A low-plastic diet showed up in people’s urine inside a single week

Plastic-associated chemicals are so common in modern life that avoiding them entirely is nearly impossible, but a new Australian trial suggests a short, deliberate change in diet and kitchenware can measurably lower some of them in the body. Researchers put volunteers through a seven-day intervention that limited contact between food and plastic at every step, from farm to plate, then tested urine for chemical byproducts linked to plastic packaging and containers. Three chemicals dropped substantially in the group that changed both their food sourcing and their cookware, though the researchers are careful to note that what those reductions mean for long-term health is still an open question.

A seven-day trial layered on top of a larger observational study

The research, known as the PERTH Trial (Plastic Exposure Reduction Transforms Health), began with an observational cohort of 211 participants in Australia, followed by a randomized controlled trial involving 60 of those participants over seven days. It was led by clinical immunologist Michaela Lucas at the University of Western Australia, with Amelia Harray as co-first author, and the results are published in Nature Medicine. The observational phase found that exposure to plastic-associated chemicals was effectively universal: every one of the 211 participants excreted at least six different plastic-chemical metabolites on any given day, with highly processed, plastic-packaged and canned foods standing out as consistent contributors.

Four study arms separated food, kitchenware and personal-care products

For the seven-day intervention, the 60 participants were randomly assigned to a control group or one of four arms: eating low-plastic food; eating low-plastic food while also using plastic-free cooking equipment and utensils; switching only personal-care products such as shampoo to low-plastic versions; or combining all three changes at once. To keep the diet realistic, dietitians worked with more than 100 farmers and food producers to rework handling and packaging so participants could still eat pasta, salads, meat, butter, chocolate, fruit and snacks, keeping overall energy intake unchanged. Changing personal-care products alone had the smallest effect on urinary chemical levels, while the combined food-and-kitchenware group saw the largest shifts.

Three plastic-linked chemicals fell sharply in the combined group

In the group given both low-plastic food and plastic-free kitchenware, urinary levels of mono-n-butyl phthalate were 38 percent lower, monobenzyl phthalate levels were 54 percent lower, and bisphenol A levels were 60 percent lower than in the control group after just seven days. Phthalates are plasticizers that can migrate into food from packaging, plates or utensils, while bisphenols such as BPA and BPS migrate from the coating inside cans, food containers, cooking utensils, drink bottles, water pipes and cling film. Not every chemical the researchers tracked responded to the intervention, and the study notes that little is known about the health effects of BPS specifically, even though its use has already been restricted in some food-contact materials in the European Union.

Short chemical half-lives mean the drop reflects reduced exposure, not detox

Both phthalates and bisphenols have short half-lives in the body and are expected to clear rapidly once exposure stops, which is consistent with why a one-week intervention could shift urinary levels this quickly. “Our results showed strictly adhering to a diet of food which has not touched plastic, whether that is during production or packaging, can reduce plastic chemicals in our body in as little as a week,” Lucas said. She added that whether this kind of reduction “carries major health benefits is something that’s currently under further investigation,” a distinction the study itself does not resolve.

The trial doesn’t establish what these chemical levels mean for disease risk

Separate epidemiological research has linked phthalate and bisphenol exposure to associations with cardiovascular disease, metabolic syndrome and infertility, but those are observational links rather than proof that the chemicals cause the conditions, and this trial was not designed or powered to test disease outcomes at all. No safe threshold for these chemicals in the body has been established, and more than 16,000 chemicals are used across plastic manufacturing broadly, most of which were not measured in this study. The full results, published in Nature Medicine, describe the trial as a first demonstration that household-level changes can shift exposure quickly, while stopping short of claiming any measured health benefit.

Producers and packaging, not willpower alone, drove the biggest changes

Harray noted that the scale of the intervention required cooperation well beyond individual grocery choices, since food had to be produced, processed, packaged and delivered with minimal plastic contact by outside suppliers before it ever reached participants. That points to a practical limit on how easily any single household could replicate the results without similar support from producers. Since plastic production continues to rise and existing plastic in circulation is not disappearing, the researchers frame the findings as evidence that exposure can be reduced given the right supply chain, rather than as a simple individual lifestyle fix. The trial also only measured what happened during the seven days of the intervention, so it does not show whether chemical levels would stay lower with sustained effort or rebound quickly once participants returned to their normal shopping and cooking habits.

This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.