Gram Research analysis of a 2026 study in Gut Microbes found that a gut bacteria byproduct called indole-3-propionic acid (IPA) helps regulate blood sugar by changing how liver cells use fuel. In mice, IPA improved fasting blood sugar and glucose handling, and gut microbes that produced it raised blood levels and improved glucose tolerance. Human effects are not yet known.
Gram Research analysis of a 2026 study in the journal Gut Microbes suggests that a substance made by gut bacteria may help control blood sugar. The substance, called indole-3-propionic acid (IPA), is produced when gut microbes break down tryptophan, a protein building block found in foods like turkey, eggs, and oats. Researchers found that IPA changed how liver cells use their fuel, reducing the sugar the liver releases into the blood without shutting down the liver’s normal functions. In mice fed a Western diet, short-term IPA treatment improved fasting blood sugar and how well the animals handled sugar. Mice that received gut bacteria able to make IPA also had better blood sugar control than mice given a version of the bacteria that could not make it. These results come from lab and animal studies, so they do not yet show that IPA works the same way in people.
Key Statistics
A 2026 study published in the journal Gut Microbes found that indole-3-propionic acid, a substance made by gut bacteria from the protein tryptophan, improved fasting blood sugar and glucose handling in mice fed a Western diet.
In a 2026 mouse study, germ-depleted mice colonized with an IPA-producing strain of Clostridium sporogenes had higher circulating IPA and better glucose tolerance than mice colonized with an IPA-deficient mutant strain.
A 2026 laboratory study in primary liver cells found that IPA selectively reduced glucose output from mitochondria-dependent fuels while largely preserving glycerol-supported glucose production, suggesting it changes how liver cells use fuel rather than shutting down sugar production.
The Quick Take
- What they studied: Researchers wanted to know whether a substance made by gut bacteria from the protein tryptophan can directly affect how the liver makes sugar and how the body controls blood sugar.
- Who participated: The study used liver cells grown in the lab and laboratory mice, including mice fed a high-fat Western diet. The abstract does not report the exact number of animals or cell samples used.
- Key finding: IPA reduced sugar output from liver cells that rely on certain mitochondrial fuels, while leaving another sugar-making pathway largely intact. In mice, IPA improved fasting blood sugar and glucose handling, and gut bacteria that produced IPA raised blood IPA levels and improved glucose tolerance.
- What it means for you: This research points to a possible gut-to-liver link in blood sugar control, but it does not yet show that eating foods or taking supplements that raise IPA will help people. Anyone concerned about blood sugar should talk with a doctor rather than change their care based on this study.
The Research Details
The research began in the lab with liver cells called hepatocytes, which are the cells that produce sugar in the liver. The team tested a group of related gut-derived compounds, called indole metabolites, to see which ones lowered the sugar the cells released when stimulated by glucagon, a hormone that tells the liver to make and release sugar. IPA was selected for deeper study because of its strong effects.
Next, the researchers examined how IPA changed the cells’ energy use. They tracked which fuels the cells used to make sugar, such as lactate, glycerol, and other molecules, and measured signs of mitochondrial activity. Mitochondria are the parts of cells that produce energy. They also checked whether IPA interfered with insulin or glucagon signals, which appeared not to be the case.
Finally, the team tested the idea in living mice. They measured natural IPA levels under different feeding conditions, gave some mice IPA for a short period, and then used germ-free or antibiotic-treated mice that had their gut bacteria reduced. These mice were given either a normal IPA-producing strain of Clostridium sporogenes or a mutant strain that could not make IPA, and their blood IPA levels and glucose tolerance were compared.
Using cells, whole animals, and bacteria together helps separate what IPA does in a dish from what it does in a living body. The cell work shows a possible mechanism, the mouse diet and treatment work shows a possible effect on blood sugar, and the bacterial colonization work connects that effect to the gut microbes themselves. Each step supports the next, which makes the overall story more convincing than any single experiment alone.
The study combines several methods and tests the same idea in more than one setting, which is a strength. It appears to be a laboratory and animal study, so it cannot tell us how IPA affects people with diabetes or prediabetes. The abstract does not report sample sizes, statistical details, or how long the mouse treatments lasted, so readers should look at the full paper before drawing firm conclusions. Because the paper is from a peer-reviewed journal, it has been checked by outside experts, but it still needs to be repeated and confirmed by other teams and by human studies.
What the Results Show
The first major finding was that several indole compounds, including IPA, reduced the sugar liver cells released in response to glucagon. This suggests that gut-derived molecules can directly influence how liver cells make glucose, which is an important part of keeping blood sugar steady between meals.
IPA did not simply turn off the liver’s sugar factory. It selectively lowered sugar production from fuels that depend on mitochondria, the energy-producing parts of the cell, while keeping glycerol-based sugar production largely unchanged. The authors describe this as IPA changing how the liver uses its fuel rather than blocking sugar making entirely. This distinction matters because a complete shutdown of liver sugar production could be unsafe.
The researchers also found that IPA changed the cell’s internal energy balance, including redox balance, ATP availability, and activity linked to the urea cycle, which is the process the body uses to clear nitrogen waste. These changes happened without clear disruption of the insulin or glucagon signals that normally tell the liver what to do. Together, this points to IPA acting from inside the cell rather than by blocking hormone messages.
In mice, natural IPA levels shifted with feeding and fasting, and short-term IPA treatment improved fasting blood sugar and glucose handling in animals eating a Western diet. In germ-depleted mice, colonization with an IPA-producing strain of C. sporogenes raised blood IPA and improved glucose tolerance compared with a mutant strain that could not make IPA.
The study’s mouse results are significant because they connect the microbe, the molecule, and the body’s blood sugar control in one chain of evidence. When mice received a bacterium that could make IPA, their blood IPA rose and their sugar handling improved, which suggests that the gut microbes themselves, not just the molecule, can influence metabolism. This supports the idea that gut bacteria can be part of the picture in metabolic health.
The finding that IPA levels vary with nutritional state is also useful. It suggests the body’s own IPA production may respond to what and when we eat, which could help explain why diet affects blood sugar. Still, the abstract does not give the size of these changes, so their practical importance is unclear.
Previous research has linked gut bacteria and their metabolites to metabolic health, and tryptophan-derived molecules have been studied for their roles in the gut, immune system, and brain. This study adds a more specific piece by showing that one such molecule can act directly on liver cell metabolism. It fits with the growing view that the gut and liver communicate through chemical signals made by microbes, though human research on IPA and blood sugar is still limited.
The most important limitation is that most of the evidence comes from liver cells in the lab and from mice. Mouse metabolism differs from human metabolism in important ways, so the results may not carry over directly. The abstract also does not report how many animals were used, how long the treatments lasted, or what doses were given, which makes it harder to judge how strong or reliable the effects are. Finally, the study does not show whether IPA lowers the risk of diabetes or improves long-term health in people.
The Bottom Line
Based on this study alone, the evidence is preliminary, so no diet or supplement change should be made just because of it. The research gives moderate confidence that IPA can affect liver sugar production and mouse blood sugar in the lab, but low confidence that the same effect will occur in people. Future human trials would be needed before any practical recommendation could be made. People who want to support blood sugar health can rely on proven steps such as regular physical activity, balanced meals with fiber, and medical care for diabetes or prediabetes.
Researchers studying gut bacteria, liver metabolism, and diabetes should find this study especially useful, since it points to a possible new pathway to investigate. People with diabetes, prediabetes, or metabolic conditions may find it interesting, but they should not change medications or treatments based on these findings. Pregnant people, children, and anyone taking blood sugar medicine should speak with a healthcare professional before trying any product that claims to raise IPA.
Any real-world benefit from this line of research is likely years away. The next steps would include more animal studies, safety testing, and carefully designed human trials that measure blood sugar and IPA levels over months. Even if IPA proves useful, it could take many years before any treatment reaches clinics or the public.
Frequently Asked Questions
What is indole-3-propionic acid and how does it relate to blood sugar?
Indole-3-propionic acid, or IPA, is a substance that gut bacteria make when they break down the protein tryptophan. A 2026 study in Gut Microbes found that IPA changed how liver cells use fuel, reducing certain sugar release in lab tests and improving blood sugar handling in mice.
Can eating more tryptophan foods raise IPA and lower blood sugar?
The study did not test diet changes in people, so this is not yet proven. Tryptophan-rich foods such as eggs, poultry, oats, and beans supply the raw material for gut bacteria, but research has not shown that eating them will lower blood sugar through IPA in humans.
Has IPA been tested in human blood sugar trials?
Not in the 2026 study reviewed here, which used liver cells in the lab and laboratory mice. Human clinical trials are needed to show whether IPA affects blood sugar, diabetes risk, or long-term health in people.
Should I take an IPA supplement to control my blood sugar?
No supplement has been shown to safely control blood sugar in people based on this research. Anyone with diabetes or prediabetes should follow a doctor’s plan, since IPA’s safety and effectiveness in humans have not been established.
Want to Apply This Research?
- Track fasting blood sugar if you have a glucose meter or a doctor-recommended test, and log your average fasting reading once a week. Also record how many grams of fiber and how many servings of whole grains, eggs, poultry, and oats you eat each day, since these foods contain tryptophan, the starting material for IPA. Note any changes you see over at least four weeks.
- Use the app to set a reminder to include one whole-food protein source with each meal, such as eggs, poultry, oats, or beans, along with a vegetable or fiber-rich food. This supports healthy blood sugar habits that are already well supported by research. Avoid taking IPA supplements unless a doctor recommends them, because their safety and effects in people are not yet established.
- Review your weekly blood sugar averages and food logs every three months with your healthcare provider, especially if you have diabetes or prediabetes. Watch for new research on IPA and gut health, and update your app notes only when findings come from human studies or trusted medical sources. Keep a long-term record of energy levels, meal patterns, and any medical test results so you can see meaningful trends over time.
This article summarizes a laboratory and animal study on a gut bacteria byproduct and liver blood sugar regulation. The findings have not been tested in human clinical trials and should not be used to diagnose, treat, or prevent any condition. Anyone with diabetes, prediabetes, liver disease, or other health concerns should consult a qualified healthcare professional before making changes to their diet, supplements, or medications.
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.