A pair of new studies have found a potential link between teen insulin resistance and obesity and phthalates and bisphenol A, two chemicals commonly found in certain types of food packaging. However, the researchers aren’t sure whether the increased prevalence of obesity and insulin resistance is directly due to the presence of these chemicals, or whether other factors are responsible. The researchers plan to conduct additional studies to gain a better understanding of the link.
BPA in particular has increasingly become a topic of contention. The chemical is widely used in plastics and can be found in the packaging of many foods and drinks. It is also present in infant bottles, medical devices, canned food and water bottles. While many of these things can be avoided, BPA might also be found in certain water supply pipes.
Phthalates Linked to Insulin Resistance, Type 2 Diabetes
In a study conducted by New York University, researchers measured phthalate levels in the urine of 766 individuals between the ages of 12 and 19. The specific phthalate for which the researchers tested was DEHP, which is commonly contained in processed foods. Adolescents with the highest phthalate levels in their blood were also more likely to show signs of insulin resistance, a precursor of Type 2 diabetes.
Phthalates are also found in skin and beauty products such as makeup and shampoos, but the researchers found no link between these types of chemicals and insulin resistance. In conducting their study, the researchers were careful to account for additional risk factors for insulin resistance including body mass index and daily caloric intake.
The study was headed up by Dr. Leonardo Tresande, who previously worked with the same researchers to identify a link between insulin resistance and phthalate intake in adults. Dr. Tresande said that phthalates act similar to hormones in that they influence how insulin is secreted in response to sugar, often in ways that are unhealthy.
At the same time, the researchers admitted that the link could possibly be explained by other causes. Teens predisposed to higher insulin resistance could simply have higher levels of DEHP secretion, or they could prefer foods that happen to contain higher levels of phthalates. As mentioned previously, more research will be needed in order to confirm the link.
BPA Linked to Obesity
An additional recent study, this one conducted by the University of Michigan, found a link between bisphenol A, or BPA, and obesity. The children in the study, of whom there were over 10,000 between the ages of 6 and 18, who had the highest levels of BPA in their urine were twice as likely to be obese as those with the lowest levels of BPA.
However, lead researcher Dr. Joyce Lee said that other factors could be responsible for the results. Children who are already obese may simply be eating more food sold in BPA-containing packaging. It’s also possible that since BPA is more readily contained in fat tissue than lean body tissue, people with higher body fat percentages may store more of the chemical and excrete more of it in their urine.
Questions from Other Experts
Thomas Jefferson University pediatrics professor Dr. Robert Brent published a commentary attached to the new studies in which he described how testing BPA and phthalate content in urine may not be the best way of determining a person’s chemical-exposure levels. This is because the human body metabolizes BPA and phthalates very quickly and eliminate it as waste through the urinary tract. However, the danger occurs when these chemicals are left behind in the bloodstream.
In previous studies on people known to have high exposure to BPA, high amounts of BPA were found in their urine as well. However, levels of BPA in their blood were still found to be extremely low at virtually undetectable levels.
Further, Dr. Brent said that any BPA left over in the bloodstream is incapable of attaching to hormone receptors because of the way it’s already been metabolized. Still, Dr. Brent didn’t deny the fact that BPA exposure has been linked with many diseases, including cancer, birth defects, diabetes, autism, obesity and more.
The Bottom Line
Two new studies indicate that phthalates and BPA, chemicals found in certain types of food packaging, may be linked to obesity and insulin resistance. The full text of both studies can be found online here and here in the medical journal Pediatrics.
