Instagram reaches 150 million monthly active users with adverts soon to appear on the site Five Instagram users to watch out for: Jamie Oliver Jamie Oliver was an early adopter of the photo sharing site and uses it to post images of his mouth-watering meals with handy links to his recipes. He is also particularly fond of photographing his cherubic looking children. Oliver is a prolific poster- and has accrued more than 1.3 million followers. Aside from his enthusiasm for anything foodie he also likes to post musings about life in general. Take his recent missive about Richard Curtis's new film 'About Time': "[It] made me laugh, cry and want to appreciate life. ... it was also superbly sentimental which I think most men aren't very good at." Barack and Michelle Obama Barack Obama's Instagram account is run by his staff but it still has plenty of candid photos. The American president joined the site during his 2012 election campaign. Michelle Obama made her Instagram debut during a trip to Africa earlier this year. She introduced the White House's new dog Sunny on Instagram and has also posted several family photos. Her latest video shows her dancing with schoolchildren. Madonna No sooner had Madonna joined Instagram than she was being warned about breaking their rules. No explanation was ever given as to how she had flouted the 'Community Guidelines' but that hasn't stopped the singer from testing the boundaries. She mainly posts 'selfies' (images of herself) but likes to mix it up a bit with political messages. In July she posted a photo of a note she had written to her fans which read: ""I am an artist and a freedom fighter! I have always fought for Freedom of Expression and human rights in general! If you don't like what I have to say or do then simply stop following me on Instagram!. Her most recent post urges the United States not to intervene in Syria "for the sake of humanity." Syrian Presidency Bashar-al Assad joined Instagram in July as part of a bizarre propaganda drive to gloss over the devastation wrought by the country's civil war. Bashar is pictured doing various everyday presidential tasks while his wife Asma helps the needy. She even had time last week to sit down with Syria's top performing schoolchildren. Nasa The official Nasa Instagram account was only launched last week but already has nearly 100,000 followers. It was timed to coincide with the take-off of a robotic research mission designed to orbit the moon. It photographed the launch as well as a beautiful view of the earth from space. Nasa says its account will provide a "comprehensive view of the agency by sharing new and historic images and videos."