While the food we eat can influence health, new research suggests we should also turn our attention to the packaging it comes in, after revealing how exposure to a chemical commonly used in plastics for food packaging and other products may lead to weight gain.

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Researchers found exposure to DEHP – a chemical often found in food packaging – led to weight gain in female mice.

Martin von Bergen, head of the Department of Molecular Systems Biology at the Helmholtz Centre for Environmental Research (UFZ) in Germany, and colleagues found that the chemical di-(2-ethylhexyl)-phthalate (DEHP) led to a hormone imbalance in female mice that triggered weight gain, even when exposed to the chemical in low concentrations.

The team – including researchers from the University of Leipzig and the University Hospital Leipzig, also in Germany – recently published their findings in the journal PLOS One.

DEHP is a type of phthalate, or plasticizer, that is added to plastics to make them more soft, flexible or sturdy. As well as in food packaging, phthalates are present in some children’s toys, medical tubing, vinyl flooring, adhesives, and even in some personal care products – such as nail polish and shampoo.

However, ingesting foods that have come into contact with phthalate-containing packaging is the most common way we are exposed to the chemicals, and numerous studies have associated phthalate exposure with health problems.

Last year, for example, a study reported by Medical News Today associated the phthalates di-isononyl phthalate (DINP) and di-isodecyl phthalate (DIDP) with increased risk for hypertension, while an earlier study associated phthalate exposure in expectant mothers to increased risk of preterm birth.

Previous research has also suggested phthalate exposure may lead to weight gain, but von Bergen and colleagues say little is known about the mechanisms underlying this association – something they set out to uncover with this latest study.

The team reached their findings by exposing mice to DEHP. They added various concentrations of the chemical to the animals’ drinking water for 10 weeks and assessed how it impacted weight, comparing the effect with mice that were not exposed to DEHP.

Both groups of mice consumed standard chow over the 10-week study period.

The researchers found that female mice exposed to DEHP gained significantly more weight than non-exposed female mice. Weight gain was even identified among mice exposed to low concentrations of the chemical, though no such association was found in exposed male mice.

On assessing the metabolic products in the blood of the female mice, the team identified an increase in expression of estrogen receptors and reduced expression of Pparg receptors in adipose tissue, which they say could contribute to changes in metabolism that cause weight gain.

Commenting on what their findings show, von Bergen says:

It is evident that phthalates seriously interfere with the hormone balance. They give rise to significant changes, e.g. weight gain, even in low concentrations.”

He notes that some metabolic changes mediated by activity in adipose tissue can also influence functions in other organs. “However,” von Bergen adds, “there is no conclusive clarification of how the various effects of phthalates on metabolism influence each other and ultimately lead to weight gain.”

The team plans to continue investigating how phthalates affect metabolism, as well as assess how the chemicals influence the development of diseases in early childhood.

In September 2014, a study reported by MNT suggested prenatal exposure to phthalates may raise the risk of childhood asthma.