From experience with our son, the parents need to eliminate all processed foods. No artificial colors, flavors, sweeteners, preservatives, etc. No low-fat, low-cal, fat-free, diet anything. 100% whole wheat. No fruit juices. Real food is the key. Combine dietary changes with extra exercise and physical stimulation during learning time and the kids will thrive. Also, a high quality multi vitamin and extra D, B, and omega 3s.
I was waiting for someone to bring up the OTHER junk we feed our kids. Good for you, and especially good for your son.
It's a real battle to eat right in the face of so much VERY attractive, widely advertised garbage.