My son was about two and a half at the time, when I noticed his extreme reaction to eating 160b.  We used to use margarine and eat Streets vanilla icecream (I thought by choosing vanilla flavoured products I was avoiding the colours and potential nasties).  When he ate these products he would punch himself repeatedly in the head with a closed fist and also bang his head against the wall.  Obviously as a parent, this behaviour caused me great concern, only to be reassured by people that it is just a phase and he will grow out of it.  This was the start of my journey exploring food additives and the effects they have on behaviour and children.  After buying a book and reading up I decided to cut out products with annatto, and made the switch to Peter's Vanilla Icecream and back to real butter.  Within a very short time this headbanging behaviour ceased.  No parent should have to watch their child physically hurt themselves as a result of what they eat!
As you say, if you notice one reaction to food there will be more.  Every time we used to go to Pancake Parlour and have the two stack pancakes with icecream he would have stomach cramps and diarrhoea that day.  We have visited doctors on several occasions regarding stomach cramps and recurrent diarrhoea.  They wanted him to have blood tests but I was reluctant as he was still young. 

Other difficult behaviours have remained with our son.  He falls in the upper range of normal behaviour, borderline ADHD, shows some autism symptoms and we are off to a Child Psychologist tomorrow for his anger which is escalating into rage.  After buying your books and DVD at the talk and chatting with you I feel empowered to start the RPAH diet.  I've had one appointment with a recommended dietitian  and on Monday our family will start on the RPAH diet.  If he can stop making the silly whoop whoop noises and been argumentative, restless and confrontational then this will be well and truly worth it (and I'm a little excited to see just how I react to certain foods!  My husband not so much!)
Thank you so much for the time and energy that you and Howard put in to educating the general public about food additives.  You are making a huge difference to so many families! - Sarah (report received December 2011)