Unfortunately, the old saying 'you are what you eat' seems to apply to chemicals. 

In a new study, researchers examined how diet affects the levels of 'forever chemicals' in our bodies. They found that people who ate out more often and consumed more ultra-processed foods and tea had higher blood levels of PFAS (per and poly-fluoroalkyl substances).

PFAS are found in household products such as non-stick cookware, food packaging, and water and stain repellents. PFAS have a very stable chemical structure, making them robust and difficult to dissolve, so they are often called 'forever chemicals'. They have been linked to many adverse health effects, including an increased risk of liver cancer, high cholesterol, and obesity.

Several studies have shown that diet accounts for a large proportion of PFAS exposure. Whether through contact with food packaging or non-stick cookware, human exposure to PFAS is ubiquitous, which explains why PFAS has been detected in more than 98% of the U.S. population aged 12 years and older. 

In the new study, researchers focused on understanding how dietary trends and food choices influence blood levels of 'forever chemicals' by looking at a group of adults between the ages of 19 and 24. They focused on a younger cohort because that's when people tend to move out of their parent's homes and develop their adult eating habits.

The team focused on two multiethnic groups of young adults, one representative of the U.S. population and one primarily Hispanic, for a total of 700 people. Each participant answered a series of questions about their diet during two visits to the lab, including how often they consumed foods such as processed meats, dark green vegetables, bread, and beverages such as sports drinks, tea, and milk. They also reported how often they ate food prepared at home, at a fast-food restaurant, or a non-fast-food restaurant, which the researchers used to estimate exposure to food packaging, which usually contains PFAS. 

Participants also provided blood samples that were tested for levels of various 'forever chemicals' at the two visits, allowing scientists to look at the evolution of PFAS over time.

The team's analysis showed that the more tea, pork, sports drinks, chips, and bottled water people consumed, the higher the levels of PFAS in their blood. The strongest associations were found with tea and pork consumption. Previous studies based on the same U.S. population assessed in this study had already shown that higher meat consumption was associated with higher levels of PFAS. One hypothesis behind this finding could be that animals are exposed to these chemicals in their drinking water and feed.

However, one finding that wasn't as predictable was the link between 'forever chemicals' and tea. "That was pretty surprising, and that's definitely the one we're looking at the most because it's a newer finding,"  Hailey Hampson, a doctoral student at the University of Southern California and the study's lead author, said in an interview with Tech Times. Hampson explained that this study only found an association, not causation, and reinforces that more research is needed to truly understand whether tea causes an increase in PFAS levels. "We want to be very careful," she added.

Jesse Goodrich, from the same university and who also worked on the research, is equally cautious about the findings and reinforces tea's good side. "Unsweetened tea has been linked with a lot of health benefits. Tea has been linked to protection against inflammation and oxidative stress," he added.

As for the next steps, Hampson and Goodrich want to work towards understanding what is causing this link between PFAS and tea consumption and whether different teas might lead to different results. "The plan is to look at different types of tea: loose leaf, tea bags, premade teas like iced tea, and even teas that are brewed in plastic cups," Hampson explains. "That will hopefully help us actually get to the root of what is driving this association." 

Dimitri Abrahamsson, a researcher from New York University who wasn't involved in this study, says the results are interesting but agrees that more research is needed. When discussing the accuracy of results like these, he raises concerns about studies based on food questionnaires. "One thing that can be tricky when studying chemical associations with dietary habits using questionnaire data is that people often do not remember and accurately report what they eat or how often they eat it," he adds. He argues that there is a consistent trend of underreporting when it comes to dietary intake, which can increase uncertainties. "Perhaps combining questionnaire data with metabolomic profiling or other biomarkers specific to certain foods could potentially reduce some of these uncertainties," he said.

Bárbara Pinho is a freelance writer.