The Gladiator star, who is dating Metallica drummer Lars Ulrich, has a two-year-old son, but she's interested in expanding on her family.
She says, "I think we should all get around to taking in any child who needs love. I wish there was a better system for foster care and then we would be able to do more for those children.
"It's just heartbreaking even thinking that there are children who are in families that are going through crises and they're not being taken to other families.
"If I had a different job, one that kept me at home, I would seriously consider fostering children from anywhere, especially older children.
"Everyone can fall in love with the cuteness of a baby but having the heart to reach out to the damaged child that has to learn to trust again is more important."