My son is on the autism spectrum (Asperger). What we’ve found in our own experience is that the fake sugars, glutin and food colorings do make a difference in his ability to control himself.
When you look at the modern diet and compare it to historic diets, we are markedly different in what we are feeding our children. Previous generations didn’t grow up with so many grains... especially not grains nearly devoid of nutritional content. They didn’t have the loads of sugar added to every food including meat and vegetables. Hell, the next time you’re in the store, try to buy your normal foods and avoid high-fructose corn syrup... it’s in everything!
I can only go by our experience and that of our friends with similar issues. Changing the diet changes the child. That doesn’t mean it affects all children the same way. We have many friends who seem to subsist on real “junk food” just fine. But if you have children somewhere on the autism spectrum, diet is very important to controlling its effects.
I personally believe that the autism manifestation is mainly just a different way of being... it’s not a problem, really. Your doctors need to be able to focus like a laser for hours at a time. You also need those people who can focus on multiple things at once and thrive in what others find to be chaos (like pilots). I think I would be diagnosed on the autism spectrum by current standards. However, the degeneration of our diets is contributing to these people coming unglued and being disruptive in school and society.
Just my experience and opinion.
That is great that you found something that works for your child. Unfortunately, it may have nothing to do with autism. Autism is diagnosed based on a collection of behavior. The problem is, much of that behavior also occurs in other disorders. It may be the case that something is called autism when it is, in fact, it is an entirely different disorder. In your case, it could be a dietary/digestive/etc.disorder (again, that looks like autism because no behavior is unique to autism).
At the end of the day, autism is not a disorder of diet or digestion and, therefore, is not resolved by changing a diet. Regardless, if you’ve found something that works for you, that’s great and, in the end, the label is rather unimportant.