The jOBS star, 34, followed a fruit-only diet to get into character as the late visionary for the biopic, which premiered Friday night at the Sundance Film Festival.
But channeling Jobs's reported diet took a toll on Kutcher's health: Two days before filming began, he was admitted to a hospital for pancreas problems, according to USA Today.
"First of all, the fruitarian diet can lead to like severe issues," Kutcher said following the movie's screening. "I was like doubled over in pain."
It's been more than a year since Jobs died in October 2011 after battling pancreatic cancer, a fact not lost on the actor.
"My pancreas levels were completely out of whack," he recalled. "It was really terrifying ... considering everything."
The biopic, due to arrive in theaters in April, follows Jobs and co-founder Steve Wozniak's rise to tech stardom from their humble beginnings working from a Palo Alto, Calif., garage.
"He's a guy that failed and got back on the horse," Kutcher said. "I think we can all sort of relate to that in some place in our life where we are moving forward with something and we fall down. You have to have the guts to get back up and go again. I think I share that as well."