Prebiotic Effects of California Grapes on Gut Health and Cardiometabolic Health in Overweight Men and Women

Inclusion Criteria: * post-menopausal women (cessation of menstruation for minimum two years) * overweight and obese (BMI between 25-35 kg/m2) * stable treatment for type 2 diabetes or metabolic syndrome * ability to understand the intervention concept and written consent to participate * willingness to accept randomization, undergo testing and intervention procedures, and deliver stool and blood samples Exclusion Criteria: * menopausal hormone replacement therapy started within less than 6 months * antibiotics, prebiotics within last 3 months * antidiabetic treatment involving insulin (for type 1 diabetes) * vegetarian/vegan and not able to follow modified diet * any serious medical condition including but not limited to coronary artery disease, uncontrolled hypertension, stroke, congestive heart failure, insulin-dependent diabetes, liver disease, active cancer and anemia * psychiatric disease that interferes with the understanding and implementation of the intervention * history of eating disorders such as bulimia nervosa, anorexia nervosa, severe binge eating disorder in the last 5 years * history of substance abuse or alcohol abuse * involvement in a weight loss intervention program (including anti-obesity medication) within last 3 months or have had bariatric surgery * current smokers (within last 180 days) * use of dietary supplements containing polyphenols in the past 1 month * strenuous exercise greater than 10 hours per week