---

Related Topics

---

A study published in Proceedings of the National Academy of Sciences reveals how plant proteins and dietary fiber may work together to support a healthier gut microbiome. Researchers from Princeton University and collaborating institutions discovered that certain plant proteins are not completely broken down during digestion. Instead, some of these proteins reach the large intestine, where gut bacteria use them as nutrients. The researchers called these digestion-resistant proteins “protein imitating fiber,” or Prif, because they behave somewhat like dietary fiber. Their findings suggest that these proteins may help explain why plant-based diets are associated with beneficial changes in gut bacteria and the chemicals they produce.

To investigate this process, the scientists conducted experiments using mice fed diets containing different protein sources, including rice, soy, peas, eggs, beef, and dairy proteins. They also examined how different types of fiber affected bacterial activity. Using chemical tracing techniques, the researchers followed how nutrients were processed by gut bacteria and identified the substances produced during digestion. They found that certain plant proteins, especially rice protein, allowed more undigested protein to reach the large intestine. This increased the production of two substances called hippuric acid and 3-phenylpropionate, which have been associated with beneficial health outcomes.

The study also revealed an important role for soluble fiber. When gut bacteria have limited access to dietary nutrients, some can break down proteins released by the body, including proteins found in the protective mucus lining of the intestine. This process can contribute to the production of substances such as phenol sulfate and p-cresol sulfate, which are considered potentially harmful because they can accumulate in people with impaired kidney function. The researchers discovered that soluble fibers, including pectin and inulin, reduced the production of these substances by limiting bacterial breakdown of the body’s own proteins. Meanwhile, digestion-resistant plant proteins increased the availability of nutrients that bacteria could use to produce health-associated compounds.

These findings suggest that plant proteins and dietary fiber have different but complementary effects on gut microbial activity. Plant proteins that resist digestion can encourage the production of certain health-associated substances, while soluble fiber can help reduce the formation of potentially harmful bacterial products. However, the researchers also observed that some plant protein diets increased certain unwanted metabolites, showing that the effects depend on the overall diet. Most experiments were conducted in mice, and the study did not establish that these chemical changes directly improve human health. Further studies involving people are needed to determine whether similar effects lead to measurable health benefits. Nevertheless, the research provides new insight into how different components of plant-based foods can influence the gut microbiome.

References

AbuSalim, J. E., MacArthur, M. M., Gupta, M., Roichman, A., Hunter, C. J., Keber, F. C., Chatterjee, S., Moussavi, M., Barouei, J., Wühr, M., Sulakhe, D., Lehmann, C. J., Donia, M. S., & Rabinowitz, J. D. (2026). Digestion-resistant proteins support the healthy metabolite profiles associated with plant-based diets. Proceedings of the National Academy of Sciences, 123(32), e2605226123. https://doi.org/10.1073/pnas.2605226123

AI Disclosure Statement:
The Chromoscience uses AI-assisted tools to support the preparation and editing of science articles. Content is reviewed by the editor for clarity and consistency with the cited research before publication. Readers are encouraged to consult the original scientific publications for complete findings, methods, and limitations.