Vegetables including lettuce produce three times more greenhouse gas emissions than meats such as bacon, research into the food supply chain has found.
Fruits, vegetables, dairy products and seafood use greater resources and emit more greenhouse gas emissions per calorie through the supply chain process than pork, according to the study from Carnegie Mellon University.
The research studied energy use, "blue water footprint" (the total volume of water used) and greenhouse gas emissions associated with growing, processing and transporting food items, along with food sales and service and household storage in the US.
It found that the process of producing and transporting lettuces uses more resources per calorie than pork products because there are many more calories in bacon than lettuce. The shorter shelf life of products like lettuce also mean food waste is more likely, the research stated.
“Lots of common vegetables require more resources per calorie than you would think. Eggplant [aubergine], celery and cucumbers look particularly bad when compared to pork or chicken,” said Paul Fischbeck, professor of social and decisions sciences and engineering and public policy at Carnegie Mellon University.
Eating recommended foods such as fruits, vegetables, dairy and seafood results in energy use increasing by 38 per cent, water use going up by 10 per cent, and greenhouse gas emissions rising by six per cent.
This compares with a nine per cent reduction in energy and water use and greenhouse gas emission in the food supply chain when people eat fewer calories and lose weight.
“There’s a complex relationship between diet and the environment,” said the research’s co-author Michelle Tom. “What is good for us health-wise isn’t always what’s best for the environment.”