Taking Action to Thrive - A Healthy Lifestyle Intervention Pilot Study

Emerging evidence from in vitro and animal models suggests that exposure to endocrine disrupting chemicals (EDC), or industrial chemicals that alter hormonal action, may contribute to the development of obesity. Phthalates, a class of industrial chemicals commonly found in personal care products and food packaging, warrant study since they are widely detected in the general US population, including reproductive aged-women, and exposures during adulthood are associated with an increased risk of obesity. However, the majority of the evidence supporting this hypothesis to date has come from cross-sectional rather than prospective, longitudinal data. Thus, a causal relationship between EDC exposure and the development of obesity has not been conclusively established.

Currently, 60.3% (95% CI: 54.2-66.0) of younger adult Americans (aged 20 - 39) are thought to be overweight or obese (BMI ≥25), which increases the risk of chronic diseases such as diabetes, cardiovascular disease and cancer. While excess calorie consumption and lack of physical activity are primary contributors to overweight and obesity, factors other than diet and physical activity may also contribute to alterations in energy balance over time. The general public is becoming increasingly concerned about the potential health risks associated with EDC exposures, including effects on body composition.

The THRIVE Study is designed to evaluate the effect of many different EDCs on body composition changes. The study will focus initially on exposures to the phthalate class of EDCs, but data will be collected in a way that will allow investigators to evaluate the effect of many different EDCs on body composition changes.

Phthalates are a class of high-production-volume industrial chemicals that are ubiquitously used in commerce. Most phthalates, such as DEHP, are used as plasticizers to impart flexibility in polyvinyl chloride (PVC) materials such as food packaging, flooring, and medical devices. In recent years, other phthalates, including diisononyl phthalate (DiNP), have been replacing DEHP in these applications due, in part, to legislation limiting the use of DEHP in certain applications such as children's toys. Phthalates can leach, migrate, or off-gas from products over time and enter the human body through the air we breathe, the food we eat, and the personal care products that we use on our bodies. Consequently, human exposure to phthalates is widespread.

Phthalates enter foods through contact with plastics (e.g. tubing, conveyor belts or plastic gloves made with PVC plastics) or recycled paper/cardboard food containers. Phthalates are more likely to leach into liquids and non-polar solvents such as fats and oils, and thus are most commonly found in foods high in animal fats such as dairy products and meat. Low-molecular weight phthalates, such as DEP, di-n-butyl phthalate (DnBP) and DiBP, are commonly found in fragranced personal care products such as perfumes, deodorants, soaps, shampoos, and other hair products (e.g. hair sprays, gels, mousses). They can also be found in time release medications and supplements. Intervention studies suggest that addressing sources of exposure can lower human exposure to phthalates. In a study of 20 individuals, a 3-day dietary intervention of "fresh foods" (no canned food or foods wrapped in plastic) resulted in an average reduction in DEHP metabolites of 53-56%. Similarly, a study of 100 Latina girls found that a 3-day intervention with phthalate free personal care products resulted in a 27.4% reduction in DEP metabolite (mono-ethyl phthalate) levels.

If phthalate exposures are ultimately found to be associated with body composition changes in young adults, it could be possible to decrease the risk of these body composition changes by modifying food selection, preparation and storage techniques, and changing use of personal care products in addition to traditional diet and physical activity interventions. This, in turn, could have significant impacts on obesity and chronic disease risk in the US.

While a few studies have indicated that dietary modification and changes in personal care products use can individually lower urinary phthalate levels, this study will be the first to combine both a dietary and personal care product intervention. In a study of 20 individuals, a 3-day dietary intervention of "fresh foods" (no canned food or foods wrapped in plastic) resulted in an average reduction in DEHP metabolites of 53-56%. Similarly, a study of 100 Latina girls found that a 3-day intervention with phthalate free personal care products resulted in a 27.4% reduction in DEP metabolite (mono-ethyl phthalate) levels. The hypothesis of this study is that an intervention that addresses both dietary and personal care product phthalate exposures can result in an even greater decrease in urinary phthalate metabolites.