Associations between ultra-processed food consumption and phthalate exposures in pregnant women

By Pooja Toshniwal PahariaFeb 12 2024Reviewed by Danielle Ellis, B.Sc.

In a recent study published in Environment International, researchers explored the relationship between consuming ultra-processed foods and urinary phthalate concentrations during pregnancy. They also investigated whether the ultra-processed category of food items mediates socioeconomic discrepancies in exposure to phthalate compounds.

Background

The global use of processed foods has contributed to an increase in chronic diseases such as metabolic syndrome and inflammatory bowel disease. Processed diets may influence health in ways other than nutritional quality, and phthalates, chemicals added to processed foods, or pollution during processing and packaging may contribute to human disease. Understanding sources of phthalate exposure, especially during pregnancy, is critical for public health, particularly in low-income populations.

About the study

The researchers of the present study evaluated the association between the consumption of ultra-processed foods and phthalate exposure among expecting pregnant women.

The team analyzed data from 1,031 expecting women of the Conditions Affecting Neurocognitive Development and Learning in Early Childhood (CANDLE) Study cohort. They enrolled 1,503 women aged 16 to 40 years with healthy singleton pregnancies during their second trimester (between weeks 15 and 29 of gestation) between 2006 and 2011.

The team administered the study participants Block-type Food Frequency Questionnaires (FFQs) to assess their habitual intake of 114 foods and beverages in the previous three months. They also obtained urine samples from the participants to measure urinary phthalate metabolite concentrations in trimester two of pregnancy by liquid chromatography-tandem mass spectrometry.

The researchers excluded individuals with a previous history of chronic disease requiring medication (e.g., diabetes, hypertension, and sickle cell disease), known pregnancy complications (e.g., oligohydramnios and placenta previa), or plans to deliver at a nonparticipating hospital. They adjusted for missing data on maternal diets and urinary phthalate concentrations using Multivariable Imputation by Chained Equations (MICE).

The researchers performed linear regressions to model the relationships between consuming ultra-processed foods and phthalate exposure and different food items of the ultra-processed type. They also conducted exploratory factor assessments of diet patterns. Covariates included maternal age, ethnicity, race, educational attainment, number of household members, household income, neighborhood deprivation index, pre-pregnancy body mass index (BMI), alcohol intake, tobacco use, and regular caloric intake.

The team used complementary NOVA classification to classify foods and performed exploratory factor assessments to account for the potential for bias in manual food categorization and the potential for limited interpretability of data-driven food categorization. They also performed causal mediation assessments to investigate whether consuming ultra-processed foods mediates associations between socioeconomic differences and phthalate exposure.

Results

The mean participant age was 27 years; 61% were African American or black, and 34% were white. Most women (91%) did not consume alcohol or tobacco during their pregnancy and consumed 2,410 calories (mean) each day in the early pregnancy period. Urinary concentrations of phthalic acid and 16 phthalate metabolites were beyond the threshold in more than 70% of samples.

Most mothers more frequently consume minimally processed foods than ultra-processed ones, with ultra-processed food items representing 9.8% to 59% (mean, 39%) of participant diets, whereas minimally processed foods represented 31% to 81% (mean, 50%). Mothers from the topmost ultra-processed food intake quartile showed an increased likelihood of being younger, less educated, having lower household income, higher neighborhood deprivation, and higher regular calorie intakes.

A ten percent higher dietary percentage of consuming ultra-processed food items was related to 13% higher molar di(2-ethylhexyl) phthalates (ΣDEHP) concentrations. A ten percent higher intake of foods from the minimally processed category showed associations with lower ΣDEHP values (11%). Minimally- and ultra-processed food intake was not related to non-DEHP metabolite concentrations. One standard deviation increase in the intake of cheeseburgers or hamburgers, French fries, cake, and soda increased ΣDEHP values by 11%, 9.2%, 6.0%, and 7.4%, respectively.

Exploratory factor assessment findings supported positive associations between processed food intake and ΣDEHP values and uncovered healthy diets related to lower ΣDEHP values in urine for phthalates such as mono(2-ethyl-5-carboxypentyl) (MECPP), mono(2-ethyl-5-hydroxyhexyl) (MEHHP), mono-isononyl (MINP), and mono(2-carboxymethylhexyl) (MCMHP). Lower educational attainments and household incomes were related to 1.4% and 1.9% higher ΣDEHP values, respectively, mediated through higher intake of ultra-processed foods.

Conclusion

Overall, the study findings showed that consuming ultra-processed food items can increase phthalate exposure, emphasizing the importance of dietary phthalate reduction strategies. Consuming fast food, such as cheeseburgers and French fries, was associated with higher urinary ΣDEHP levels. Pregnant women consuming vegetables, fruits, yogurt, fish, and nuts had lower ΣDEHP and MINP levels. Diets high in minimally processed foods showed reduced urine phthalate concentrations. Lower household income and maternal education were associated with higher urine ΣDEHP levels. Policy changes to limit phthalate exposure are crucial.