We did Feingold for about 6 months when my son was in 2nd grade. We did see some improvement although minor. It was pretty expensive to buy only products that didn't contain certain additives, certain colorings, certain enzymes (grapes, apples, etc.) It took me months to determine which products I could buy and which I could not. The cost differential is pretty substantial and some things are nearly impossible to find unless you want to buy online and also pay shipping. We either had to have everyone in the family on it (costly) or single him out and segregate all the food.
It helped a little - but it also added a level of aggravation, frustration and difficultly for my son. If he went to a friend's house he's have to bring his own cookies and couldn't eat lunch with the friend, he couldn't partake in typical birthday party fare, any party, BBQ, gathering became a major issue. If we had seen a huge difference in my son we would have continued. (My friend's son is autistic and he does amazingly well on a gluten, addititve free diet - so I can understand completely why she goes through all the aggravation.)
We did learn through the process that my son is senstiive to artifical colorings and not really to other additives. So now we try to avoid brightly colored foods and things along those lines. But try to find a slurpee in the middle of a hot summer day that doesn't have artificial colorings...
My son is now finishing 6th grade. He's also on focalin - still on only 10mg because it seems to work - we've never increased his dose and he's now 5'7" and more than 150 lbs. When he goes off it then back on it (after vacations, when school starts in Sept) he is cranky at first. He'll get a headache late afternoon when it begins to wear off. But when he's on it steadily through the school year he doesn't have a crankiness or the late afternoon headaches. We've also found that keeping him hydrated and making sure he has healthy late afternoon snacks as the meds wear off helps alot too. We've learned to get out in front of the need to eat & drink as it wears off.
I know two families who are pretty strict adherants of Feingold. Both of them began to follow it for their daughters. I've had both daughters in my Sunday school classes and I can tell you it's not working as well as they think it is. Both girls are still not able to really focus - one has significant language based learning disabilities to the extent that she's a year behind in school. My son also has language based learning issues - but since we decided to keep him on the medication and not waver (we had years where we let him go off the medicine for a few months as a "trial") he's done wonderfully. For the first time in his life he's in the middle of the average score for language skills assessement and reading level - he used to be in the bottom 5%. HUGE! I attribute that greatly to the steadiness of his medication which enables him to stay on task. He also now realizes the difference in his ability to focus - as a matter of fact we almost forgot his medicine this morning - but on the way out the door (for his first final exam ever) he stopped and asked for his medicine. He used to fight it and thought he was the only kid taking medicine - now he's old enough to realize how much it helps him.
I used to be resistant to the idea of having to give him medicine. But I realized that I use coffee as a way to address my ADD ( I have a huge problem focusing) and many people use other drugs like smoking pot or taking speed to help them zero-in on their tasks. Better he's using controlled medication to assist him in paying attention and staying focused, than it is to have him begin to self-medicate one day in the future.
I know there are a lot of people who have negative ideas about "chemicals" and using artificial stuff like pharmaceuticals. But there are so many instances where it's beneficial - such as my mom who had her thyroid removed as a teen taking synthroid for the last 65+ years to replace the thyroid hormone, diabetics taking synthetic insulin and other drugs that helps the insulin to be processed more gradually. Consider an insulin pump. It's very aritificial - but it releases a low steady does of insulin all day long and is much closesr to how the body should do it naturally if it could.
When something is not working correctly in our bodies and there is a way to address it and make our bodies function more normally why wouldn't we do that? Clearly people who struggle with staying on task, paying attention, etc. do better when they have a chemical aide to keep their mind on track. Chemistry is not bad when used properly. Let's face it, our body is made of chemicals, water is H20 - a chemcial compound.
I would be interested to see if Feingold works better for you than it did for us - and how the practicality of it works out. Please let us know!