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Vegetarian and vegan options are sweeping the fast-food industry.

Taco Bell is testing a 100% vegetarian menu. Chipotle recently added new vegetarian and vegan items to its menu. And, on Monday, Burger King announced plans to roll out its vegan Impossible Whopper across the US by the end of 2019.

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Burger King is rolling out the vegan Impossible Whopper across America

Yet, as competitors roll out new menu items and announce deals with meat-substitute makers, McDonald’s has yet to take action. Currently, Baked Apple Pie is the only vegan item on McDonald’s American menu.

In a call with investors on Tuesday, McDonald’s CEO Steve Easterbrook explained why the chain hadn’t added a veggie burger to the menu.

Before adding a new plant-based menu item, Easterbrook said, McDonald’s needs to establish: “Is there an additional complexity? And if there is, is that complexity worth it?”

McDonald’s has recently been trying to focus on simplicity, slashing items from its late-night menu and killing its Signature Crafted line of upscale burgers. In the most recent quarter, the chain’s 4.5% growth in comparable sales was driven by new combinations of items that were already on the menu, such as adding bacon to burgers and cheesy fries.

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McDonald’s is killing its heavily hyped fancy burger lineup 2 years after launch

Despite concerns that new menu items could slow down workers and increase wait times, Easterbrook said that the chain is playing close attention to and internally discussing vegan and plant-based menu items.

“Maybe more to come,” Easterbrook said Tuesday, though he insisted there was not much at to say on the topic “at the moment.”

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