The 51-year-old music mogul got a taste for the beverage – which is made up of lingonberry, chokeberry, aronia juice and acerola berry – when he was recently in Miami and asked for the concoction's ingredients to be imported from around the world for when he is on the road in America watching 'X Factor' auditions.
A source told the Daily Mirror newspaper: "He's obsessed with staying healthy and wants to look after himself. The drink is an extension of that.
"It is not cheap to make and involves lots of hard-to-buy fruit which we need to take on the road. But for someone like Simon it is not a big deal if it costs a lot.
"He is also eating lots more salad and raw vegetables and has them cut up in his dressing room to try to avoid the chocolate biscuits he used to snack on."
Last year, Simon's close friend Amanda Holden revealed he was "the healthiest he's ever looked" after drinking "green swamp juice" and vitamin juices.
She said: "Simon's make-up artist is great because she brings in loads of vitamin juices, which help to keep up energy levels during long audition days. Simon has his green swamp juice in a mug.
"He's into these health smoothies and is always giving away recipes. I actually think this is the healthiest he's ever looked. He's lost weight, he's really fit, his skin looks good and his eyes are shiny. He's either in love or it's the herbs!"
