The Dietary Guidelines for Americans recommend that children and adolescents "consume whole-grain products often; at least half the grains should be whole grains." Few, if any studies, examine the benefit of whole grains on the health of adolescents. The purpose of this study is to determine if adolescents eating diets rich in whole grains vs. diets rich in refined grains (i.e., a typical diet) have improved markers of digestive and immune health.