One of the most interesting books I have read lately is "The Unhealthy Truth" by Robyn O'Brien. It is a must read if you have children with food allergies or behavioral problems. She has children with food allergies, and is trying to dig deep and get to the bottom of the allergy epidemic. She explores many theories, the biggest one being GM foods.
Genetically modified foods were released into our supermarkets in 1994. Since then, there has been a surge in food allergies (400% increase). Maybe it is a coincidence. Maybe not. We don't know because there is no research being done, and no regulations in place. Many countries around the world have banned GM foods, or required them to be labeled. Many countries have also banned the use of artificial colors.
Kraft has taken artificial colors and flavors out of their foods in the U.K., but not the United States. Mars and Coca-Cola have followed suit and taken additives out of their U.K. products. Many other countries have banned the use of artificial dyes and additives that have been proven to be harmful.
Another interesting thing I learned in this book is that mast cells (the cells involved in allergic reactions) are linked to a possible increase in pancreatic cancer, according to an April 24, 2008 study published in the New England Journal of Medicine.
Also, If you haven't looked into the feingold diet, you should. I have read hundreds of online forums and SO many mothers swear that going off of artificial colors, flavors, chemicals, and preservatives completely changed their child's life. If you don't want to pay to join, you can do some googling to find out more about what is allowed on the feingold diet.
Oh, and buying organic is the only way to be assured that you are not eating genetically modified food.