Approximately 70 percent of foods in our supermarkets contain genetically engineered ingredients including products made from these most common genetically modified foods. 1. Soy: soy flour, lecithin, soy protein isolates and concentrates (protein shakes).ead: Is Monsanto's GMO Corn Causing Gluten Intolerance. Antibiotic resistance —Most genetically engineered plants carry antibiotic genes to make them disease resistant. These genes could reduce the long-term effectiveness of antibiotics to fight disease.