directly linked to neurotransmitter levels: Using correlation analysis, researchers found that certain bacterial populations – especially Akkermansia, Parabacteroides and Flavonifera – were strongly linked to GABA and homocarnosine levels. Meanwhile, species such as Colidextribacter and Acetatifactor were associated with lower levels. These patterns help determine which microbes play supportive and repressive roles in GABA metabolism.
How to restore GABA balance by healing your gut
If your mental energy feels unstable — too wired during the day, too rested at night — your GABA levels may be out of sync. And that imbalance often starts in the gut. Even “healthy” foods like prebiotics can worsen symptoms when your microbiome is compromised. But when your gut is stable, the right prebiotics can be powerful tools for restoring calm and focus by increasing brain GABA. The main thing is to know when and how to use them. Here are five steps to help you get there.
1. Don’t go on prebiotics if your gut is inflamed – If you feel gassy, bloated, or irregular after eating, your gut lining is probably irritated and your microbiome is out of balance. This is not the time to load up on garlic, onions or leeks. These ferment very quickly and feed on harmful endotoxin-producing bacteria, which worsen symptoms. Instead, go with metabolically safe carbs like white rice and fruit, which will nourish you without feeding the wrong bacteria.
2. Wait for symptoms to settle before adding fermentable carbohydrates – Most people move in quickly. Fiber Always thinking it’s a good thing. But when your gut lining is compromised, even resistant starches and “gut-friendly” fiber can do more harm than good. Once you have regular bowel movements with no bloating, that’s your green light to start introducing prebiotics slowly and purposefully.
3. Support GABA with food-based prebiotics – at the right time – As your digestion strengthens, begin introducing prebiotic foods that support GABA-producing bacteria. These include FOS-rich choices such as bananas, asparagus, garlic and leeks. The goal isn’t to flood your system, but to gently nudge the right species, like Akkermansia, into the balance. All you need to get started is a quarter of a ripe leek or a few slices of a ripe banana.
4. Boost brain GABA with processed foods and targeted supplements – Once you achieve microbial stability, begin layering on direct GABA support. Bready foods like kimchi, kefir, and miso contain a small but significant amount of GABA. If your anxiety is high or your sleep is poor, consider a high-quality GABA supplement.
5. Use natural progesterone to increase the calming effect of GABA: Natural progesterone improves GABA signaling in the brain and has a direct calming effect on your nervous system. Unlike synthetic progesterone, natural progesterone is a hormone that your body already recognizes and responds to.
Questions about Prebiotics and GABA
Q: How does your gut microbiome affect GABA levels in your brain?
A: Your gut bacteria play a key role in producing GABA, your brain’s main calming neurotransmitter. Some beneficial microbes like Akkermansia and Parabacteroides help increase GABA and its brain-based partner, homocarnosine. When these microbes are supported with the right prebiotics, GABA levels are increased in brain regions linked to memory, stress and mood regulation, helping to reduce stress, improve sleep and support cognitive clarity.
Q: What are the best prebiotics to increase brain GABA?
A: Fructooligosaccharides (FOS), found in foods such as garlic, onions, leeks, bananas and asparagus, support GABA-producing microbes. Enzymes derived from the Aspergillus fungus, particularly proteases and lipases, also act as prebiotics by shaping the gut microbiome and feeding the right bacteria without the overgrowth that causes gas or bloating.
Q: Should you take prebiotics if your gut is sick or damaged?
A: Not yet. If you have bloating, constipation, or loose stools, your gut is not ready for high prebiotic foods. In this case, prebiotics feed the wrong microbes and increase inflammation. It’s best to start with metabolism-boosting carbs like white rice and fruit, then gradually introduce prebiotics once your digestion has stabilized.
Q: Besides prebiotics, what natural strategies help increase GABA?
A: Bready foods like kimchi, kefir, and miso directly provide small amounts of GABA. Supplements provide additional targeted support if your levels are depleted. Natural progesterone enhances the calming effects of GABA in your brain, which can help reduce the wired-but-fatigue feelings that often come from hormonal imbalances or severe stress.
Q: What does homocarnosine do, and why is it important?
A: Homocarnosine is a brain-specific compound made from GABA and histidine. It helps protect neurons, stabilize brain chemistry and supports clear thinking. The same prebiotics that increase brain GABA also increase homocarnosine levels, making them doubly important for improving neural health via the gut-brain axis.
