Millions of acres of genetically modified corn, cotton and potatoes have been planted in the U.S. (Cotton is mentioned here because cottonseed oil is found in many processed foods, and cottonseed meal is fed to cattle.) These foods, which are now in our food supply, have been engineered to produce a naturally occurring pesticide that is supposedly toxic only to insects. There are no long-term human studies to indicate that genetically modified foods are safe. However, rats fed genetically modified potatoes had increased intestinal infections, reduced immunity, and reduced weight of intestine, pancreas, kidneys, liver, lungs and brain. Since you may be unknowingly consuming genetically modified or irradiated foods, you would need dietary supplementation to offset the invisible but potentially negative effects of such foods.