Mediterranean Diet and Weight Loss: Targeting the Bile Acid/Gut Microbiome Axis to Reduce Colorectal Cancer
NCT04753359
Summary
A Mediterranean Diet (MedDiet), a largely plant-based dietary pattern, is relevant to CRC prevention and microbial production of anti-cancer metabolites in observational studies. A MedDiet can shift BA metabolism as shown in primates and when combined with calorie restriction, shows superior adherence and weight control in humans, given its palatability. To date, no studies have tested in an RCT the effects of a MedDiet alone (MedA), WL through lifestyle intervention (WL-A) or a calorie-restricted MedDiet for WL (WL-Med) on the BA-gut microbiome axis and its relevance to CRC prevention among AAs. A multidisciplinary team combining expertise in psychology, nutrition, microbiology, molecular cell biology, computational biology, medicine and biostatistics, proposes to conduct a four-arm RCT in which 232 obese AAs, 45-75 years old complete one of the following 6-month interventions: Med-A, weight stable; WL-A, calorie restriction with no diet pattern change; WLMed; or Control. The investigators will use samples and data collected at baseline, mid-study (month-3) and post-intervention to compare the effects of the interventions on 1) Concentration and composition of circulating and fecal BAs; 2) Gut microbiota and metabolic function; and 3) Gene expression profiles of exfoliated intestinal epithelial cells.
Eligibility
Inclusion Criteria: * Men and women 45-75 years of age * Self-identify as AA * BMI 30-50 kg/m2 * Willingness to participate in all procedures including maintaining weight/current physical activity if randomized to Med-A/Control * Willingness and ability to provide informed consent * Willingness to be randomized * Understands English * Has access to a phone * Plans to reside in Chicago for the next 8-10 months. Exclusion Criteria: * renal disease * autoimmune disorders * immunodeficiency * malabsorptive disorders * significant gastrointestinal and/or hepatic diseases * severe ischemic heart disease * severe pulmonary disease * history of bariatric surgery * alcohol abuse (\> 50 grams/day) * illicit drug abuse (other than marijuana based on self-report) * combustible tobacco use * uncontrolled diabetes based on HbA1c\>9.0% * eating disorder * cancer treatment within the past 12 months * history of CRC * genetic predisposition to CRC (e.g., Lynch syndrome) * weight \> 450 lbs. (weight limitation of the DXA scanner) * currently adhering to a MedDiet based on a diet screener * self-reported WL \> 3% in the past 12 months * currently on a WL diet or actively involved in a formal WL program (e.g., Weight Watchers) * food allergies that would interfere with adopting a MedDiet * antibiotic use in the past 3 months * night-shift work * regular use (i.e., ≥ 3 times per week) of prebiotics/probiotics/synbiotics, dietary fiber supplements, or laxatives, * Gait disorder * currently pregnant * active Covid-19 infection within 6 weeks of recruitment/data collection.
Conditions4
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NCT04753359