Royal jelly compound calms autism-like behavior in mice by resetting gut bacteria

If you've ever wondered whether something as basic as gut bacteria could reach all the way into brain development, a new mouse study offers one of the most detailed mechanistic answers yet. Researchers studying a royal jelly compound called 10-HDA (10-hydroxy-2-decenoic acid, a fatty acid that is the main active ingredient in the substance worker bees feed to future queens) found it eased autism-like social withdrawal and repetitive behavior in mice. It did this not by acting on the brain directly, but by reshaping gut bacteria that in turn dial down an inflammatory signal and rebalance the immune system. The finding matters because autism spectrum disorder (ASD) now affects an estimated 1 in 31 children in the United States, according to the CDC, and treatments targeting the condition's core symptoms remain scarce.

Key takeaways

• A compound from royal jelly, 10-HDA, eased autism-like social and repetitive behaviors in a mouse model of autism, and a fecal transplant from 10-HDA-treated mice alone reproduced the benefit in other mice.
• The effect ran through the immune system: 10-HDA restored the balance between inflammatory Th17 cells and calming regulatory T cells (Tregs), and removing Tregs erased the behavioral benefit entirely.
• This is a preprint mouse study, not yet peer-reviewed and not a human treatment; the underlying mechanism, gut microbes shaping immune-brain crosstalk, is worth watching rather than acting on today.

Royal Jelly's 10-HDA Compound Eased Autism-Like Behavior in Mice

Researchers led by a team at Hefei University of Technology tested royal jelly and its components in BTBR mice, an inbred strain that naturally shows the low sociability and repetitive habits used to model autism spectrum disorder in rodents. Daily doses of whole royal jelly, sourced from two different regions of China, increased how much time the mice spent interacting with an unfamiliar mouse and reduced compulsive marble-burying, a standard stand-in for repetitive behavior. When the researchers isolated royal jelly's separate protein and fatty-acid fractions, only the fatty-acid fraction worked. Narrowing further, a single fatty acid, 10-HDA, reproduced the full effect on its own at a dose of 100 mg/kg, while a closely related molecule, 10-HDAA, did nothing. That specificity is what let the team focus the rest of the study on 10-HDA as the active ingredient.

Why an Immune Imbalance Seen in Autism Patients Matters Here

People with autism spectrum disorder have repeatedly been found to carry an immune imbalance: too few regulatory T cells (Tregs, immune cells that calm inflammation) and too many Th17 cells (immune cells that promote it), a pattern that tracks with the severity of social symptoms in prior human research on gut microbiota's effect on the Treg/Th17 balance. The BTBR mice in this study showed the same skew relative to normal control mice, and both whole royal jelly and isolated 10-HDA corrected it. To find out whether that correction actually caused the behavioral improvement, the researchers depleted Tregs in 10-HDA-treated mice using an antibody. The pro-social and anti-repetitive effects of 10-HDA disappeared almost entirely once Tregs were gone, which is strong evidence that restoring this immune population, not some side effect, is what drives the behavioral rescue.

Fecal Transplants and an Antibody Nailed Down the Gut-Immune Link

To show that gut bacteria, rather than 10-HDA acting directly on immune cells, were doing the mediating, the team ran a fecal microbiota transplant (FMT). Mice that received fecal matter from 10-HDA-treated donors showed clear improvements in sociability and repetitive behavior compared with mice given control transplants, even though the recipients themselves never received the compound. The reverse experiment confirmed it: wiping out the gut microbiome with the antibiotic vancomycin in 10-HDA-treated mice blocked the Treg expansion and let Th17 levels climb back up. The researchers then traced the chain one step further to interleukin-6 (IL-6, an inflammatory signaling protein): BTBR mice had elevated blood IL-6 that 10-HDA reversed, and depleting the microbiome reversed that reversal, pointing to gut bacteria as the source of the excess IL-6. Blocking IL-6 directly with an antibody reproduced 10-HDA's calming effects on behavior on its own, closing the loop from microbiome to cytokine to immune balance to behavior. The team's related work in this space builds on a broader body of research into how regulatory T cells traffic along the gut-brain axis more generally.

The researchers pushed even deeper into cellular mechanism, isolating immune cells and treating them with 10-HDA directly in a dish. There, 10-HDA suppressed a gene called Kmt2b (a chromatin-modifying enzyme) in cells being pushed toward the calming Treg fate, while boosting it in cells pushed toward the inflammatory Th17 fate. Blocking Kmt2b with genetic tools alone increased Treg formation, confirming it functions as a brake on the calming immune pathway that 10-HDA releases. Genome-wide sequencing showed 10-HDA reshapes two opposing chemical tags on DNA-packaging proteins, adding an activating tag at the gene for the anti-inflammatory signal IL-10 while adding a silencing tag at the gene for the inflammatory signal IL-17.

What This Means If You're Watching Autism Research Closely

None of this means royal jelly or 10-HDA supplements belong in an autism treatment plan today; the study was conducted entirely in mice, using injected antibodies and lab-grade doses that have no established human equivalent, and no one should give a child royal jelly, or any supplement, expecting an effect on autism symptoms. What the study adds is a mechanistic map connecting three things researchers already suspected were tangled together in ASD, gut bacteria, immune balance, and brain-relevant behavior, into one causal chain, tested rather than merely observed. For a family already following the science on gut-immune-brain connections in autism, this is a data point that the microbiome-immune route is a biologically real pathway, not simply a correlation. It is not, on its own, a reason to change diet, supplements, or care for a person with autism.

What's Not Yet Known

This is a preprint posted to Research Square and has not yet been peer-reviewed. Group sizes were small, typically five or six mice per group, from a single laboratory, and only male mice were tested, so the findings need independent replication before they carry much weight. The behavioral tests used, a three-chamber sociability test and a marble-burying test, are standard in autism mouse research but are indirect proxies for the much more varied presentation of autism in humans. The authors themselves note that disentangling how much of 10-HDA's effect comes from its direct action on immune cells versus its effect through gut microbes will require further work, including germ-free mouse models.

What Comes Next

The authors call for targeted metabolomics and germ-free mouse experiments to pin down exactly how much of 10-HDA's benefit runs through the gut versus direct immune action, and for peer review of the current findings. Any path toward human relevance would require dedicated human trials establishing safety and dosing, work that has not been done and was not part of this study.

Common Questions

What is 10-HDA? It is 10-hydroxy-2-decenoic acid, a fatty acid that makes up much of royal jelly, the food worker honeybees produce to raise queen bees. It has been studied previously for various immune and neuroprotective effects.

Does this mean royal jelly can treat autism in people? No. This is a preclinical mouse study using a specific idiopathic-autism mouse strain (BTBR) and lab-controlled doses; it does not establish a treatment for people, and there is no human safety or dosing data for this purpose.

How exactly does gut bacteria affect behavior in this study? 10-HDA changes the gut microbiome, which lowers a bacteria-linked inflammatory signal (IL-6) in the blood, which in turn shifts the ratio of calming regulatory T cells to inflammatory Th17 cells, and that immune shift is required for the behavioral improvement, since removing those calming cells erased the benefit.

Is this study peer-reviewed? No. It is currently posted as a preprint on Research Square and has not yet completed peer review.

References

1. Yi Xu, Feng Zhu, Ruili Yang, et al. (2026). 10-HDA from royal jelly ameliorates autism-like behaviors by promoting Treg commitment through microbiota-IL-6-driven bivalent histone remodeling. https://doi.org/10.21203/rs.3.rs-10498580/v1
2. Data and Statistics on Autism Spectrum Disorder | CDC. cdc.gov. https://www.cdc.gov/autism/data-research/index.html
3. Guolin Li, Yu Xiong, Zhimin Li, et al. (2025). Gut microbiota-derived metabolites modulate Treg/Th17 balance: novel therapeutic targets in autoimmune diseases. Frontiers in Immunology. https://doi.org/10.3389/fimmu.2025.1710733
4. Juli Choi, Bo-Ram Kim, Begum Akuzum, Leechung Chang, June-Yong Lee, Ho-Keun Kwon (2022). TREGking From Gut to Brain: The Control of Regulatory T Cells Along the Gut-Brain Axis. Frontiers in Immunology. https://doi.org/10.3389/fimmu.2022.916066