For example, Upshaw remembers when, in the late 1970s, Nestle angered consumers with a baby formula product it claimed to be a healthy alternative to breast-feeding.
"It's relatively unusual for a CEO to be as outspoken as Mackey has been," said Upshaw. "Because any time you weigh in to something political, you're bound to have loyal customers who will question [your] point of view, and that can have a very negative effect."
Upshaw added that Mackey's op-ed may have done more harm than might be typical because of the unique makeup of his clientele.
"You have more activist consumers going to Whole Foods than other stores," said Upshaw. "They're not just simply expressing an opinion, they do something about it.
"These are people who have already gone out of the way to find a place that is more expensive to buy certain types of food," he said. "So in theory, they might be more willing to take the action to go somewhere else if they don't agree with Mackey."