BMJ study finds plant-based diet cuts food-related emissions by 35% in randomized clinical trial

A randomized clinical trial published in BMJ Nutrition, Prevention & Health has found that replacing meat and dairy with a plant-based diet reduced diet-related greenhouse gas emissions by 35%, while also delivering measurable health benefits.

A randomized clinical trial found that switching to a low-fat vegan diet reduced diet-related greenhouse gas emissions by 35% over 12 weeks.
The study reported a 34% reduction in total energy demand associated with food production, processing and distribution.
Participants also experienced health improvements, including a 92% reduction in severe hot flashes and average weight loss of around 8 lbs.

The study analyzed dietary records from postmenopausal women who adopted a low-fat vegan diet, including half a cup of soybeans daily, over a 12-week period. Researchers linked participants’ food intake to environmental impact databases to estimate greenhouse gas emissions and cumulative energy demand associated with their diets.

Results showed that greenhouse gas emissions decreased by 35% in the vegan group, equivalent to a reduction of 662.7 g CO2-equivalent per person per day, while no change was observed in the control group. The reduction was largely attributed to the removal of meat and dairy products.

For an individual, the emissions savings were estimated to be comparable to eliminating approximately 600 miles of driving per year.

Hana Kahleova, director of clinical research at the Physicians Committee for Responsible Medicine and lead author of the study, said dietary change offered a direct way to reduce environmental impact.

“If you’re looking for a powerful way to shrink your carbon footprint, start with what’s on your plate,” said Kahleova. “Making this swap can help you reduce your greenhouse gas emissions as much as eliminating 600 miles of driving.”

The study also examined cumulative energy demand, a measure that accounts for the total energy required across the food lifecycle, including production, processing, packaging, transport, storage and waste. This metric decreased by 34% in the vegan group, representing a reduction of 4,956 kJ per person per day, with no comparable change in the control group.

Researchers reported that the reduction in energy demand was equivalent to the electricity required to power an average US household for approximately two hours.

Alongside environmental outcomes, the dietary intervention produced notable health effects. Participants in the vegan group experienced a 92% reduction in severe hot flashes and lost an average of around 8 pounds during the study period.

Kahleova said the findings demonstrated that environmental and health benefits could be achieved simultaneously through dietary changes.

“This research shows that replacing meat and dairy with plant-based foods can dramatically cut emissions while improving health at the same time,” she said.

The findings build on earlier research from the Physicians Committee, including a study published in JAMA Network Open that also reported reductions in greenhouse gas emissions and energy demand associated with plant-based diets.

Food production remains a significant contributor to global greenhouse gas emissions, with animal-based products typically associated with higher emissions intensity compared with plant-based alternatives. Researchers noted that dietary choices represent one of the more immediate levers available to individuals seeking to reduce their environmental footprint.

“Dietary choices are one of the most immediate actions individuals can take to reduce climate pollution,” Kahleova said. “Even modest changes, when adopted widely, could have a meaningful impact on climate change.”

The study adds to a growing body of evidence examining the environmental impact of dietary patterns, particularly as interest increases in strategies to reduce emissions across the global food system.