"Now was once considered very rare, but in the last probably 10 to 15 years it has become quite common. It's now being diagnosed 20 times as often as it was 30 years ago. Why is this happened? We really don't know. Some people think it might be due to a change in what we're eating or the types of foods we're eating. But really we have no idea why this increase has occurred. This increase parallels other s like and disorders."