Your personal statement is your entry into university, pretty much, because it determines (amongst other things, like grades in hand and predicted grades) whether you get an interview or not.
I'm of the opinion that all work experience should be mentioned, regardless of how long you did it for - the key thing you need to remember is to always relate it back to why doing it should make the university consider you as a prospective student. So, just think about how your experience at Vitalise makes you a good candidate for medicine... what did you learn from it? Most people can relate such things to important skills such as improvement in communication, working with different people, increases in confidence, better team work etc. As long as you can relate it to something relevant, mention it.