Burger King is improving its cows’ low-carb diet by adding 100 grams of lemongrass to reduce methane emissions (aka cow farts). The new diet plan will curtail methane emissions from cows by 33% per day, according to Burger King. Those emissions are one of the key contributors to climate change because the gas traps the sun’s heat and warms it. The Restaurant Brands International-owned company said the new lemongrass-fed beef will be used in Whoppers at some restaurants in Austin, Los Angeles, Miami, New York and Portland beginning Tuesday. Burger King said the new formula is “open source and fairly simple to implement,” and the company worked on it with with professors from the Autonomous University at the State of Mexico and University of California, Davis. Lemongrass is purported to help cows release less methane during the digestion process. According to the Environmental Protection Agency, around 50% to 65% of all methane emissions come from human activities, including factory farming. “If the whole industry, from farmers, meat suppliers, and other brands join us, we can increase scale and collectively help reduce methane emissions that affect climate change,” said Fernando Machado, global chief marketing officer for Restaurant Brands International, in a statement. Burger King has previously used its flagship menu item to promote sustainability and health initiatives. In February, an ad campaign was released featuring a moldy Whopper to highlight its efforts to eliminate artificial preservatives and other additives from the company’s menu. It’s aiming for all of their foods to be free of artificial ingredients by the end of this year.