Has anyone done/or doing the failsafe eating/diet??

DD1 is 6.5yo and has been diagnosed with ADHD and I'm considering cutting out artificial preservatives, colours and flavours from her diet. I've looked at the failsafe diet briefly and got an idea of what is involved and what would need to be eliminated and I just couldn't cut it all out as DD is limited now on what she will and will not eat so I'm thinking of trying it within the above areas to see if a difference is noted.

Interested to hear feedback and also to ask a few questions.