Gut Bacteria Fatty Acid C15:0 Halved Artery Plaque in Mice

This is animal research. The authors used a mouse model of atherosclerosis, the build-up of fatty plaque in artery walls. The work also included human comparisons, but these were observational: they looked at differences between patients and healthy people, not at a treatment given to people.

The starting point was a known pattern. Bacteroides, a dominant genus in the human gut, is depleted in patients with atherosclerosis. Until now it was unclear whether that loss was a cause of the disease or just a sign of it. In mice, the researchers report, giving one species, Bacteroides uniformis, eased atherosclerosis. They link this to higher levels of the LDL receptor in the liver. That receptor pulls LDL cholesterol, the harmful kind, out of the blood.

The team then screened for the bacterium's active ingredient. They identified pentadecanoic acid, also called PA or C15:0. It is a saturated fatty acid with an odd number of carbon atoms. According to the study, PA supplementation reduced plaque burden by around 50% and significantly improved plasma lipid profiles in the mice.

The proposed mechanism is familiar. The authors report that PA directly inhibits HMG-CoA reductase, the liver enzyme that statin drugs target. That slows the liver's own cholesterol production and helps clear LDL cholesterol from the blood. The authors describe this as gut–liver crosstalk, meaning chemical signals from gut microbes that change how the liver handles cholesterol.

Two further findings add context. Across 100 gut bacterial strains, PA production occurred in multiple genera within the Bacteroidota group, not just one species. And PA was markedly depleted in patients with dyslipidaemia, meaning unhealthy blood fat levels. That last finding is an association. It does not show that low PA causes high cholesterol, or that raising PA would fix it.

The study's own wording is cautious about benefit. It says the work underscores PA's "therapeutic potential" and that changing the microbial–metabolic axis has "atheroprotective potential". It does not claim a treatment.

The coverage went further in places. Lifespan.io, which reported on the paper, called the molecule a "natural statin". It also said atorvastatin, a widely used statin, worked noticeably better than C15:0 at the same dose in the mice. It added that C15:0 appears to be a weaker inhibitor of the enzyme. These comparisons come from Lifespan.io's account. Lifespan.io also noted, about the 12week B. uniformis experiment, that results were compared with vehicle-fed controls at the end rather than with baseline. That shows slowed plaque growth, not necessarily reversal. We do not know whether the same applies to the C15:0 experiment.

That is why this matters for personal choices. C15:0 can be bought as a supplement, but nothing here shows that taking it helps people's arteries. Mouse doses, gut absorption and long-term safety in humans are all untested in this work. Lifespan.io put it plainly: "it is not clear that C15:0...is superior to statins in any way." Statins have large human trials behind them.

The more useful takeaway is the direction of the science. Gut bacteria may help set cholesterol levels through the molecules they make. If that holds up, it could eventually lead to new ways to support heart health. Lifespan.io quotes study coauthor Wenjing Zhao of Sun Yat-sen University as saying the findings underline new ways the microbiome might be harnessed to protect the heart. Lifespan.io itself adds that more studies, especially in humans, are needed.

What to watch next

Human trials that test whether raising C15:0, or the bacteria that make it, lowers LDL cholesterol safely, and how that compares with statins.

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