Katy Perry went on a ''cleanse'' to prepare for her Vogue US cover shoot.

The 28-year-old pop star was honoured to grace the cover of the fashion magazine for the first time and stopped at nothing to ensure she looked ''glowing'' for her pictorial - shot by famed photographer Annie Leibovitz - by giving up alcohol for three months and increasing her vitamin intake.

She admitted: ''I did a lot of my own prepping. I kind of went on a cleanse; I did a lot of stuff like vitamins and supplements, I changed my coffee to green tea, I didn't drink alcohol for three months. I was really in the zone, I just wanted to be glowing for that cover.''

It seems the 'Part of Me' hitmaker's hard work paid off as she is extremely pleased with how the photoshoot turned out.

However, Katy insists the glamorous cover - which was shot on a farm in upstate New York - was a team effort and she credited Annie, 63, for being ''fantastic'' to work with.

She added on 'The Tonight Show with Jay Leno': ''She's incredible. It was really fantastic working with her ... She [has] such a great vibe, she's got no ego which is fantastic, and she really lets me be creative as well.''