Dietary fibers are extremely complex and foster health in a variety of ways that are not fully understood. The Adequate Intake of fiber (14 g per 1000 kcal consumed) is based on data that strongly support a relationship with cardiovascular disease prevention (Slavin, 2013). While cereal fibers have been shown to be most effective at reducing cardiovascular disease risk (IOM, 2002), the components of dietary fiber (e.g. germ, bran) that exert this effect remain inadequately studied in cardiometabolic outcomes. Further, specific types of dietary fiber (natural and synthetic) have been shown to increase beneficial microbial species in the gastrointestinal tract, which are accompanied by improvements in inflammatory and metabolic disease markers. Very little is known about how isolated or intact fiber in whole grains solicit beneficial health effects via microbial mechanisms. Our goal is to study both changes in cardiometabolic outcomes and the gut microbiome after consuming different types of corn-based meals.~Aim 1: To evaluate cardio-metabolic outcomes (primary outcome: LDL cholesterol) after consuming 48 g/d of whole grain corn flour, 50% refined corn flour + 50% corn bran derived from whole corn meal, and refined corn flour for 4 weeks in adult males and females with elevated LDL cholesterol in a crossover design.~Aim 2: To evaluate changes in the gut microbiome after consuming 48 g/d of whole grain corn flour, 50% refined corn flour + 50% corn bran derived from whole corn meal, and refined corn flour for 4 weeks in adult males and females with elevated LDL cholesterol in a crossover design.
The purpose of this study is to investigate the effects of 3 different corn flours: (1) whole grain corn flour, (2) 50% refined corn flour + 50% corn bran derived from whole corn meal, and (3) refined corn flour, on cardio-metabolic outcomes and changes in the gut microbiome.