Documentary maker Louis Theroux has said years of hanging out with swingers and porn stars has made him "a puritanical person".

The 42-year-old presenter, who has shared a hot-tub at a swingers' party and filmed in a brothel, has just returned to Los Angeles to film some of the porn stars he met for his Weird Weekends show in 1997.

He told the Radio Times: "A lot of performers, I would say most, have had some chaos or turbulence in their upbringing, perhaps connected with their parents. But the porn industry then exacerbates it, stores up more problems."

Theroux, who regularly moves in with his subjects while making his films, said his new film about the porn industry was very different from the one he made as a young man.

"I've discovered I am quite a puritanical person."

He said he now believes there is a better argument for legalising prostitution rather than pornography.

"It seems a more humane profession," he added.