Every morning, millions of Americans press a single button to get a hot cup of coffee. As much as they enjoy instant comfort, it may have hidden health costs.
Like many others kitchen goodsThe capsules and cups used inside these coffee machines often contain plastic materials. Research shows that these materials can release microplastics that then end up in coffee, and new research suggests that long-term exposure to microplastics in general can compromise health. In 2024, researchers showed that patients with microplastics in their arteries had a higher risk of heart attack, stroke and early death.
“We already have evidence that many plastics and associated microplastics contain hazardous chemicals that can cause harm,” says Justin Boucher, an environmental engineer and director of operations for the Food Packaging Forum, a nonprofit that tracks research into how materials affect food.
Scientists have found that coffee capsules and cups may contribute to this problem.
Cause for concern
Many coffee capsules and disposable cups contain plastic, which breaks down when brewing coffee. They can end up in your drink, creating a cocktail of caffeine and microscopic debris.
Microplastics are pieces of plastic. less than five millimeters. They have become ubiquitous thanks to our strong addiction on plastic and enter our body in several ways. One way is through plastic food packaging; their microplastic can migratealong with plastic related chemicalsinto food.
Because they are so small microplastics are absorbed and carried by blood to vital organs. Laboratory studies of human and animal cells show that they can cause inflammation, oxidative stressAnd immune disorders– problems that contribute to the development of various diseases.
What is currently missing is clear evidence that microplastics directly cause these diseases, says Mohamed Abdalla, professor of environmental chemistry at the University of Birmingham in the UK. “Our understanding of the toxicity of microplastics remains in its infancy,” adds Abdallah. But he thinks we know enough for people to worry.
Just like the inside of your body, it's important to understand the inner workings of your single-cup coffee machine. It heats the water to about 190°Falmost boiling, and passes it through the capsule under high pressure. When the brewed coffee is poured from the pod, the heat and pressure releases chemicals from the plastic and breaks down into tiny pieces, which then slide silently into the dark brown swirl.
Read more: What happens to the plastic in dishwasher containers?
This year Abdullah published research on coffee capsules of three different brands. When he examined the coffee made from the pods, he found significant levels of microplastics. He confirmed the source of these microplastics, tracing them back to the same type of plastic used to make each capsule.
Christopher Helt, a toxicologist and director of the GreenScreen Certified® program for the nonprofit Clean Production Action, notes that “there is a distinct possibility that chemical additives may be leaching into coffee.” But he also believes contamination can be limited because the capsules are exposed to high heat and pressure for a relatively short time – just a minute or so.
Abdalla says results may vary depending on the specific methods chosen to measure microplastics and associated chemicals. “Depending on what you look at, the numbers vary,” he explains. For example, studies could use different mesh sizes to filter out microplastics, Abdalla says.
2020 paper Researchers at the University of Connecticut found that chemicals from plastic capsules leach into coffee in small quantities, but they didn't look specifically at microplastics like Abdalla did.
More research is needed. “In general, there is a lack of very robust research on this topic,” says Lisa Zimmermann, a biologist and science liaison with the Food Packaging Forum. But she adds that the materials in the cups and capsules “are very complex and contain many different ingredients that are needed to withstand the high temperatures and pressures inside the machines.” With this complexity, combined with high temperature and pressure, “a lot more chemicals can end up in the coffee,” Boucher says.
US Food and Drug Administration (FDA) haven't installed it yet appropriate standards for assessing exposure to microplastics in food. “The federal government hasn't done anything specific about microplastics,” says Tracy Woodruff, a health policy professor at the University of California, San Francisco and a former senior US government scientist. The FDA did not respond to TIME's request for comment.
A strong alternative
Given the research into potential hazards, Boucher and Zimmerman see value in taking a cautious approach. One alternative in particular is safer and less expensive in the long run: capsules and cups. stainless steel.
Stainless steel safer warmer than plastic. “The complex chemistry required to preserve the physical properties of plastic is not needed to protect stainless steel,” says Boucher. Steel capsules are initially more expensive, but they can be washed and reused, unlike single-use plastic ones. Third-party companies design them to be compatible with popular machines like Keurig and Nespresso.
Some companies advertise capsules and cups made from bioplastics that are at least partially plant-based or intended to mimic plant-based versions and provide potential health and environmental benefits. But substitutes are still made from complex materials that include additives such as dyes; Chemicals can react in ways that companies don't plan or understand, Boucher said.
Read more: The Dirty Secret of Alternative Plastics
Biomaterials such as cornstarch used in some alternative cups have their benefits, but they can still be dangerous, Helt says. Some research suggests that bioplastics are as toxic as other plastics.
Meanwhile, Nespresso capsules are mainly made of aluminum. However, a Nespresso spokesperson confirmed via email that their capsules contain small amounts of non-aluminum materials, including plastic.
Keurig, which sells the popular K-Cups coffee pods, did not respond to TIME's requests for comment. The Plastics Industry Association, a trade association, had no comment.
Other sources of microplastics
Plastic capsules and cups aren't the only sources of microplastics in your morning drink. “There are so many different paths,” Abdallah says.
One of these is the machine itself, since its internal parts are usually made of plastic – both in single-cup brewers and drip coffee makers. In the same 2025 study, Abdallah found microplastics in machine-brewed coffee drinks, as well as in capsules and cups. He analyzed an eight-year-old car and newer cars about a year old. “The old machine released more microplastics than the two new versions,” says Abdallah.
When considering the age of your coffee maker, consider a PVC chaise lounge. “After it's been sitting in your backyard in the sun for months or years, it might just start to decompose,” Boucher says. High temperatures have a similar effect on your car.
Single cup machines often have external water reservoirs made of plastic. “This could also be a source of microplastics,” says Abdallah. The water itself may contain microplastics before it even passes through the machine. However, as Abdalla discovered, the coffee coming out the other end contains almost two-thirds more of these impurities.
There's also milk if you add it. “At the manufacturing stage, milk can pass through hundreds of feet of plastic tubing,” Boucher says, potentially leading to more microplastics.
Coffee may contain even more microplastics if drunk from disposable paper cups; some are covered in plastic. Whenever possible, choose glass, Abdalla says. Food Packaging Forum conducts research database about plastics contaminating food products, including paper cups.
These other sources of microplastics associated with long-term consumption of coffee capsules may increase health risks. Researchers believe people can reduce their risk by using stainless steel capsules. Woodruff went even further: she bought a stainless steel machine.
Build in these improvements gradually to limit plastic-related stress. Woodruff remembers his own efforts over time as a journey. “I didn’t turn it all off overnight,” she says. “People should just remember that you can't blame yourself and wider changes depend on government and industry action. Do what you can.”
