Evaluating the Effects of a Synbiotic Versus Probiotic or Placebo on Gut Microbiota and Cardiometabolic Health: A Randomized Double-Blind Placebo Controlled Trial

Specific Aim 1. Explore the changes in the gut microbiome using 16s rRNA sequencing to determine total bacterial counts, microbial diversity (alpha- and beta-diversity), short chain fatty acid (SCFA) concentration, circulating inflammatory biomarkers and mucosal immunity as a result of synbiotic vs. probiotic vs. placebo control.

Specific Aim 2. Document the functional changes in cardiometabolic health-related parameters; specifically, heart rate, heart rate variability (HRV), blood pressure (central and peripheral), vascular stiffness (augmentation index, AIx, and pulse wave velocity, PWV), body weight and composition, blood glucose and lipids as a result of synbiotic vs. probiotic vs. placebo control.

Specific Aim 3. Characterize the impact of synbiotic vs. probiotic vs. placebo control on perceptions of fullness/hunger, self-reported gastrointestinal health (questionnaire), and mood states.

Hypothesis: We hypothesize that the synbiotic will result in greater changes in total gut bacterial count, microbial diversity, SCFA, while reducing circulating markers of inflammation and increasing determinants of mucosal immunity. Second, the synbiotic will result in greater enhancement of cardiometabolic health over the probiotic or placebo control. Third, the synbiotic will maintain or improve perceptual indicators of fullness/hunger, gastrointestinal health, and mood states over probiotic alone or placebo control.

Inclusion criteria

• To be included participants must be healthy, weight stable (± 4.4 lb for > 6 months prior), and 18 to 60 years of age. Participants will be expected to be relatively healthy without uncontrolled chronic disease (e.g. cardiovascular, metabolic, or pulmonary) and 1 or fewer positive risk factors for cardiovascular disease (e.g. high blood pressure, high cholesterol, etc.) as described by the American College of Sports Medicine/American Heart Association Criteria and presented in the table 1 below. Per College policy, participants who are visitors are required to be fully vaccinated against COVID-19, including a booster, and participants who are faculty, staff or students are required to be fully vaccinated against COVID-19 and receive a booster by January 24, 2022 or within 30 days of becoming eligible, unless a medical or religious exemption has been granted. Participants will be screened for eligibility by health history form in person baseline measurements are made (Figure 1). To ensure greater inclusion, ecological validity and representation, women will be included in this study; however, we will not control for menstrual cycle phase, but will document for possible statistical consideration.

Exclusion criteria

• Given the focus of the study those who are currently, or have recently used (<3 months), oral antibiotics or have diagnosed irritable bowel syndrome or gut/bowel maladies (short bowel syndrome, etc.) will be excluded. Subjects who present with 2 or more CVD risk factors (table above) or have uncontrolled/overt cardiovascular, pulmonary, or metabolic disease (Diabetes Mellitus), or recent blood donation (<8 weeks) will be excluded. Those who have cancer or are being treated for cancer will also be excluded. Women who are currently pregnant, breastfeeding, attempting to conceive, or amenorrheic (not associated with menopause or use of contraceptive medications) will also be excluded from the study. Anyone who is being treated for hypothyroid with levothyroxine will be excluded as one of the supplement ingredients, chromium polynicotinate, may interfere with this medication . Anyone with severe illness or compromised or suppressed immune system (e.g. taking immune suppressants, chronic viral infection or treatment) will be excluded. Anyone recently diagnosed (<1yr) with an eating disorder or food allergies will also be excluded.