A bacterium commonly found in the human gut produces a compound that lowered cholesterol and shrank artery plaque in mice, according to a study published Oct. 7 in Nature. The microbe, Bacteroides uniformis, makes pentadecanoic acid, a fatty acid that blocks a liver enzyme involved in cholesterol production, the same enzyme targeted by statin drugs, according to Nature's news coverage.

In genetically engineered mice prone to clogged arteries and fed a high-fat diet, giving live B. uniformis lowered total and LDL cholesterol and reduced plaque in the main arteries. The findings have not been tested as a treatment in people.

The study adds to growing evidence that microbes living inside the body help regulate human health, much as soil and ocean microbes regulate ecosystems. It also points to a possible new approach for people whose cholesterol stays high despite medication.

Inside the Cholesterol Pathway

When the liver's cholesterol-making enzyme is blocked, the liver builds more LDL receptors, which pull excess cholesterol out of the blood. Statins work through that same enzyme, which is why the bacterial compound has drawn comparisons to the widely prescribed drugs.

In the mice, the bacterium also reduced the number of inflammatory immune cells infiltrating artery walls. Inflammation plays a central role in how plaque builds up and breaks loose.

The mouse plaque results need careful reading — the reported size of the effect is inconsistent. Nature's coverage describes the reduction as about half in its opening and as about one-third in the main arteries in its detailed account, without explaining the difference. Readers should treat the size of the effect as uncertain until it is confirmed against the paper's own figures.

Clues From Human Volunteers

The researchers also analyzed blood and stool samples from more than 200 donors. People with abnormally high blood fats had lower levels of pentadecanoic acid than healthy volunteers, and people with heart disease carried fewer bacterial genes for making the compound.

An initial stool screen helped point the team toward the microbe: B. uniformis was often less abundant in people with heart disease than in healthy individuals. Those human findings are associations. They do not show that the bacterium lowers cholesterol in people or that lacking it causes heart disease.

The study was led in part by researchers including microbiologist Wenjing Zhao of Sun Yat-sen University in Shenzhen, China, according to Nature. Full author affiliations, funding sources and competing interests are listed in the paper.

Independent Experts Urge Caution

Ben Chen, a cardiovascular specialist at the Monash Victorian Heart Institute in Melbourne, Australia, who was not involved in the study, said the work provides "evidence for a potentially causal biological mechanism" linking gut microbes to blood vessel health, according to Nature.

That is a measured endorsement — not a call to change treatment. Mouse models of atherosclerosis often respond to treatments that later fail in humans, and the dose, form and safety of any bacterial or compound-based therapy would need clinical trials.

The motivation is real, though. Statins alone do not lower cholesterol enough in nearly half of people with advanced heart disease, and some people cannot tolerate high doses, according to Nature's coverage. That leaves room for complementary approaches. If the findings hold, people who cannot reach their cholesterol goals on statins, or who cannot tolerate them, are the group most likely to benefit eventually. But any such therapy would first need to prove it works and is safe in clinical trials, a process that typically takes years.

Animal results often look stronger than what later appears in people. Nature World News recently reported that semaglutide extended lifespan in older female mice, another promising animal finding that still requires confirmation in humans before it changes medical practice.

An Evidence Check for Readers

Study type: a laboratory and animal study combined with observational human samples, published in a peer-reviewed journal. What it found: a gut microbe's compound lowered cholesterol and plaque in mice, and people with heart problems tended to have less of the compound and fewer genes to make it. What it did not prove: that the bacterium or compound helps people. Details such as how long the mice were treated and the dose they received were not described in the news coverage and should be checked in the full paper before anyone draws conclusions about how strong the effect is.

The findings do not change medical advice. People taking statins or other cholesterol medicines should not stop or change them based on this research, and there is no evidence yet that probiotic products or supplements containing this compound reduce heart risk. Anyone with questions about cholesterol should talk with a doctor.

Pentadecanoic acid also occurs naturally in some foods, including dairy fat, but the study did not test diet, and eating more of those foods is not supported by this research as a way to lower cholesterol.

The microbiome angle has a wider meaning. Gut bacteria are shaped by diet, antibiotics and environment, and researchers are learning that losing particular microbes can alter body chemistry in ways that matter for disease, similar to how losing key species can change an ecosystem.

The next steps are confirming the findings in more animal models and, eventually, testing whether boosting the bacterium or its compound is safe and effective in people. The bottom line is that a common gut microbe appears to make its own statin-like compound, a promising lead that remains a long way from the pharmacy shelf.

What Readers Want to Know

What bacterium did the study examine?

The study examined Bacteroides uniformis, a bacterium commonly found in the human gut.

How does it lower cholesterol?

It produces pentadecanoic acid, which blocks a liver enzyme involved in cholesterol production, the same enzyme targeted by statins.

Did it work in people?

It has not been tested as a treatment in people. Human samples showed only associations between the compound and blood fat levels or heart disease.

How much did plaque shrink in mice?

Nature's coverage describes a reduction of about one-third in the main arteries in one passage and about half in another, so the exact size should be confirmed in the paper.

Should I stop taking statins or buy probiotics?

No. The research does not change medical advice. Talk to a doctor before changing any cholesterol treatment.

What comes next?

Researchers need more animal studies and, eventually, clinical trials to test safety and effectiveness in people.