The anti-gluten-free movement just got a new weapon to add to its arsenal: evidence to confirm that, yes, many people are eating gluten-free food without medically needing to.There was no increase in the number of people being diagnosed with coeliac disease between 2009 and 2014, but the proportion following gluten-free diets more than tripled in that time, according to a new study.Researchers said the gluten-free trend may partly be "because of a public belief that the diet is healthier".The increased availability of gluten-free food, which is now commonplace in even the most mainstream supermarkets, was also said to be behind the trend.Eating gluten-free is medically necessary for sufferers of coeliac disease , whose adverse reaction to gluten can cause diarrhoea, abdominal pain, weight loss, tiredness and bloating. However, it's often been debated whether a gluten-free diet is beneficial for those without the condition.The researchers also said the number of people with "self-diagnosed gluten sensitivity” has risen, The Times reported . These people claim to have “improved gastrointestinal health” when they avoid gluten, but don't experience the symptoms typically associated with coeliac disease.The study, published in the Journal of the American Medical Association , used data from the National Health and Nutrition Examination Surveys, which measure health and nutrition in the U.S.Gluten-free diets have become similarly popular in the UK, with £184 million worth of gluten-free products being sold in 2015 – a 15% increase on 2014, The Times reported . And 8% of British people now avoid gluten for "health" reasons – more than the 5% who do so because of an allergy or intolerance, according to a report by retail analyst Mintel The latest U.S. study came shortly after a café in Dublin, Ireland, warned customers that if they want to order gluten-free food, they will have to produce a doctor's note.Paulie, from the White Moose Cafe, posted on its Facebook page : "This morning a girl asked us if we did gluten-free pancakes and when we asked her if she was a coeliac, she didn’t even know what the word meant and then proceeded to order regular, gluten-rich pancakes anyway."From now on, guests who demand gluten-free food are required to produce a doctor’s note which states that you suffer from coeliac disease. Guests following a gluten-free fad, who don’t even know what gluten is, can cop the f*ck on and eat regular food like everybody else."The post sparked a backlash from some, who said it was "disgusting" that genuine coeliac sufferers will have to carry proof of their illness.But Paulie didn't seem fussed, and he said business has boomed since his original post.