Research Links A Common Food Packaging Plastic To Liver Damage

At this point, hearing that microplastics are everywhere probably isn't surprising. They've been detected in our food, drinking water, air, and even throughout the human body. What we're much less clear on is what happens once they're there.

And not all plastics have been studied equally. Polyethylene, the plastic commonly used in food packaging, plastic wrap, storage containers, and some beverage cup linings, is actually the most widely produced plastic in the world. Yet compared with other microplastics, researchers know relatively little about how it affects our health.

For the new study, published in Science Advances, researchers exposed mice to polyethylene microplastics and examined what happened inside their livers. Some mice ate a standard diet, while others ate a diet designed to promote metabolic dysfunction-associated steatohepatitis, or MASH, a more advanced form of fatty liver disease.

This allowed researchers to look at two questions: whether polyethylene could affect an otherwise healthy liver and whether exposure might make existing metabolic stress worse.

Polyethylene exposure was associated with signs of liver dysfunction in mice eating both diets. But when the microplastics were combined with the MASH-promoting diet, liver damage became more pronounced.

That combination is particularly interesting because our exposures don't happen in isolation. Diet, exercise, environmental chemicals, sleep, and countless other factors are all interacting with our biology at the same time. This study suggests microplastics could be one more piece of that larger metabolic picture.

Researchers also identified changes in pathways involved in how the liver processes fat, responds to stress, and repairs itself. One protein that stood out was PPAR-alpha, which plays an important role in fatty acid metabolism and inflammation. They also identified changes involving ANXA2, a gene involved in the liver's response to damage and tissue repair.

Because this study was conducted in animals, we can't conclude that eating food from polyethylene packaging causes fatty liver disease in humans. We also don't yet know how the doses used experimentally compare with the complicated, long-term exposures people experience in real life.

Still, the study adds to a growing body of research raising questions about how microplastics may affect metabolic health, and it gives researchers specific biological pathways to investigate in humans.

In the meantime, the answer is trying to eliminate every piece of plastic from your life. That's nearly impossible, and we still have a lot to learn about which exposures matter most. Instead, there are a few fairly easy places to cut back.

Avoid heating food in plastic when you can, especially in the microwave, since heat can increase the release of particles and chemicals from some plastics. Store leftovers in glass or stainless steel more often, and transfer hot takeout food out of plastic containers once you get home. You can also use glass or reusable bottles for water, replace worn or heavily scratched plastic food containers, and choose less-packaged foods when it's convenient.

We still don't know exactly what lifelong microplastic exposure means for human liver health, and this study shouldn't be interpreted as proof that polyethylene causes fatty liver disease in people.