Denzel Washington thinks Whitney Houston's death is an "example to keep it together."

The 57-year-old actor believes his friend -- who was found dead in the bathtub in her Beverly Hills hotel room in February -- didn't realize the terrible toll her addiction to cocaine and crack had taken on her and should be a warning to all actors and musicians not to be seduced by the dark side of fame.

He said: "Whitney was such a sweet, sweet girl and really just a humble girl.

"It's more of an example to me or the rest of us to keep it together. I was listening to her song 'I Look to You'. It's prophetic.

"Maybe I'm speaking out of line. Maybe she thought she could have one. And then the next thing you know, her body was betraying her. She didn't know that her body was aging quickly. She couldn't take it. Your body can only take so much.

"Some people survive [Hollywood and fame], and some people don't."

Washington thinks Houston's story was particularly tragic because she had previously managed to overcome her addictions, but he accepts it is hard to avoid the temptation to relapse.

He added to GQ magazine's October Style Playbook: "Whitney was my girl, and she had done so well in recovery. And that is the toughest part about addiction. And that was a monster drug that got a hold of her, it was a mean one. You can't go back to that one. Nobody beats that.

"I look at people -- and I don't think I'm speaking out of line -- Samuel L. Jackson, I've known for thirty-some-odd years, he was down at the bottom. And he came all the way back. And when he cleaned up, he never looked back. But he can't have that beer, because it might lead to the tough thing."