Researchers discovered that a specific type of probiotic bacteria called Bacillus subtilis natto might help prevent heart disease by changing how the immune system works. In a study with mice, this bacteria reduced the buildup of plaque in arteries without lowering cholesterol levels. Instead, it worked by encouraging the immune system to create more protective cells that fight inflammation. This finding is exciting because it suggests a new way to prevent heart disease that doesn’t rely on traditional cholesterol-lowering approaches. The results could eventually lead to new treatments for people at risk of heart attacks and strokes.

The Quick Take

  • What they studied: Whether a special probiotic bacteria could slow down or prevent the buildup of plaque in arteries (atherosclerosis) by changing how the immune system works
  • Who participated: Laboratory mice that were genetically modified to develop heart disease similar to humans. The study lasted 16 weeks with daily treatment.
  • Key finding: Mice that received the bacteria had significantly less plaque buildup in their arteries compared to mice that didn’t receive it, even though cholesterol levels didn’t change much. The bacteria appeared to work by boosting protective immune cells.
  • What it means for you: This research suggests that probiotics might help prevent heart disease through a completely different mechanism than cholesterol-lowering drugs. However, this is early-stage research in mice, so human studies are needed before this could become a treatment option.

The Research Details

Scientists used laboratory mice that were engineered to develop atherosclerosis (clogged arteries) similar to what happens in humans. Half the mice received daily doses of the Bacillus subtilis natto bacteria for 16 weeks, while the other half received a placebo (inactive substance). The researchers then examined the mice’s arteries and blood to see what changed.

To understand how the bacteria worked, the scientists used advanced technology called flow cytometry to identify and count different types of immune cells in the blood. They looked at 18 different immune cell types to create a detailed picture of how the immune system changed over time.

This approach allowed the researchers to track not just whether the bacteria helped, but exactly how it helped by showing which immune cells changed and when those changes happened.

Understanding the exact mechanism—how something works—is crucial for developing new treatments. Rather than just showing that the bacteria helped, this study revealed that it works through the immune system, not by lowering cholesterol. This opens up a completely new approach to preventing heart disease that could complement existing treatments.

This study used a well-established animal model of heart disease and employed sophisticated technology to measure immune changes. The researchers tracked changes over time rather than just looking at one point, which provides stronger evidence. However, because this is animal research, results may not directly translate to humans. The study was published in a peer-reviewed scientific journal, meaning other experts reviewed it before publication.

What the Results Show

The most important finding was that mice receiving the bacteria had significantly smaller areas of plaque buildup in their arteries compared to control mice. This reduction was substantial and measurable. Interestingly, this benefit occurred without major changes in blood cholesterol levels, suggesting the bacteria works through a different pathway than cholesterol-lowering drugs.

The immune system changes were complex and happened in stages. Early on, the bacteria triggered an expansion of certain trained immune cells—think of these as immune cells that have been ‘activated’ and are ready to fight. Over time, the immune system shifted toward having more regulatory T cells, which are special immune cells that calm down inflammation and prevent the immune system from overreacting.

The bacteria also increased the number of naive CD8+ T cells (young immune cells that haven’t encountered threats yet) while reducing memory cells that promote inflammation. This shift toward a calmer, more balanced immune response appears to be what protected the arteries from plaque buildup.

The researchers found that the bacteria did not significantly change other types of immune cells like monocytes, neutrophils, or eosinophils. This was actually important information because it showed the bacteria’s effect was very targeted—it specifically affected T cells rather than broadly suppressing the entire immune system. Mice also experienced a mild decrease in body weight, though this was not the main focus of the study.

Previous research had shown that Bacillus subtilis natto has anti-inflammatory properties, but the exact mechanism wasn’t clear. This study fills that gap by demonstrating that the bacteria works primarily through the adaptive immune system (the part that learns and remembers threats) rather than the innate immune system (the part that responds immediately). This is different from many other probiotics that work through broader immune suppression. The finding that cholesterol levels didn’t need to change for the protective effect to occur challenges the traditional view that heart disease prevention requires lowering cholesterol.

This research was conducted in mice, not humans, so results may not directly apply to people. The study didn’t test different doses or durations to find the optimal treatment. The researchers also didn’t compare this bacteria to existing heart disease treatments, so it’s unclear how it would perform against standard medications. Additionally, the study used a specific strain of bacteria (NTU-18) and specific mice, so results might differ with other strains or in different populations. Finally, the mechanism of how the bacteria causes these immune changes wasn’t fully explained—the researchers showed what happened but not all the details of why it happened.

The Bottom Line

Based on this research, we cannot yet recommend this bacteria as a treatment for humans. This is preliminary animal research that shows promise. Before anyone should consider using this bacteria, human clinical trials would be needed to confirm safety and effectiveness. If you have heart disease risk factors, continue following your doctor’s advice about diet, exercise, and medications. This research may eventually lead to new treatment options, but that’s likely years away.

This research is most relevant to people interested in heart disease prevention, researchers studying probiotics and immunity, and pharmaceutical companies developing new treatments. People with family histories of heart disease or those at high risk should follow this research but shouldn’t change their current treatment plans based on this single animal study. People with compromised immune systems should be cautious about new probiotics until human safety data is available.

In this mouse study, changes in immune cells began within the first few weeks and continued throughout the 16-week treatment period. If this eventually becomes a human treatment, benefits would likely take weeks to months to develop, similar to how other immune-based therapies work. However, this is speculative until human trials are conducted.

Want to Apply This Research?

  • Track daily probiotic intake (if recommended by a doctor) alongside cardiovascular health markers like resting heart rate, blood pressure readings, and any chest discomfort or unusual symptoms. Record these weekly to monitor patterns over time.
  • If this research eventually leads to a recommended probiotic supplement, users could set daily reminders to take it at the same time each day, similar to taking a vitamin. They could also track complementary heart-healthy behaviors like exercise minutes, servings of vegetables, and stress levels to create a comprehensive heart health picture.
  • Establish a baseline of current cardiovascular health metrics (blood pressure, cholesterol levels, weight) and track these quarterly through doctor visits. Use the app to log daily supplement use and correlate it with symptom changes or improvements in cardiovascular markers over 3-6 month periods. Share this data with healthcare providers to inform treatment decisions.

This research was conducted in laboratory mice and has not been tested in humans. The findings are preliminary and should not be used to guide personal health decisions. Do not start, stop, or change any heart disease treatments or medications without consulting your doctor. If you are considering probiotic supplements, discuss them with your healthcare provider first, especially if you have a weakened immune system, are taking medications, or have existing health conditions. This article is for educational purposes only and is not a substitute for professional medical advice.