 This study is a single site, Phase I, masked, randomized study to evaluate the safety and tolerability of twice daily dosing of LGG Lactobacillus GG ATCC 53103 in normal healthy adult volunteers. Study drug capsules 1x1010 LGGcapsule or placebo will be taken by mouth twice a day with cows milk or soy milk on an outpatient basis. Volunteers will have study visits at baseline, 1 month, 3 months, 6 months, 7 months, and 12 months where they will be asked about any medical problems that have come up since the last study visit, have vital signs taken, review current medication use, and review any signs of potential adverse events. Blood and urine samples will also be collected at these visits, as well as throat and stool samples. 