We pulled our oldest off of red dyes when he was four. His arms had the same rash that my brother gets when he eats too much red dye. My sister-in-law reacts to red dyes with her throat swelling up. So, we pulled him off of the reds. Now, he eats zero artificial coloring as do the younger two. We have found a dye-free "Jell-O" and pudding. We also occasionally buy the dye-free M&M's and other treats. Yummy Earth is a great brand that uses zero artificial anything and they're gluten free.
We've never tried this diet, but we've been eating gluten free since 2001 and we'll never go back to the gluten.
I know my oldest won't go back on the artificial dyes as his skin breaks out in a fierce rash.