In a study published this month in Environment Systems and Decisions, researchers from Carnegie Mellon University measured the energy use, blue water footprint and greenhouse gas emissions required to make per calorie of each food group, including: fruits, seafood/fish, dairy, grains, meat, poultry, eggs, nuts, seeds, soy, sugars, fats and oils. They found that while meat produced the most greenhouse gas emissions, fruits, vegetables and fish/seafood required the most energy use, with fruits also creating the largest blue water footprint.
What it means
According to this study, replacing some of the meat in our diet with fruits and vegetables is worse for the environment.
The study only accounted for “blue water,” which is water taken from lakes, rivers and the ground. While blue water is important in drought-stricken California, farming in other parts of the world also relies on other types of water. In Canada, for example, the majority of water used for farming is “green” (rain water), with a minority of “grey” (recycled water). Furthermore, the environmental impact-per-calorie model resulted in high-calorie food groups such as sugars, fats and oils being the most efficient group, using the least amount of energy per calorie. But it would be unrealistic and unhealthy to suggest sugars, fats and oils replace fruits or vegetables. Researchers also categorized all fruits into a single group to calculate how much water, energy and emissions they produced per calorie. While fruits as a whole had the highest blue water footprint per calorie, not all fruits require equal amounts of water.