Following a gluten-free diet includes watching out for hidden sources of gluten, which can be in condiments such as soy or bean sauce common in Chinese recipes, or in the coatings and fillers in vitamins and medications, registered dietitian Tamara Duker Freuman writes. Crumbs inside a toaster or peanut butter and spreads used by others in a household can contain transferred gluten from other products. U.S. News & World Report/Eat + Run blog (9/11)