A new UC Davis study shows that having fermented food like sauerkraut could be good for gut health. (Credit: Hector Amezcua / UC Davis)
In a nutshell
- Fermented cabbage, but not raw cabbage or brine, protected intestinal cells from inflammation-related damage in lab tests, suggesting unique gut health benefits created during fermentation.
- Researchers identified specific compounds like D-phenyl-lactate (D-PLA), indole-3-lactate (ILA), and GABA that increased during fermentation and contributed to gut barrier protection.
- The full mix of metabolites in fermented cabbage was more effective than individual compounds alone, pointing to the potential of sauerkraut and similar fermented foods as natural gut-supporting options.
DAVIS, Calif. — Those jars of sauerkraut in your refrigerator might be doing more than adding tangy flavor to your sandwiches and hot dogs. A new study from the University of California, Davis reveals that fermented cabbage contains compounds that could help protect your intestinal lining from inflammation damage.
The study, published in the journal Applied and Environmental Microbiology, reveals that fermented cabbage, but not raw cabbage, protected intestinal cells against damage caused by inflammatory proteins. This finding suggests that the fermenting process transforms ordinary cabbage into a potential gut health powerhouse.
For anyone suffering from digestive issues or concerned about gut health, including fermented foods like sauerkraut in your diet might offer genuine benefits beyond their distinctive flavor profile.
Sauerkraut’s Gut-Protective Powers
The study focused on what happens when intestinal cells are exposed to inflammatory proteins that typically damage the gut lining, a condition associated with various digestive disorders, including inflammatory bowel disease. When the researchers applied fermented cabbage extract to these cells, they found it prevented the damage that would normally occur.
What makes this discovery particularly intriguing is that the protective effect wasn’t observed when using raw cabbage or just the brine solution. Something specific happens during the fermentation process that creates or enhances compounds that benefit gut health.
The fermentation of cabbage relies on lactic acid bacteria naturally present in the vegetable. These bacteria transform sugars into lactic acid and other compounds, creating the distinctive flavor of sauerkraut while also generating bioactive metabolites that appear to offer health benefits.
The research team examined both laboratory-fermented cabbage and commercial sauerkraut. They even tested batches with and without the addition of a specific strain of beneficial bacteria (Lactiplantibacillus plantarum) to see if it enhanced the protective effects.
Beneficial Compounds Created During Fermentation
Through extensive metabolomic analysis – essentially mapping all the compounds present in both raw and fermented cabbage – the researchers identified 149 metabolites using gas chromatography and 333 metabolites using liquid chromatography. This comprehensive analysis showed significant differences between what raw and fermented cabbage are made up of.
“It doesn’t matter, in a way, if we make sauerkraut at home or we buy it from the store; both kinds of sauerkraut seemed to protect gut function,” says study author Maria Marco from UC Davis, in a statement.
Fermentation consistently decreased carbohydrate content while increasing levels of lactic acid, lipids, amino acid derivatives, and phenolic compounds. Three compounds in particular caught the researchers’ attention: D-phenyl-lactate (D-PLA), indole-3-lactate (ILA), and gamma-aminobutyric acid (GABA). All three were substantially higher in fermented cabbage compared to raw cabbage.
When scientists tested the individual compounds from fermented cabbage on their own, they found the compounds offered some protection to the gut lining, but not as much as the full fermented cabbage extract. This suggests it’s the combination of compounds working together that delivers the strongest benefit.
How Beneficial Bacteria Enhance Fermented Foods
According to the researchers, these findings align with what’s already known about the gut microbiome. Fermenting cabbage creates a mix of helpful compounds, like D-PLA and ILA, that are also naturally made by good bacteria in your gut, where they’ve been shown to help maintain intestinal barrier function.
This might also apply to other fermented vegetables. Fermented foods have been dietary staples across numerous cultures for thousands of years, valued not only for preservation but also for their unique flavors and traditional associations with health benefits.
What This Means for Your Diet and Gut Health
“Along with eating more fiber and fresh fruits and vegetables, even if we have just a regular serving of sauerkraut, maybe putting these things more into our diet, we’ll find that can help us in the long run against inflammation, for example, and make our digestive tract more resilient when we have a disturbance,” says Marco.
Modern science is now catching up, with mounting evidence that these foods may indeed deliver tangible health advantages. While additional research, particularly human trials, will be needed to fully understand the extent of these benefits, this study provides compelling evidence that the age-old practice of fermenting vegetables creates more than just interesting flavors.
“A little bit of sauerkraut could go a long way,” adds Marco. “We should be thinking about including these fermented foods in our regular diets and not just as a side on our hot dogs.”
Those tangy fermented cabbage strands might be doing more than adding zip to your Reuben sandwich; they could be helping to maintain the crucial barrier that keeps your digestive system functioning properly.
Paper Summary
Methodology
Researchers created laboratory-scale fermentations (LSF) of cabbage with and without added Lactiplantibacillus plantarum NCIMB8826R (LP8826R) bacteria and sampled them after 7 and 14 days. They also obtained commercial sauerkraut samples. They tested these samples on Caco-2 cells, which are laboratory cell lines that mimic human intestinal epithelial cells. The cells were exposed to inflammatory cytokines (interferon gamma and tumor necrosis factor-alpha) that typically damage intestinal barriers. Researchers measured trans-epithelial electrical resistance (TER) and permeability to fluorescent dextran to assess barrier function. They also conducted extensive metabolomic analyses using gas and liquid chromatography to identify compounds in both raw and fermented cabbage, then tested individual compounds (lactate, D-PLA, and ILA) to see if they could replicate the protective effects.
Results
Fermented cabbage homogenates, but not raw cabbage or brine alone, protected Caco-2 cell monolayers against cytokine-induced damage. This protection occurred despite increased IL-8 production (an inflammatory marker). Metabolomic analyses identified 149 metabolites by gas chromatography and 333 by liquid chromatography, revealing significant differences between raw and fermented cabbage. Fermentation consistently increased lactic acid, lipids, amino acid derivatives (including D-PLA, ILA, and GABA), and phenolic compounds while decreasing carbohydrates. When tested individually, lactate, D-PLA, and ILA only partially protected against cytokine-induced damage, suggesting the full mixture of compounds in fermented cabbage provides better protection than individual components. Cabbage fermented with added LP8826R bacteria produced metabolite profiles more similar to commercial sauerkraut than those without the bacteria.
Limitations
The study used a cell culture model (Caco-2 cells) rather than human subjects, so the findings may not directly translate to human health outcomes. The researchers note that additional studies should explore other fermented cabbage products to determine if barrier protection is consistent across different products. They also suggest that future research should investigate the effects of different homogenization methods on the soluble fermented cabbage metabolome and consider how cabbage is metabolized in the human digestive tract. Human studies would ultimately be needed to determine recommended intakes for physiologically relevant benefits.
Funding and Disclosures
The research was funded by a Specialty Crop Block Grant from the California Department of Food and Agriculture (CDFA) and the Jastro and Shields Graduate Research Award from the University of California, Davis. The lead author, Maria Marco, is also supported by the University of California Agricultural Experiment Station and the multi-state hatch grant W5122. The authors declared no conflicts of interest.
Publication Information
The study titled “The fermented cabbage metabolome and its protection against cytokine-induced intestinal barrier disruption of Caco-2 monolayers” was authored by Lei Wei and Maria L. Marco from the Department of Food Science and Technology at the University of California Davis. It was published in the journal Applied and Environmental Microbiology in April 2025 (Volume 0, Issue 0, Article 02234-24).
