The investigators have hypothesized that dietary flavonoids reduce insulin resistance and subclinical inflammation secondary to reductions in intestinal inflammation and permeability and that these events are mediated through alterations in gut microbiota composition. To test this hypothesis, 30 overweight/obese men and women will be provided two well-controlled diets that are identical in macronutrient content (Protein, 17% en; Fat, 30% en; Carbohydrate, 53% en), but differ markedly in flavonoid content (Low Flavonoid Diet, 10 mg/1000 Kcals; High Flavonoid Diet, 340 mg/1000 Kcals). All meals for both diets will be prepared and fed for 6 weeks each in a randomized cross-over design with endpoints determined in duplicate during the last week of each diet period.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
TRIPLE
Enrollment
30
A prepared diet consisting of whole foods with a macronutrient composition of 17% en from protein, 30% en from fat and 53% energy from carbohydrate and containing high levels of dietary flavonoids including anthocyanins, flavanones, flavan-3-ols, flavonols, flavones, and polyflavonoids.
A prepared diet consisting of whole foods with a macronutrient composition of 17% en from protein, 30% en from fat and 53% energy from carbohydrate and containing low levels of dietary flavonoids including anthocyanins, flavanones, flavan-3-ols, flavonols, flavones, and polyflavonoids.
Utah State University, Center for Human Nutrition Studies
Logan, Utah, United States
Fecal calprotectin
Primary endpoint for intestinal inflammation
Time frame: 6 weeks
Serum C-reactive protein
One of two primary endpoints for systemic inflammation
Time frame: 6 weeks
Serum soluble tumor necrosis factor receptor-1
One of two primary endpoints for systemic inflammation
Time frame: 6 weeks
Serum insulin
Primary endpoint for insulin resistance
Time frame: 6 weeks
Fecal microbiome composition
Includes relative abundances of operational taxonomic units and assigned taxonomy as well as alpha and beta diversity measurements
Time frame: 6 weeks
Fecal short chain fatty acids
Measure of fecal microbiome metabolic capabilities and includes acetate, propionate, butyrate, valerate and caproate.
Time frame: 6 weeks
Fecal eosinophil protein X
Secondary endpoint for intestinal inflammation
Time frame: 6 weeks
Fecal myeloperoxidase
Secondary endpoint for intestinal inflammation
Time frame: 6 weeks
Intestinal permeability by four sugar differential absorption test
Secondary endpoint for intestinal inflammation
Time frame: 6 weeks
Serum endotoxin
Secondary endpoint for intestinal inflammation
Time frame: 6 weeks
Serum interleukin-6
Secondary endpoint for systemic inflammation
Time frame: 6 weeks
Serum soluble tumor necrosis factor receptor-2
Secondary endpoint for systemic inflammation
Time frame: 6 weeks
Serum fasting glucose
Secondary endpoint for insulin resistance
Time frame: 6 weeks
Calculated Homeostatic Model Assessment-Insulin Resistance
Secondary endpoint for insulin resistance
Time frame: 6 weeks
Serum C-peptide
Secondary endpoint for insulin resistance
Time frame: 6 weeks
Plasma lipids
Secondary endpoint for insulin resistance. Includes LDL-cholesterol, HDL-cholesterol and triglycerides
Time frame: 6 weeks
Blood pressure
Secondary endpoint for insulin resistance. Includes systolic and diastolic blood pressure
Time frame: 6 weeks
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