Juice cleansing, a dieting trend popular among celebrities like Beyonce and Coleen Rooney , can have negative effects on your health in as little as three days, according to new research. Scientists warn that this fibre-free diet may increase bacteria linked to inflammation in the gut and mouth. A US study, published in the journal Nutrients, found that a diet consisting only of vegetable and fruit juice for three days can cause changes in gut and oral bacteria associated with inflammation and