Adolescents with a higher urinary phthalate concentration were associated with increased insulin resistance and diabetes…
Di-2-ethylhexylphthalate (DEHP) is a type of phthalate chemical found in the environment that is commonly found in foods that are processed or in food packaging items. Previous studies have shown that when an adult is exposed to this chemical, the same chemical that is used to soften plastic, they are more likely to exhibit insulin resistance and be obese. However, since these studies focused on adults, Trasande et al. wanted to see if these phthalates had a similar effect on adolescents.
For the study, the authors used cross-sectional data that came from the 2003-2008 nationally representative health and nutrition survey. Those included in the analysis (n=766) were fasting 12-19 year olds. Researchers examined phthalate urinary concentrations as well as the "continuous and categorical measures of homeostatic model assessment of insulin resistance" among the participants. "Demographic and behavioral factors, diet, continuous age, BMI category, and urinary creatinine" were adjusted for.
The authors found that urinary levels of DEHP were in fact tied to an adolescent’s likelihood of having insulin resistance. Of the adolescents who had the lowest levels of DEHP in their urine, about 15% were insulin resistant; 22% of those who had the highest level of DEHP in their urine exhibited insulin resistance.
While the results show some association between phthalate exposure and insulin resistance, they do not prove that eating packaged foods leads to insulin resistance. It is possible that adolescents who displayed the insulin resistance happened to eat foods with higher phthalate levels. According to the authors, another possibility is that "insulin resistant children may excrete more DEHP."
Regarding the increased insulin resistance seen among teenagers today, Dr. Leonardo Trasande said, "clearly unhealthy diet and lack of physical activity are the drivers of this epidemic … but increasingly, environmental chemicals are being identified as possible contributors."