Safety, Tolerability and Host Response to Lactobacillus Johnsonii

Healthy adult volunteers from 18-50 years of age will be recruited through the University of Florida and randomly distributed into two groups. This study is divided into 3 phases: baseline, intervention (study treatment) and washout. Participants will receive either the probiotic or placebo during the intervention phases. During the baseline phase, blood and fecal samples will be collected about 1 week before intervention initiation. On the day of a scheduled blood draw, the participant will need to arrive fasted overnight, and a light breakfast will be provided after blood draw. Starting on day 1 of the intervention phase, a second baseline blood sample will be collected and the participant will begin the study intervention (probiotic or placebo). Participants will consume 1 capsule (probiotic or placebo) daily for 8 weeks, and blood and stool samples will be collected and processed (on or around weeks 2, 4 and 8 of the intervention phase). A Fisher Scientific commode specimen collection system will be provided for stool collections. The stool collection kit may be taken home (participants will be asked to drop off the stool within 4 hours of defecation) for fecal sample collection or may use the restroom in the clinical lab at the Food Science and Human Nutrition Building in which kits will be provided for use. In the wash-out phase, participants will not consume the capsule (either the probiotic or placebo), but will provide blood and stool samples (on or around week 12). Throughout the study, participants will provide a total of 5 stool samples and 6 blood samples. Participants will be asked to complete daily and weekly questionnaires throughout all phases of the study, which will ask about quality of life (physical functioning, mental functioning, level of sleep, etc.), gastrointestinal function, and dietary intake. These assessments will be self-reported via online questionnaires. In the event that internet access is not available for a portion of the study, paper copies of the questionnaires may be provided.