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.
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.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
PREVENTION
Masking
SINGLE
Enrollment
58
48 g/d of refined cornmeal flour served to participants as two daily 24 g servings via pita breads and/or muffins
48 g/d of a mix of 50% refined cornmeal flour and 50% corn bran flour served to participants as two daily 24 g servings via pita breads and/or muffins
48 g/d of whole grain cornmeal flour served to participants as two daily 24 g servings via pita breads and/or muffins
Arizona Biomedical Collaborative
Phoenix, Arizona, United States
LDL Cholesterol
Serum LDL cholesterol concentrations will be measured at the 0 and 4 weeks for each cornmeal intervention
Time frame: 0 weeks, 4 weeks
HDL Cholesterol
Serum HDL cholesterol concentrations will be measured at the 0 and 4 weeks for each cornmeal intervention
Time frame: 0 weeks, 4 weeks
Gut Microbiome Diversity
Fecal gut microbiome communities will be sequenced using microbial DNA extracted from samples at 0 and 4 weeks for each cornmeal intervention. Amplified copies of the 16S rRNA gene will be evaluated for treatment differences in alpha (within-sample richness and evenness) and beta diversity (between-sample community structure). Relative and differential abundance of individual microbial taxa will also be measured.
Time frame: 0 weeks, 4 weeks
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