"I have to fight that on tour," she says. "I'm 37-years-old, and I don't want to have to censor myself. I can sometimes be a little crass. I'll curse or make a sexual joke and there might be a 12-year-old girl there with her mom who's travelled four hours to the gig. So I'll say: ‘Sorry, mom, hold her ears' and keep going! Being a role model is about being true to myself. Besides, the kids who come to my shows are pretty sophisticated.
"As an artist you have to express yourself," she continues. "I make no excuses for my versatility. I grew up singing classical arias but I love rock'n'roll and jazz standards. I'm just lucky that on this album I had a great producer who used the spectrum of my talents to find a cohesive way to present them to the public."
Menzel is not as self-assured as this makes her sound. In fact, despite rapturous acclaim for her singing and acting, she is wracked with self-doubt. There is even a song about it on her album called My Own Worst Enemy.
"It's about how hard I am on myself," she says, "how I'm constantly trying to get rid of the conversation in my head that always starts whenever I try to do something."
Why is she so insecure? "All performers get on stage because they need to feel love from an audience," she explains. "I might appear confident, but those three seconds before I get out there I'm a mess. But I have to take the risk otherwise I'd be miserable and would feel like I wasn't seeing through my personal destiny."
What goes through her mind in those three seconds?
"I'll think: ‘I have to pee' or ‘I don't know the lyrics' or ‘Why do I do this, this isn't fun.' And then I'll think: ‘Go out and do it for that little girl who came to see you.'"
Menzel describes her struggle to overcome her neuroses as "a battle". "It's a battle to make the positive win out, that part of me that has kept me going since I was a kid that made me feel I had something special to give."
The daughter of a psychotherapist mother and pyjama-salesman father, Menzel's cosy suburban world was shattered by their divorce when she was 16. Another song on I Stand - I Feel Everything -
confronts this turbulent period in her adolescence.
"It's a song about that feeling you get as a kid, coming home to a house that's explosive and you don't know what to expect, whether or not you're going to walk into a room of darkness where someone's screaming at you. It's about that hyper-sensitivity you develop as a kid."
Her parents' divorce was, she says, "a big surprise". Not having her dad at home made her feel bereft. Then she had to contend with a mum who, she says, tended to "wear her heart on her sleeve".
"Sometimes I'd come home to lights out and she'd be up in her room, with a really bad headache. There was that sheer fear of not knowing what to expect.
"I had very loving parents who tried to work through their divorce in the best way possible. Some kids out there have much worse experiences, with alcoholic, abusive parents who they have to tiptoe around. That's really what my song is about."
To stop herself brooding around the house, and to help out financially, Menzel became a singer on the wedding and barmitzvah circuit. Then, in her early 20s, she auditioned for Rent, which became her Broadway debut.
Does her mixture of confidence and self-doubt come from alternately supportive and critical parents? "Well, my dad wasn't critical," she admits, "but he was quite fearful. He wanted me to major in something like business, to have a back-up in case I didn't succeed, because he knew how hard this industry was. My mom said: ‘Forget that, do what you want and you'll be successful.' Now, of course, they're both ridiculous groupies of mine."
Were they shocked by some of the content of Rent, with its tale of life on New York's Lower East Side under the shadow of Aids?
"No," she says. "They're pretty liberal. They loved it. Come on - for Jewish parents, to have their daughter become successful in a Broadway show beats winning an Oscar. It even beats being a doctor!"
There is a third autobiographical song on her album - Gorgeous, about a gay couple she knows experiencing marriage difficulties. Menzel reveals that the track is partly about her own relationship with her husband, African-American actor Taye Diggs.
"I'm more comfortable revealing myself than hiding behind metaphors," she says. "I respond to artists who reveal something of themselves. I don't have to talk about when I last had sex with my husband, although I probably would do that too."
Be our guest. She smiles, but declines the offer. But she does reveal that she wrote the song after a bust-up with Diggs.
"It came out of an argument. We've been together 12 years so I'm not afraid to say: ‘Look, in our industry, if the two of us are still together there will have been times that were amazing and others that were hard work.' People know marriage takes a lot of work."
Sometimes pressures come more from outside than within - the couple were recently victims of racial abuse, receiving hate mail, much of it threatening, but that has, she says, died down now.
"Gorgeous is about my husband and I being an interracial couple and experiencing some..." - she hesitates before continuing - "negative feedback. It's about people having to make excuses to the world. I see it even more with my gay friends. I wanted to write a song about pursuing something you really believe in despite what others think."
One of the things she's pursuing right now is her platonic love affair with Barack Obama. She has even been campaigning on his behalf.
"I feel really attached to this election," she says. "I want the child I intend to have to be able to see a president who looks similar to him or her [ie mixed-race]."
Will her kids be brought up Jewish?
"My god, this is a tough interview," she laughs. "I am a Jewish woman and I feel strong connections to my culture and, so yes, I would like to bring them up with knowledge of the stories and awareness of the history. I'm just not sure about the rest. I'm a spiritual person, not a religious person."
Stand is released by Warner Bros on October 13
Snapshot
Born: May 30, 1971. Long Island, New York. Mother, Helene, a psychotherapist; father, Stuart, a pyjama salesman.
Career highlights: Broadway debut in 1996 in Rent. Won a Tony award in 2004 after starring in Wicked on Broadway. Played in Wicked in the West End in 2006. Released three albums.
On being Jewish: "I feel strong connections to my culture. I'm a spiritual person, not a religious person."
"I feel comfortable being all those things," she says. She cites Bette Midler's as an example of a successfully eclectic career. "One minute she's singing Boogie Woogie Bugle Boy, the next she's Janis Joplin [Midler played a character based on the late wild '60s rocker in 1979 movie The Rose] or doing some comedy shtick."