Have you had experience with the use of supplements or diet modifications in the treatment of SPD?
The short answer is YES. I have seen kids with apparent SPD make significant improvements after starting everything from fish oil supplements to the GFCF diet.
The long answer is that if the kids respond to these diet modifications, it MAY have never been SPD in the first place. Most likely (in my opinion) it was a food allergy or unmet dietary need all along. Their discomfort maxes out their sensory system, so they appear to have SPD. If you have success with dietary modifications, I recommend full food allergy testing to see if there are any other issues. Now, without a doubt, there are kids who have both—SPD and diet issues—including my very OWN daughter! In that case, treat both.
It’s great that you are considering all the possibilities. SPD can easily be confused with many other diagnoses. To compound the confusion, it also goes hand in hand with many other diagnoses.