Probiotic Supplementation on Weight Loss

The investigators are interested in seeing how a probiotic, which is a dietary supplement
containing large amounts of 'good' bacteria, can influence the make-up of the gut bacterial
population and what effect it has on weight loss and loss of fat. Before undergoing weight
loss surgery (sleeve gastrectomy or roux-en-y gastric bypass), study participants will be
asked to provide a stool sample to assess the make-up of their gut bacterial population. They
will also undergo a limited CT scan of the abdomen and DEXA (Xray) to help assess the amount
of fat present inside the body.

After undergoing weight loss surgery (sleeve gastrectomy or roux-en-y gastric bypass), study
participants will be given either a probiotic supplement or dummy pill (placebo) for 3
months, in addition to all usual care that occurs after surgery. The CT scan, DEXA scan and
stool sample will be repeated at the end of the 3 month period and analyzed for changes.

Inclusion Criteria:

1. All subjects who are > 18 and < 65 years of age recruited from the Mayo Clinic
bariatric surgery clinic

2. Will also meet one of the National Institute of Health's criteria for bariatric
surgery, i.e. body mass index (BMI) > 40 kg/m2 or BMI > 35 kg/m2 with significant
weight-related comorbidities.

3. Patients will be eligible if they are not on chronic antibiotic therapy and without
active systemic illness.

Exclusion Criteria:

1. Patients with type 1 or 2 diabetes will be excluded due to the known pre-existing
changes in the gut microbiome in this population. All patients will not have had
exposure to probiotics, prebiotics or antibiotics in the preceding 4 weeks.

2. Patients with allergy to antibiotics precluding the use of standard peri-operative
antibiotics (cefazolin and metronidazole) will be excluded.