Environmental footprint of a soybean-supplemented low-fat vegan diet in postmenopausal women: a secondary analysis of a randomised clinical trial

Background Dietary patterns that limit or avoid animal products contribute fewer greenhouse gases and require less energy than diets containing more animal products. However, quantifications of these outcomes on a vegan diet in real-life conditions still need to be explored. Methods In a randomised controlled trial, a low-fat vegan diet supplemented with soybeans led to a significant reduction in hot flashes in postmenopausal women. In this secondary analysis of that study, we hypothesised that the intervention diet would have a reduced environmental impact, greenhouse gas emissions (GHGEs) and cumulative energy demand (CED). 3-day diet records were analysed at baseline and at the end of the 12-week study, and we linked dietary intakes to environmental footprints. Results Compared with no change in the omnivorous control group, we found that the vegan group had a decrease in GHGEs (p <0.001) of 35% (−662.7 g CO 2- eq/person-day) and a decrease in CED (p =0.002) of 34% (−4956 kJ/person-day). These reductions in environmental impact were primarily due to reduced consumption of meat and dairy products. Conclusion Adoption of a soybean-supplemented low-fat vegan diet significantly reduced cumulative energy demand and GHGEs, important drivers of climate change. Trial registration number NCT04587154 .