Randomised controlled trial of a low plastic diet and lifestyle intervention for adults with cardiometabolic risk factors: the Plastic Exposure Reduction Transforms Health (PERTH) trial - a protocol.

Abstract

Phthalates and bisphenols, chemicals commonly used in the production of plastic products, exhibit endocrine disrupting properties linked to obesity and systemic inflammation. Given the ubiquitous use of plastic chemicals, their adverse impact on human health is of great importance. In this protocol, we describe a randomised controlled trial aimed at testing whether minimising exposure to plastics and plastic-associated chemicals (PACs) in community-dwelling adults with cardiometabolic risk factors can reduce urinary excretion of PACs and improve cardiometabolic health. The study will recruit (n=60) community-dwelling adults (18-60 years) with cardiometabolic risk factors, characterised by a body mass index of ≥30 kg/m² and waist circumference of ≥88 cm in women and ≥102 cm in men. Participants will be randomised to a control (n=30) or an intervention group (n=30) receiving a 4-week diet and lifestyle modification designed to reduce plastic exposure, which includes the replacement of all food, kitchen utensils and equipment, personal care and cleaning products. The primary outcome is a reduction in urinary excretion of bisphenols after the 4-week intervention compared with the control arm. The secondary outcomes are the reduction in urinary excretion of low and high molecular weight phthalates. Finally, tertiary outcomes investigate improvements to cardiometabolic biomarkers, body composition, waist circumference and blood pressure. Participants will self-collect urine, stool and nasal lavage samples a day before beginning the intervention and at the end of each week. Fasting blood samples and health assessments will be collected during clinic visits: at baseline, mid-point and a day after the intervention period. Urinary PAC excretion and cardiometabolic health outcomes will be compared between the intervention and control groups. The PERTH Trial has ethics approval from the University of Western Australia Human Research Ethics Committee; 2021-ET001118. Results will be submitted for publication in peer-reviewed journals and presented at conferences. NCT06571994.