Corn and Heart Health Study

Study Overview
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Brief Summary
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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.

Detailed Description
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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.

Official Title
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Evaluating the Effects of Corn Flour Consumption on Cardio-metabolic Outcomes and the Gut Microbiome in Adults With High Cholesterol

Conditions
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Gut Microbiome, Cholesterol, LDL, Cholesterol, HDL

Intervention / Treatment
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* Other: Refined cornmeal flour
* Other: 50/50 refined cornmeal-bran mix
* Other: Whole grain cornmeal flour


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Healthy English and Spanish speaking males and females with elevated circulating cholesterol levels (LDL-c ≥ 120 mg/dL). Individuals with LDL-c > 190 mg/dL will be permitted to participate but must provide a letter from their doctor stating that they are comfortable with their participation in the study. Exclusion Criteria: recent weight fluctuations (> 5 lb in past 3 months), following specialized or restrictive diets (e.g. carbohydrate restriction, veganism) use of supplements (antioxidants, fiber, botanicals) allergies to dairy, egg, wheat, corn or gluten use of antibiotics in the past 2-3 months use of lipid lowering medications regular physical activity ≥ 30 min/d for ≥ 5 days/wk history of thyroid disorders, diabetes, heart disease, cancer, hepatitis, inflammatory conditions and/or gastrointestinal disorders which may impact gut function and metabolism anyone with a fear of needles or blood draws If female, women may not be pregnant or lactating during the study. Unwillingness to comply with study protocols will also result in exclusion from the study. Participants in this study will not be eligible if they are participating in other research studies at the same time.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 70 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Prevention
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: refined-50/50-whole<br>48 g/d of corn flour was delivered to participants in two daily 24 g servings as pita breads and/or muffins via (1) refined cornmeal flour, followed by (2) 50/50 mix of refined cornmeal flour plus corn bran, followed by (3) whole grain cornmeal flour | Other: Refined cornmeal flour<br>* 48 g/d of refined cornmeal flour served to participants as two daily 24 g servings via pita breads and/or muffins<br>Other: 50/50 refined cornmeal-bran mix<br>* 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<br>Other: Whole grain cornmeal flour<br>* 48 g/d of whole grain cornmeal flour served to participants as two daily 24 g servings via pita breads and/or muffins<br>|
| Experimental: 50/50-whole-refined<br>48 g/d of corn flour was delivered to participants in two daily 24 g servings as pita breads and/or muffins via (1) 50/50 mix of refined cornmeal flour plus corn bran, followed by (2) whole grain cornmeal flour, followed by (3) refined cornmeal flour | Other: Refined cornmeal flour<br>* 48 g/d of refined cornmeal flour served to participants as two daily 24 g servings via pita breads and/or muffins<br>Other: 50/50 refined cornmeal-bran mix<br>* 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<br>Other: Whole grain cornmeal flour<br>* 48 g/d of whole grain cornmeal flour served to participants as two daily 24 g servings via pita breads and/or muffins<br>|
| Experimental: whole-refined-50/50<br>48 g/d of corn flour was delivered to participants in two daily 24 g servings as pita breads and/or muffins via (1) whole grain cornmeal flour, followed by (2) refined cornmeal flour, followed by (3) 50/50 mix of refined cornmeal flour plus corn bran | Other: Refined cornmeal flour<br>* 48 g/d of refined cornmeal flour served to participants as two daily 24 g servings via pita breads and/or muffins<br>Other: 50/50 refined cornmeal-bran mix<br>* 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<br>Other: Whole grain cornmeal flour<br>* 48 g/d of whole grain cornmeal flour served to participants as two daily 24 g servings via pita breads and/or muffins<br>|
| Experimental: refined-whole-50/50<br>48 g/d of corn flour was delivered to participants in two daily 24 g servings as pita breads and/or muffins via (1) refined cornmeal flour, followed by (2) whole grain cornmeal flour, followed by (3) 50/50 mix of refined cornmeal flour plus corn bran | Other: Refined cornmeal flour<br>* 48 g/d of refined cornmeal flour served to participants as two daily 24 g servings via pita breads and/or muffins<br>Other: 50/50 refined cornmeal-bran mix<br>* 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<br>Other: Whole grain cornmeal flour<br>* 48 g/d of whole grain cornmeal flour served to participants as two daily 24 g servings via pita breads and/or muffins<br>|
| Experimental: 50/50-refined-whole<br>48 g/d of corn flour was delivered to participants in two daily 24 g servings as pita breads and/or muffins via (1) 50/50 mix of refined cornmeal flour plus corn bran, followed by (2) refined cornmeal flour, followed by (3) whole grain cornmeal flour | Other: Refined cornmeal flour<br>* 48 g/d of refined cornmeal flour served to participants as two daily 24 g servings via pita breads and/or muffins<br>Other: 50/50 refined cornmeal-bran mix<br>* 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<br>Other: Whole grain cornmeal flour<br>* 48 g/d of whole grain cornmeal flour served to participants as two daily 24 g servings via pita breads and/or muffins<br>|
| Experimental: whole-50/50-refined<br>48 g/d of corn flour was delivered to participants in two daily 24 g servings as pita breads and/or muffins via (1) whole grain cornmeal flour, followed by (2) 50/50 mix of refined cornmeal flour plus corn bran, followed by (3) refined cornmeal flour | Other: Refined cornmeal flour<br>* 48 g/d of refined cornmeal flour served to participants as two daily 24 g servings via pita breads and/or muffins<br>Other: 50/50 refined cornmeal-bran mix<br>* 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<br>Other: Whole grain cornmeal flour<br>* 48 g/d of whole grain cornmeal flour served to participants as two daily 24 g servings via pita breads and/or muffins<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| LDL Cholesterol | Serum LDL cholesterol concentrations will be measured at the 0 and 4 weeks for each cornmeal intervention | 0 weeks, 4 weeks | 
| HDL Cholesterol | Serum HDL cholesterol concentrations will be measured at the 0 and 4 weeks for each cornmeal intervention | 0 weeks, 4 weeks | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| 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. | 0 weeks, 4 weeks | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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cholesterol, gut microbiome, gut microbiota, dietary fiber, whole grain