Dr. Rebecca Carey admits to being a little embarrassed about what her son, Mark, eats every day. Hamburger patties for breakfast, or bacon. A pack of raisins and a cookie for lunch; a turkey and cheese sandwich “if I’m lucky,” says Carey, but it usually comes back home. His favorite dinner is fish cakes and pasta, but all vegetables remain firmly untouched. It’s the kind of diet — low in fruits and vegetables, high in carbs — that a doctor like herself might caution against. But it’s also low in milk, sugar, and artificial food additives — all things Carey believes worsen 10-year-old Mark’s attention deficit hyperactivity disorder, or ADHD, symptoms.