Researchers studied how dietary patterns relate to levels of per- and polyfluoroalkyl substances (PFAS) in the human body over time, and found that greater consumption of tea, processed meats, and food prepared outside the home (inferring that the food was in contact with packaging) to be associated with increased levels of the forever chemicals in the body.

The study was funded in part by the U.S. National Institutes of Health (NIH) and led by researchers at the Keck School of Medicine of the University of Southern California (USC). The researchers studied two groups of participants—123 young adults from the Southern California Children’s Health Study (CHS), who were primarily Hispanic, and 604 young adults from the National Health and Nutrition Examination Study (NHANES), a nationally representative sample.

The results also point to the importance of testing and monitoring various food and beverage products for contamination with PFAS. The researchers express concern that even foods that are metabolically quite healthy can be contaminated with PFAS, which are known for their human health harms.

Each participant answered a series of questions about their diet, including how frequently they consumed various foods (such as processed meats, dark green vegetables, and bread) and beverages (including sports drinks, tea, and milk). They also reported how often they ate food prepared at home, or at fast-food or non-fast-food restaurants, which researchers used to infer contact with food packaging.

Participants also gave blood samples, which were tested for levels of various PFAS. The CHS group was tested twice, once around age 20 and once around age 24; the NHANES group was tested once, around age 19.

In the CHS group, participants who reported higher tea consumption during the first visit had higher levels of PFAS at the follow-up visit. A single additional serving of tea was linked to 24.8 percent higher levels of perfluoro- hexanesulphonic acid (PFHxS), 16.17 percent higher perfluoroheptanesulfonic acid (PFHpS) and 12.6 percent higher perfluorononanoic acid (PFNA). Those who reported more pork intake on their initial visit also had higher levels of PFAS at follow-up, with one additional serving of pork linked to with 13.4 percent higher perfluorooctanoic acid (PFOA) levels.

Eating food prepared at home had the opposite effect: for every 200-gram increase in home-prepared food, perfluorooctanesulfonic acid (PFOS) levels were 0.9 percent lower at baseline and 1.6 percent lower at follow-up. These findings are important because they not only reveal the presence of traditional PFAS, such as PFOA and PFOS, but also more recently developed PFAS, including PFHxS and PFHpS.

Those results were confirmed in the NHANES group. Participants who consumed more tea, hot dogs, and processed meats had higher PFAS levels, while eating more home-prepared food was linked to lower PFAS levels.

Observing that links between PFAS levels and food products change over time suggests that dietary changes could impact PFAS levels in the body, according to the researchers. The findings also suggest that public monitoring of certain products, such as beverages, could help identify and eliminate sources of contamination.

The research team is now conducting research on the extent of PFAS contamination in popular tea brands, as well as a follow-up study on diet and PFAS levels in a multi-ethnic group of participants.