Yes diet and supplements can make a huge difference. I just started my son on the Feingold Diet a month ago and already see a so much more peace. No more angry outbursts unless we slip up on the diet. And it really isn’t cutting things that they like out. Just switching them out with something different. But read on adhdnaturally.org
They have a whole pack that we are about to start on. If you don’t do supplements you will be hard pressed to get all the needed nutrition in them each day.