New research from the Physicians Committee for Responsible Medicine (PCRM) has found that replacing meat and dairy with plant‑based foods can cut diet‑related greenhouse gas emissions (GHGE) by 35%. The findings come from a randomised clinical trial of postmenopausal women who followed a low‑fat vegan diet, including half a cup of soybeans per day for 12 weeks.
The study used detailed food records from the trial and linked them to environmental impact databases to estimate GHGE and cumulative energy demand. They reported that greenhouse gas emissions dropped by 35%, while the energy required to produce the food eaten fell by 34%, mostly because meat and dairy were removed from their diets. For one person, the emissions reduction was framed as roughly equivalent to avoiding 600 miles of driving per year.
The health outcomes mirrored the environmental gains. Participants on the vegan diet experienced a 92% reduction in severe hot flashes and lost about 8 pounds on average during the 12‑week intervention. The study found that GHGE decreased by 662.7 g CO2‑eq per person per day in the vegan group, with no significant change in the control group, and the drop in emissions was associated with the reduction in severe hot flashes.
Cumulative energy demand, which includes the energy used to produce, process, package, transport, store, and dispose of food, dropped in the vegan group by 34%, or 4,956 kJ per person per day. This decline, again largely due to removing meat and dairy, was described as similar to the electricity needed to power an average US household for about two hours. Hana Kahleova, MD, PhD, director of clinical research at the Physicians Committee for Responsible Medicine and lead author of the study, said, “If you’re looking for a powerful way to shrink your carbon footprint, start with what’s on your plate…Making this swap can help you reduce your greenhouse gas emissions as much as eliminating 600 miles of driving…This research shows that replacing meat and dairy with plant‑based foods can dramatically cut emissions while improving health at the same time.”
