Low-Plastic Diet Trial Shows Significant Drop in Urine Chemical Levels Within a Week

Plastic is nearly impossible to avoid in 2026, but a new study suggests that simple changes in how we shop and cook could reduce the levels of certain plastic-associated chemicals in our bodies. A randomized controlled trial involving 60 participants in Australia found that a week-long intervention—emphasizing food with minimal plastic contact and plastic-free kitchenware—led to urine levels of three plastic-related chemicals dropping by up to 60% compared to a control group. The findings, published in Nature Medicine, offer a practical glimpse into how dietary choices might influence chemical exposure. Study Design and Key Findings Researchers from the University of Western Australia, led by clinical immunologist Michaela Lucas, designed a randomized trial to test whether eating foods processed, stored, and prepared without plastic could lower urinary levels of phthalates and bisphenols (including BPA and BPS). These chemicals are known to migrate into food from packaging, can linings, utensils, and even water pipes. Participants were divided into five groups: a control group and four intervention groups. The interventions included: Eating food produced and packaged with minimal plastic contact Eating low-plastic food while avoiding plastic cooking equipment and utensils Using only low-plastic personal care products, such as shampoo A combination of all three interventions After seven days, the group that adhered strictly to low-plastic food and used plastic-free kitchenware showed the most significant reductions. Specifically, mono-n-butyl phthalate levels dropped by 38%, monobenzyl phthalate by 54%, and bisphenol A by 60% compared to the control group. Why Personal Care Products Had Less Impact Interestingly, changes to personal care products had the least effect on urinary chemical levels. The researchers noted that the most impactful factor was the food itself—how it was produced, packaged, and prepared. How the Trial Was Conducted The research team went to considerable lengths to minimize plastic exposure for participants. Co-first author Amelia Harray explained that dietitians worked with over 100 farmers and food producers to modify handling processes and packaging, aiming to reduce plastic contact “from paddock to plate.” Participants had access to a wide range of foods they would normally eat—pasta, salads, meats, butter, chocolate, fruit, and snacks—ensuring that energy intake remained consistent. Before the trial, the team assessed plastic exposure in 211 participants and found widespread exposure to plastic-associated chemicals. All participants excreted at least six plastic chemical metabolites on any given day. Those with the lowest levels of these chemicals in their bodies tended to avoid fast food, highly processed foods, foods in plastic packaging, and microwaved meals in plastic containers. Implications and Uncertainties Both phthalates and bisphenols have short half-lives, meaning they are rapidly cleared from the body. However, the long-term health effects of these chemicals remain unclear. While numerous epidemiological studies have linked these pollutants to conditions like cardiovascular disease, metabolic syndrome, and infertility, the current study does not establish direct health outcomes. “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,” said Lucas. “If this also carries major health benefits is something that's currently under further investigation.” The researchers also highlighted that a “safe” level of plastic in the body is not yet known. If there is a health burden, it could accumulate over time unless exposure is reduced. Given that plastic production continues to rise, the findings offer a proactive approach for individuals. “This trial has delivered a message of hope that we can actively reduce plastic chemical levels in our bodies but is linked to significant changes in the way we produce and package our food,” Lucas added. The study provides evidence that dietary and kitchen habits can influence chemical exposure, but it also underscores the need for broader systemic changes in food production and packaging.