My 12 year old son was diagnosed with celiac 2 weeks ago. I am overwhelmed with trying to find foods that he can and will eat. He is very picky and does not eat much fruit or vegetables. I was advised that things with natural and artificial flavors have hidden glutens. When shopping at the store a lot of items have natural or artificial flavors even those marked certified gluten free. How can it be certified gluten free if it has hidden glutens in it? When do I know that something is safe for him to eat? Thank you!