Plastic in your arteries: what those headlines really mean

You have probably seen the headline. Plastic found in human arteries. Plastic linked to heart attacks. It is the kind of story that makes you put down your coffee and stare at the wall for a minute.

The research is real, and worth paying attention to. But the headline version and the study version are not quite the same thing. Here is what the science actually says.

The study everyone is talking about

In 2024, a team of researchers published a paper in the New England Journal of Medicine that got the world's attention ^[1].

They looked at 257 people who had just had surgery to clean plaque out of the arteries in their neck. When they examined that plaque under powerful microscopes and specialized instruments, they found tiny plastic particles inside well over half of the samples. Most of the plastic was polyethylene, the same material used in grocery bags and food packaging.

Then they followed those patients for about three years. The people whose plaque contained plastic were more than four times as likely to have a heart attack, a stroke, or to die during that window than the people whose plaque did not

That is a striking result. It is also the point where the story gets more complicated.

What the study did not show

The word “linked” is doing a lot of work in those headlines. What the researchers found is what scientists call an association: two things showing up together. What they did not find is a cause.

The people with plastic in their arteries also tended to have more of everything else that damages blood vessels — more air pollution exposure, more smoking history, different diets, different jobs. A single snapshot study, no matter how well done, cannot fully separate the plastic signal from all of those other well-known risks. The editors of the same journal made exactly that point in an editorial published alongside the study ^[2].

A follow-up study in the European Heart Journal found plastic particles in the coronary blood of most patients showing up with the most serious kind of heart attack ^[3]. But those same patients had more air pollution exposure and more smoking history too. Air pollution and cigarette smoke are already known to damage arteries. Untangling which stressor is doing what is not something one study can do.

Two other studies round out the picture. One found higher blood plastic levels in patients with worse coronary disease ^[4]. Another found roughly six times more plastic in plaque than in the same patient’s blood ^[5]. That could mean plastic is pulled into already-damaged vessel walls, rather than causing the damage on the way through. The direction of the arrow is still unclear.

What the lab experiments suggest

The lab side of the science is where researchers try to figure out what plastic particles could be doing to blood vessels.

When human vessel-lining cells are exposed to plastic particles in a dish, they show signs of stress and damage ^[6]. When aging arteries are studied, plastic particles seem to speed up the wear-and-tear process at the cellular level ^[7]. In mice bred to develop heart disease quickly, high oral doses of microplastics made the plaque worse, at least in the males ^[8].

These are useful clues. They are also cells in a dish and mice on very high doses. None of them prove that the plastic amounts a normal person encounters cause disease in a normal human body.

Researchers who have pulled all this evidence together tend to land in the same place: the mechanisms by which plastic could harm blood vessels are plausible and worth studying, but the direct evidence in living humans is not there yet ^[9].

The right way to read all of this

“Plastic causes heart attacks” is more than the current science supports. A more honest sentence sounds like this:

Plastic particles have been found in human arteries. Their presence tracks with worse heart outcomes in observational studies. Lab work suggests reasonable ways they could contribute to vascular disease. Whether they actually drive the damage in real people at real exposure levels is still an open question.

That is less exciting than the headline. It is also closer to the truth. Overstating what we know is how public health messaging loses trust, and this is a topic where trust matters.

For readers who want a deeper look at how microplastics may interact with the systems that keep athletes performing (including the cardiovascular system), see our companion piece The performance question.

Notes on the science

A quick caveat for the curious. The main lab technique used to measure plastic inside human tissue is under active debate. A 2025 methods paper showed that certain body-fat chemicals can produce signals that look like polyethylene under this analysis, which may inflate some of the numbers being reported ^[10]. The core finding, that plastic particles are turning up in human blood vessels, still holds. But the exact concentrations should be read with a grain of salt for now.

Where Winnow fits in

If these headlines have left you unsettled, that is a reasonable response. The picture is not fully settled, but it is serious enough to be worth thinking about. And worth acting on where you reasonably can, through cleaner water, less plastic-packaged food, better indoor air, and cutting known cardiovascular risks like smoking.

Winnow is a probiotic consortium whose strains have been shown in laboratory testing to bind micro- and nanoplastics within the gut lumen, meaning at the point of first exposure, before absorption. It is not a cardiovascular therapy, and nothing above should be read as evidence that any supplement addresses particles already in your bloodstream or vessel walls. It is one small part of a broader response to a problem the science is still working to understand.