I don't follow it strictly, but I do avoid sugar and the listed preservatives for the most part. DH thought I was being pedantic at first, but he has now seen the resulting change in behaviour often enough to know when DS1 particularly has had sugar or a preservative he reacts to. When I told DS1's paed recently that I avoid them she said straight away that he'd be very sensitive to those things - DH was there to hear that too, but he had already been convinced by then.