The 27-year-old actress admitted that she was worried about portraying the dark and complicated life of the "Deep Throat" star, even going so far as to think that it could "ruin" her career.
"I read the script and I was like, 'Wow, this is the riskiest thing that's happening [in Hollywood] right now,'" she told the mag.
"The first thing you think about is that it could have ruined my career. At the same time, I was like, 'This is my chance to show them, to show the industry, to be recognized.'"
Seyfried wasn't coy about her own thoughts on sex either, telling Elle that sexual attraction has been important in her previous relationships -- she's dated heartthrobs Dominic Cooper, Josh Hartnett and Ryan Phillippe.
"Everybody I've dated I've been sexually attracted to immediately," she said. "Sparks don't grow—your vagina doesn't become more inclined to wanting someone just because you're around them."
As for her break up with her "Mamma Mia" co-star Cooper, Seyfried said she'll they'll always be friends.
"We love each other," she said. "He'll always be in my life regardless of what his girlfriends or future wife think. I'm never going to be with a guy that can't deal with my friendship with him."