The actor was rushed to hospital before shooting his new movie Jobs about the late entrepreneur Steve Jobs after embarking on a fruit-only diet for the biopic, favoured by the Apple co-founder who died of pancreatic cancer in 2011.
He told USA Today newspaper at the premiere of the movie at the Sundance Film Festival in Park City, Utah on Friday (25.01.13): "First of all, the fruitarian diet can lead to like severe issues. I went to the hospital like two days before we started shooting the movie. I was doubled over in pain.
"My pancreas levels were like completely out of whack. It was really terrifying ... considering everything."
The Two And A Half Men star - who is dating 29-year-old 'Ted' actress Mila Kunis - studied hundreds of hours of footage of Steve for the role and claims he discovered they had a lot in common.
Ashton, who is also an established investor in Silicon Valley, said: "We both have a ravenous interest in the tech space. He's a guy that failed and got back on the horse. 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."
The movie is set to be released in April.