Pregnant women should avoid fast food, says UW study. But it’s not why you think

Pregnant women may want to think twice before pulling into a fast food drive-thru for something to eat.

But the reason why is not likely what most people think.

A new report by UW Medicine researchers in Seattle did not target the fat, sugar or salt of fries, burgers or shakes.

The problem is the wrapping, packaging and the plastic gloves worn by food handlers that touch fast food and ultraprocessed food.

The plastics may contain and shed phthalates, a class of chemicals associated with plastics.

When ultraprocessed food, such as a muffin wrapped in plastic film, are consumed during pregnancy, phthalates can get into the mother’s bloodstream.

“When moms are exposed to this chemical, it can cross the placenta and go into fetal circulation,” said Dr. Sheela Sathyanarayana, a UW Medicine pediatrician and researcher at the Seattle Children’s Research Institute. She was the senior author of the study published in the journal Environmental International.

Previous studies have show that exposure to phthalates during pregnancy can increase the risk of low birth weight, preterm birth and child mental health disorders such as autism and ADHD.

The UW Medicine researchers also noted that as the intake of highly processed foods has increased globally, so have chronic diseases like metabolic syndrome and inflammatory bowel disease.

The UW Medicine study was the first in pregnant women to show that diets higher in ultraprocessed foods are link to greater phthalate exposures, researchers said in the study.

Researchers looked at the data for 1,031 pregnant women between 2006 and 2011. Their phthalate levels had been measured in urine samples collected during the second trimester of pregnancy.

Ultraprocessed food had composed 10% to 60% of their diets, for an average of about 39%.

Researches found that for every 10% higher the amount of ultraprocessed food they ate, they had a 13% increase in their urine of one of the most common types of phthalates.

The study also corroborated findings from other studies that healthy diets high in vegetables, fruits, yogurt, fish and nuts correlated with lower levels of some phthalates.

Ultraprocessed foods are made mostly from substances extracted from food such as oils, sugar and starch and may have been changed so much from processing and the addition of chemicals and preservatives that they are hard to recognized from their original form, researchers said.

They include foods like packaged cake mixes, packaged french fries, hamburger buns and soft drinks.

Phthalates may be introduced into fast foods from gloves worn by restaurant employees and the storage, preparation serving equipment or tools, according to UW Medicine.

Both frozen foods and fresh ingredients would be subject to those sources, said said lead author Brennan Baker, a postdoctoral researcher in Sathyanarayana’s lab.

Reducing phthalates

The findings have important implications for dietary choices during pregnancy, the researchers said.

Pregnant women should try to avoid ultraprocessed foods as much as they can and seek out fruits, vegetables and lean meat, Sathyanarayana said.

“Look for the lower number of ingredients and make sure you can understand the ingredients,” she said.

This applies even to “healthy foods” such as breakfast bars. See if it’s sweetened with dates or has a litany of fats and sugars in it, she said.

But due to the unpredictable means of contamination, it may not always be evident which foods should be avoided.

In addition, some women face financial hardships or live in “food deserts” where healthier food is not available of expensive.

The study was the first to identify ultraprocessed foods as a link between exposure to phthalates and social and economic issues facing pregnant women.

“We don’t blame the pregnant person here,” said Baker. “We need to call out manufacturers and legislators to offer replacements, and ones that may not be even more harmful.”

Legislation could regulate the composition of food wrapping or the gloves worn by food handlers.

“Policy reforms to reduce dietary phthalate exposures, especially from food packaging, are critically needed,” the report said.

Legislation could regulate the composition of food wrapping or the gloves worn by food handlers.