This study evaluates the effect of a dietary supplement to improve gut health. The participants will take one of six dietary treatments for three weeks, and the gut bacteria and the gut intestinal barrier will be assessed to determine if these dietary treatments beneficially change these markers of gut health.

In this study, we intend to test the ecological and therapeutic functionality of a synbiotic combination of a Bifidobacterium adolescentis strain and the prebiotic galactooligosaccharide (GOS) in a human clinical trial. The synbiotic combination was selected based on a novel in vivo selection; specifically, the strain (BD1) is an human autochthonous gut organism that was enriched in an individual by GOS. Our experiments will test the efficacy of this synbiotic compared to a conventional synbiotic. We hypothesize this rationally selected synbiotic will improve intestinal barrier function in obese adult subjects, thereby preventing endotoxemia and metabolic inflammation, physiologically relevant functions that are increased in obese individuals. Our objectives are to: (1) compare the ability of the test and control synbiotic preparations to alter the gut microbiota in obese individuals; (2) test if GOS supports colonization and metabolic activity of test and control strains in the human gut; (3) compare the ability of the two synbiotic preparations to improve intestinal permeability and endotoxemia in obese subjects; and (4) assess associations between the gut microbiota and the test strain with biomarkers for translocation and endotoxemia.

Inclusion Criteria:

• 18-65 yrs, obese (30 kg/m2 and greater)

Exclusion Criteria:

• (1) prior intestinal resection, (2) patient history of GI diseases except for hiatal hernia, GERD, hemorrhoids, (3) severe renal disease defined by creatinine more than twice normal, (4) markedly abnormal liver function defined by ALT/AST over 4 times normal levels or elevated bilirubin (5) antibiotic use within the last 12 weeks prior to enrollment, (6) lean or overweight (BMI < 30 kg/m2), (7) intolerant to aspirin, (8) regular use of aspirin, (9) excessive alcohol intake (>2 drinks for men, 1 drink for women daily), (10) presence of uncontrolled chronic metabolic disease (cardiovascular disease, insulin requiring diabetes or uncontrolled diabetes, cancer, etc, (11) a plan to have a major change in dietary habit during the following 6 months, (12) consumption of probiotics, prebiotics or synbiotics without an appropriate 4 week washout period, (13) lactose intolerance or malabsorption; (14) subjects younger than 18 or older than 65, (15) unwillingness to consent to the study.