Scientists have discovered that a fungus called Aspergillus oryzae—the same microorganism used to make soy sauce, miso, and sake—produces a special compound called agmatine that may help protect your brain and support gut health. This review explains how researchers found this fungus makes agmatine through a unique process, and why this discovery could lead to healthier fermented foods. The findings are exciting because they show that fermented foods might naturally contain more of this beneficial compound than we previously thought, potentially offering health benefits through the connection between your gut and brain.

The Quick Take

  • What they studied: How a fungus used in traditional Japanese cooking produces a natural compound called agmatine that may be good for brain health and overall wellness
  • Who participated: This is a review article that summarizes existing research rather than a study with human participants. Scientists examined previous studies about Aspergillus oryzae and agmatine production
  • Key finding: Aspergillus oryzae produces high amounts of agmatine when grown in solid-state conditions (like on rice or grain), and researchers identified the specific enzyme responsible for this production
  • What it means for you: Traditional fermented foods like miso and soy sauce may naturally contain beneficial compounds that support brain and gut health. This could mean these foods offer more health benefits than previously recognized, though more research in humans is needed to confirm the benefits

The Research Details

This is a review article, which means scientists gathered and summarized information from many previous studies rather than conducting a new experiment. The researchers looked at what’s known about how Aspergillus oryzae (a fungus used in Japanese cooking for centuries) produces agmatine, a natural compound in the body. They focused on understanding the specific enzyme that makes this happen and how it works differently than in other organisms. By reviewing existing research, they created a comprehensive overview of current knowledge and identified gaps where more research is needed.

Review articles are important because they help scientists and the public understand what we know about a topic and what questions still need answers. By summarizing previous research, this review provides a foundation for future studies and helps explain why fermented foods might be healthier than we thought. Understanding how the fungus makes agmatine could help food scientists create even more nutritious fermented foods.

This is a scientific review published in a peer-reviewed journal called Amino Acids, which means other experts checked the work. However, because this is a review rather than original research, it summarizes other studies rather than providing new experimental data. The strength of the findings depends on the quality of the studies being reviewed. Readers should note that while the fungus clearly produces agmatine, the health benefits in humans still need more research.

What the Results Show

The main discovery is that Aspergillus oryzae produces surprisingly high amounts of agmatine when grown in solid-state conditions (like on grain or rice), but produces very little when grown in liquid conditions. Researchers identified a specific enzyme called Ao-ADC1 that is responsible for making agmatine in this fungus. This enzyme works differently than similar enzymes in other organisms, which is why this discovery was surprising to scientists. The findings show that this fungus has a unique biological pathway for making agmatine that wasn’t previously understood.

The research also revealed that agmatine appears to have multiple health benefits, including protecting nerve cells in the brain, helping with lifestyle-related diseases, and supporting the connection between gut health and brain function. Additionally, the findings challenge what scientists previously believed about fungi—they thought fungi in the ascomycete family couldn’t make this enzyme, but Aspergillus oryzae clearly can. This opens up new possibilities for understanding how fermented foods contribute to health.

Previous research showed that humans can make some agmatine in their bodies, but not very much. Scientists also knew that gut bacteria and diet contribute to agmatine levels in the body. This review adds to that knowledge by showing that fermented foods made with Aspergillus oryzae are likely a significant dietary source of agmatine. It also corrects a misconception in the scientific community about which organisms can produce this enzyme.

Since this is a review article rather than original research, it summarizes what other studies have found rather than providing new experimental evidence. Most of the health benefits described have been studied in laboratory settings or animals, not yet thoroughly tested in humans. The review focuses on how the fungus makes agmatine but doesn’t provide complete information about how much agmatine ends up in finished fermented foods or how much humans actually absorb from eating these foods. More human studies are needed to confirm the health benefits.

The Bottom Line

Based on current evidence, eating traditional fermented foods like miso, soy sauce, and sake as part of a balanced diet appears safe and may offer health benefits through their natural agmatine content. However, these foods should not be used as a replacement for medical treatment. The evidence is moderate—we know the fungus makes agmatine, but we need more human studies to confirm specific health benefits. People interested in gut-brain health may benefit from including fermented foods in their diet, but this should be one part of an overall healthy lifestyle.

Anyone interested in brain health, gut health, or the nutritional benefits of fermented foods should find this interesting. People with lifestyle-related diseases like diabetes or heart disease may want to learn more, though they should consult their doctor before making dietary changes. This is less relevant for people who don’t eat fermented foods or who have specific allergies to these products. Researchers and food scientists should care about these findings because they could lead to developing new fermented foods with enhanced health benefits.

If you start eating more fermented foods, you won’t notice dramatic changes overnight. Health benefits from dietary changes typically take weeks to months to become noticeable. The gut-brain connection works gradually, so patience is important. Some people might notice improved digestion or mood within a few weeks, while other benefits might take longer to appear.

Want to Apply This Research?

  • Track daily servings of fermented foods (miso soup, soy sauce, tempeh, kimchi) and note any changes in digestion, mood, or energy levels over 4-8 weeks. Record specific amounts and types of fermented foods consumed.
  • Add one serving of a fermented food to your daily diet—this could be a spoonful of miso in soup, a small amount of soy sauce on rice, or a side of kimchi. Start small and gradually increase as your body adjusts.
  • Use the app to log fermented food intake weekly and track subjective wellness markers like energy, digestion, and mood. Create a simple 1-10 scale for how you feel and note any patterns that emerge over 8-12 weeks. Share results with a healthcare provider if making significant dietary changes.

This article summarizes scientific research about agmatine production in fermented foods and is for educational purposes only. It is not medical advice and should not replace consultation with a healthcare provider. While fermented foods are generally safe for most people, those with specific health conditions, allergies, or taking medications should consult their doctor before significantly changing their diet. The health benefits described are based on preliminary research; more human studies are needed to confirm specific therapeutic effects. If you have concerns about your health or are considering fermented foods as part of a treatment plan, please speak with a qualified healthcare professional.