See also doi:10.1371/journal.pone.0113456.t001 <th>Inclusion Criteria</th> <th>Exclusion Criteria</th> 1. Adult male and female age 65--80 years 1. Resident of a nursing home or rehabilitation center 2. Has a primary care physician 2. Hospitalization, major surgery or endoscopy within the last 3 months or scheduled hospital admission within 3 months of enrollment 3. In the past two years: 3. Consumption of any probiotic or yogurt that has the "live and active cultures" seal during the 28 days before the baseline visit and unwillingness to forgo these products during the 56 day study period a. Is community-dwelling 4. Received oral or parenteral antibiotics during the 28 days before the baseline visit b. Has had a routine physical examination 5. Current or planned oral or parenteral immunosuppressive therapy, chemotherapy or radiotherapy c. Has no new chronic conditions diagnosed 6. Allergy to probiotics, Lactobacillus, all antibiotics that could be used to treat Lactobacillus infection, microcrystaline cellulose or gelatin 4. Has received and is up to date on the following: 7. Diarrhea, constipation or vomiting during the 28 days before the baseline visit a. Pneumococcal vaccination 8. Serious gastrointestinal illness including chronic liver disease, gastrointestinal surgery, cancer, inflammatory bowel disease, pancreatitis or motility disorder in the last 2 years b. Mammography (women only) 9. History of drug or alcohol abuse in the previous 12 months c. Screening colonoscopy 10. History of structural heart disease, endocarditis, valve replacement, Stage IV congestive heart failure, peripheral vascular disease, stroke, chronic obstructive pulmonary disease, asthma, collagen, vascular or autoimmune disease, end stage renal disease, diabetes, thyroid disease or active tuberculosis 5. Willing and able to comply with the protocol and participate for the planned duration of the study 11. Presence of an indwelling catheter, implanted hardware/prosthetic device or feeding tube 6. Completes the informed consent process 12. Any Grade 2 or higher abnormal vital sign or physical examination finding (FDA Toxicity Grading Scale) 13. Positive HIV antibody, hepatitis B surface antigen or hepatitis C antibody 14. Positive urine toxicology or positive breathalyzer 15. Any Grade 2 or higher abnormal screening laboratory test (FDA Toxicity Grading Scale) 16. Enrolled in another study