You may have heard that the safety of artificial food colorings has come into question and that public health officials are considering whether their use may contribute to hyperactivity and other behavioral problems in children. Here is an article from the New York Times detailing the subject and the FDAs history with food dyes.
There is a quote in this article from a behavioral pediatrician suggesting that diet being related to behavior is mythology. I wont go so far as to call this statement false but I will call it irresponsible. If it's POSSIBLE that an unnecessary food additive is causing a problem for your child, WHY NOT eliminate it from the diet? There are absolutely NO benefits to keeping it in the diet and, at the very least, the possibility that the dietary adjustment would help. WHY NOT!?! Children are not suffering from a deficiency of Red #40. Cut it out and just see what happens.
The human body, which co-evloved with REAL food knows exactly what to do with real food substances. It is also strong and smart and will try very hard to process things it doesn't recognize as foods like artificial dyes and flavor and even plastics (yes, plastics) that are found in fake foods like processed cheese slices. Unfortunately, when it is forced to constantly digest these fake foods, the wear and tear on the digestive system eventually forces the body to store chemicals in adipose fat or, worse, in fatty organs like the liver and the brain.
How do we know if something should be eaten or not? If you couldn't grow it, raise it, milk it or process it yourself in your kitchen, don't eat it. You're body is not built for it. As soon as someone gives me the recipe for homemade Velveeta, I will reconsider.