Can food dye be a risk factor for ADHD? Research points in that direction. Studies show that food dye and preservatives can affect the behavior of some children.
For example, food which contains Yellow 5 causes human beings to excrete zinc through saliva and urine. If a person is already diagnosed with ADHD, it seems the speed with which zinc is lost actually increases.
According to experts, this is why zinc is important:

• Hundreds of enzymes that affect metabolism of protein, carbohydrate, alcohol and fat depend on zinc
• It is critical for the healing of wounds
• It is critical for bone strength and many other crucial physical
  functions
• It is needed for healthy cognitive functions

Even a minor deficiency can cause mental and physical problems.
It isn’t only Yellow 5 that creates problems. All the man-made dyes are loaded with dangerous contaminants. Included in this list are arsenic, lead, mercury and benzidine,
which is carcinogenic.
Taken individually, they are dangerous enough. But a cocktail of such ingredients could be harmful to a child with a developing brain and nervous system.
Since lead targets the oxygen carrying protein in red blood cells, it can, over time, attack one’s nervous system.
Mercury can negatively impact the neurological development of infants as well as
children.
Arsenic is responsible for causing cancer, headaches and confusion.
Food dye may not contain large amounts of any of these, but in a small child’s body, the effects might be cumulative.
A study was conducted in Great Britain in 2007 by their Food Standards Agency. The study involved giving 3, 8 and 9 year olds three different types of drinks, using
various artificial colorings. There was also a control group given a placebo,
which had no additives. Afterwards, the children’s behavior was observed and
evaluated by parents and teachers.
Researchers discovered that the children given the drinks with artificial coloring additives
displayed hyperactive behavior, and the conclusion was reached that food dyes do
show an adverse effect on behavior.
The FDA is now investigating the connection between ADHD and food dyes.
The main dyes they are concerned with are Red 40, Yellow 5 and Yellow 6. Not surprisingly, they are found in many of the foods marketed towards consumption by children.
What has research shown? Once again, that the zinc levels in some children are depleted enough to cause hyperactive behavior.
Red 40 alone can cause:

• aggressive behavior
•  temper tantrums
•  anxiety
• inability to concentrate and fidgeting.

Interestingly, here are some common symptoms of what mental health practioners refer to as ADHD:

• Difficulty paying attention, makes careless mistakes in school
• Temper tantrums
• Anxiety (although this is sometimes diagnosed as “anxiety disorder” but the result is the often the same – placing the child on psychiatric
  drugs)

This is a familiar list of symptoms, too often treated with dangerous psychotropic drugs instead of researching natural means to eliminate such behavior. It has been said that
eliminating food dyes from the diet of a child can make a definite difference.
While there may be natural ways to deal with behavior problems, we as parents and grandparents are faced with the ethical misconduct of psychiatry and the pharmaceutical
companies. Their brutal use of our children as personal moneymakers must be
dealt with before another generation is irreversibly damaged.
http://www.feingold.org/yellow5.php