A healthy pregnancy diet may do more than support nutrient needs. It may also be linked to lower exposure to some chemicals found in food packaging, processing and cooking, according to a new study.
The observational study, published in the American Journal of Clinical Nutrition, included nearly 1,500 pregnant participants in the NIH-supported Environmental influences on Child Health Outcomes Cohort. Researchers found that diets more closely aligned with the U.S. Dietary Guidelines for Americans were associated with lower exposure to some environmental chemicals, including certain chemicals linked to food packaging. But the same eating patterns were also associated with higher exposure to some pesticides, likely because they included more fruits and vegetables. The findings do not mean pregnant people should avoid produce or that diet alone can control chemical exposure.
Diet can be one source of environmental chemical exposure. Chemicals may enter foods through farming, processing, packaging, storage or cooking. Pregnancy is a period of particular interest because some environmental exposures have been linked in previous research to health risks for mothers and children.
In the new study, researchers measured more than 100 chemicals in urine samples and compared those results with diet quality, based on how closely participants followed federal dietary guidance. A diet higher in fruits, vegetables, whole grains and lean proteins and lower in added sugar was linked with lower levels of some commonly encountered chemicals.
One example involved a phthalate that can leach into food from plastic packaging. Participants with higher-quality diets had levels of that chemical that were about 13% lower.
“What we discovered is that following the U.S. Dietary Guidelines may have two benefits—helping meet pregnancy nutrient needs and offering a way to reduce exposure to many common industrial chemicals,” said Dr. Diana Pacyga of the University of North Carolina Gillings School of Global Public Health.
But the results were not uniformly reassuring. Participants whose diets more closely followed the guidelines also had higher levels of certain chemicals, including some pesticides. The researchers noted that eating more fruits and vegetables and less added sugar was linked with higher levels of some pesticide biomarkers.
That finding can sound unsettling, especially during pregnancy, but it should not be read as a reason to cut back on fruits and vegetables. Produce remains an important part of a healthy pregnancy diet. Instead, the study highlights a difficult reality: Foods that support health can still be part of a food system where environmental exposures occur.
“Fresh fruits and vegetables are important for a healthy pregnancy diet, but they can also be a source of pesticides,” Pacyga said. “Buying organic, when possible, and washing or peeling produce may help reduce exposure while still eating these healthy foods.”
That advice may be useful, but it also has limits. Organic foods can cost more and may not be available to everyone. Washing produce is a practical step, but it does not remove every possible exposure. The study’s broader message is not that individuals can solve chemical exposure through perfect shopping choices. It is that nutrition guidance and environmental health guidance may need to work together more clearly.
The study also cannot prove that following dietary guidelines directly caused lower or higher chemical exposure. Because it was observational, it can show associations between diet quality and measured chemical biomarkers, not cause and effect. It also measured exposure markers, not whether these dietary patterns changed pregnancy or child health outcomes through chemical exposure.
Still, the findings point to a more nuanced way to talk about healthy eating during pregnancy. A diet built around fruits, vegetables, whole grains, lean proteins and less added sugar remains important. At the same time, food choices happen within larger systems of farming, packaging, processing and access.
“A modest revision of the dietary guidelines to include advice on reducing chemical exposures could help protect pregnant women’s health without changing the food recommendations we already know support good nutrition,” said Dr. Jessie Buckley of the University of North Carolina Gillings School of Global Public Health.
The research was supported by the Environmental influences on Child Health Outcomes Program through the Office of the Director at the National Institutes of Health, along with related NIH-supported centers, cores and cohort grants. One author also received support from the National Institute of Environmental Health Sciences and the National Institute of Diabetes and Digestive and Kidney Diseases. NIH participated in the overall design and implementation of the ECHO Program as a cooperative agreement, but the sponsor did not have access to the central database, did not conduct the scientific publication analyses and did not review or approve the manuscript before journal submission.