My Grandson and ADHD

The topic that I am research is concerning ADHD and the reason for this topic is due to my grandson.  From the time that I took custody of him at the age of 18 months he showed signs of not being able to focus on any one thing.  He would spend a second or two on something and then move to the next object and then the next.  He was into everything around the house, which I know that is typical in children but he was more into things than normal.  Another sign was he constantly made noise verbally, he still does meaning he takes a few words repeating them over and over again non-stop for hours or he will just make a noise of any kind repeating it non-stop.  I had to wait until he was starting school to have him diagnosed for ADHD and since that time he has been taking medication for it.  The medication has made a world of difference, he is more focused and can control himself in many ways better than before however he still makes the noise but not to the degree that he was, but the medication has had its side affects.  The side affects that he has experienced have been from headaches to lack of hunger, at one time he lost 17 pounds and due to that I began looking into other means of treatment for ADHD.  If I can really understand what affects diet will or can make I would rather have him on the diet than the medication, so my research is to influence our world and what would be better for my grandson in the long run concerning his health and living with ADHD.