4 1/2 year old behavior that is confusing me

[guigal]

Thank you for reading, I am feeling a bit desperate for input.  I am confused with my 4 1/2 year old son.  He is now at his 3rd preschool because I thought it was a school thing...  he will not participate at school, he will hit other kids and the teacher when frustrated and say bad things.  He seems overly stimulated, distracted and frustrated to be at school.  He only wants to do his own thing.  Some days are perfect though.    He has a lot of energy and seems to do better when he is on a wheat and sugar free diet.  After he eats wheat or sugar he acts like this other personality.  Is it all just food?  I have had him tested for developmental issues twice this year and he is fine.  There are no issues when he is working one on one, just when he is in larger groups.  I don't know what to do.  Any ideas?  I am a structured stay at home mom and reward him with good behavior.  I have been down the ADHD path but it doesn't seem to add up with his ability to be normal at home but not at school.  Please help someone.  

[LRM1021]

Many drs disavow this, but there are so many parents out there who will swear that when their children eat certain foods -- especially dairy, wheat, gluten-- their behavior is awful. I would stick to the diet change if you notice the difference-- it certainly can't hurt.

In my child's case, it does not matter what he eats-- if it did, I would avoid it:)

[laurabed]

have u had him tested for diabetes. I have a friend and when she gives her child anything with sugar she will go like what your little lad is. Get him tested for it so if it comes bk ok  you will have to think about giving him a wheat and sugar free diet or try and get tests done to rule things out
hope this is a bit of use to u and good luck.