Researchers tested whether a specific type of helpful bacteria called Lactobacillus reuteri could reduce inflammation in mice with ulcerative colitis, a disease that causes painful swelling and ulcers in the colon. The mice that received this bacteria showed significant improvements: they lost less weight, had shorter colons that returned to normal size, and showed less inflammation and damage. The bacteria also helped strengthen the intestinal lining and increased production of beneficial compounds. These results suggest this bacteria might become a useful treatment for people with ulcerative colitis, though more research in humans is needed.

The Quick Take

  • What they studied: Whether giving mice a specific probiotic bacteria (Lactobacillus reuteri) could reduce symptoms and damage from ulcerative colitis, a disease that causes colon inflammation and ulcers.
  • Who participated: Male laboratory mice (Balb/C strain) divided into three groups: healthy mice, mice with induced colitis, and mice with colitis that received the bacteria treatment.
  • Key finding: Mice receiving Lactobacillus reuteri showed significant improvements in all measured areas: they experienced less weight loss, reduced inflammation markers, better intestinal lining integrity, and increased production of beneficial short-chain fatty acids compared to untreated colitis mice.
  • What it means for you: This research suggests that Lactobacillus reuteri probiotics may help reduce inflammation and repair intestinal damage in ulcerative colitis patients. However, this is early-stage research in mice, and human studies are needed before recommending it as a treatment. Talk to your doctor before starting any probiotic supplements.

The Research Details

Scientists used laboratory mice to model ulcerative colitis by giving them a chemical called dextran sodium sulfate (DSS) in their drinking water for one week. This chemical damages the colon lining and causes inflammation similar to what happens in human ulcerative colitis. The mice were divided into three groups: a healthy control group, a group with induced colitis that received no treatment, and a group with induced colitis that received daily doses of Lactobacillus reuteri bacteria.

The researchers measured multiple indicators of disease and healing. They tracked weight changes, examined the physical appearance and length of the colon, measured inflammation markers in the blood and tissue, looked at the structure of the intestinal lining under a microscope, and measured the production of beneficial compounds called short-chain fatty acids. This comprehensive approach allowed them to understand how the bacteria affected different aspects of the disease.

Using a mouse model allows researchers to carefully control all variables and measure effects that would be difficult or impossible to measure in humans. The DSS-induced colitis model is well-established and produces disease features very similar to human ulcerative colitis. By measuring multiple outcomes—from visible symptoms to microscopic tissue changes to molecular markers—the researchers could understand exactly how the bacteria works to reduce inflammation and repair damage.

This study was published in PLoS ONE, a peer-reviewed scientific journal, which means other experts reviewed the work before publication. The researchers used standardized methods for inducing colitis and measuring outcomes, making the results reproducible. However, this is a mouse study, so results may not directly translate to humans. The study appears to be well-designed with appropriate control groups and multiple measurement methods, which strengthens confidence in the findings.

What the Results Show

Mice treated with Lactobacillus reuteri showed dramatic improvements compared to untreated colitis mice. They experienced significantly less weight loss during the disease, which is important because weight loss is a major symptom of ulcerative colitis. The colon length, which typically shrinks during colitis, was restored to nearly normal length in treated mice.

Inflammation markers dropped substantially in treated mice. Specifically, harmful inflammatory proteins (TNF-α, IL-1β, and IL-6) decreased significantly, while a protective anti-inflammatory protein (IL-10) increased. Under the microscope, tissue samples from treated mice showed much less inflammation, fewer damaged crypts (small pouches in the intestinal lining), and fewer ulcers compared to untreated colitis mice.

The bacteria also strengthened the intestinal barrier—the protective lining that prevents harmful substances from entering the bloodstream. Key proteins that hold this barrier together (ZO-1 and Claudin-1) were significantly increased in treated mice. Additionally, the bacteria increased production of short-chain fatty acids, which are beneficial compounds that feed healthy gut bacteria and reduce inflammation.

The study measured disease activity index (DAI), a scoring system that combines multiple symptoms. Treated mice had significantly lower DAI scores, indicating overall disease improvement. Myeloperoxidase (MPO) levels, which indicate the presence of immune cells causing inflammation, were substantially reduced in treated mice. These secondary findings support the primary conclusion that the bacteria reduces inflammation through multiple mechanisms.

This research builds on previous studies showing that Lactobacillus reuteri has anti-inflammatory properties. The novelty here is demonstrating that this specific bacteria can effectively reduce colitis symptoms and repair intestinal damage in a well-established disease model. The findings align with growing evidence that certain probiotics can modulate the immune system and improve gut health, though this is one of the more comprehensive evaluations of L. reuteri’s effects in colitis.

This study was conducted in mice, not humans, so the results may not directly apply to people with ulcerative colitis. Mice have different immune systems and gut bacteria than humans. The study used only male mice, so results may differ in females. The researchers induced colitis artificially with a chemical, which may not perfectly replicate the complex causes of human ulcerative colitis. Additionally, the study doesn’t specify the exact number of mice used in each group or provide detailed statistical analysis information. Long-term effects of L. reuteri treatment were not evaluated. Finally, this is a single study, so results need confirmation by other research groups before drawing firm conclusions.

The Bottom Line

Based on this research, Lactobacillus reuteri shows promise as a potential treatment for ulcerative colitis, but it’s too early to recommend it as a standard treatment. The evidence is moderate-to-strong for the bacteria’s anti-inflammatory effects in the laboratory setting, but human clinical trials are needed. If you have ulcerative colitis, discuss with your gastroenterologist whether probiotic supplementation might be appropriate for your situation. Don’t replace prescribed medications with probiotics without medical guidance.

People with ulcerative colitis or inflammatory bowel disease should be aware of this research as a potential future treatment option. Researchers studying gut inflammation and probiotics should take note of these findings. People interested in preventive health and gut bacteria may find this interesting, though the research doesn’t yet support using this bacteria for prevention in healthy people. Healthcare providers treating inflammatory bowel disease should monitor for future human studies on this bacteria.

In this mouse study, improvements appeared within the one-week treatment period while colitis was being induced. In humans, if this bacteria proves effective, benefits would likely take weeks to months to appear, as the intestinal lining repairs itself gradually. Any human studies would need to track patients for several months to assess both short-term symptom relief and long-term disease management.

Want to Apply This Research?

  • If using probiotics under medical supervision, track daily probiotic intake (yes/no), gastrointestinal symptoms (bowel movement frequency, urgency, pain on a 1-10 scale), and energy levels. Record any changes in symptom severity weekly to identify patterns.
  • Users could set a daily reminder to take a probiotic supplement at the same time each day (if recommended by their doctor), log their digestive symptoms before and after starting supplementation, and note any dietary changes made alongside probiotic use to identify what combination works best for their individual situation.
  • Establish a baseline of current symptoms before starting any new supplement. Track symptoms consistently for at least 4-8 weeks to allow time for potential effects. Create a simple symptom diary noting bowel movements, pain levels, energy, and overall well-being. Share tracked data with your healthcare provider at regular appointments to assess whether the supplement is helping and whether any adjustments are needed.

This research was conducted in mice and has not yet been tested in humans with ulcerative colitis. The findings are promising but preliminary. Do not start, stop, or change any ulcerative colitis medications or treatments based on this research without consulting your healthcare provider. Probiotics are not regulated by the FDA in the same way as medications, and quality and effectiveness can vary between products. People with severe ulcerative colitis, weakened immune systems, or those taking immunosuppressive medications should consult their doctor before using any probiotic supplements. This information is for educational purposes only and should not replace professional medical advice.