Propionic acid (PA) is used as a preservative in foods such as cheeses, baked goods, or additive for artificial fruit flavors. The U.S. Environmental Protection Agency considers it safe and therefore, has no limitation on its use. Since PA has been shown before to serve as a substrate for glucose production in the liver, the purpose of this study is to find out if PA intake causes changes in levels of glucose, insulin and other important hormones following a meal.