This trial has been completed.

Condition healthy
Treatments l. johnsonii n6.2, placebo
Sponsor University of Florida
Collaborator Juvenile Diabetes Research Foundation
Start date August 2015
End date December 2016
Trial size 42 participants
Trial identifier NCT02349360, 201400370


The purpose of this research study is to determine the effects of the probiotic, Lactobacillus johnsonii N6.2, on safety, gastrointestinal function, wellness, fecal bacteria and blood biomarkers in healthy individuals.

United States No locations recruiting
Other countries No locations recruiting

Study Design

Allocation randomized
Endpoint classification safety study
Intervention model parallel assignment
Masking double blind (subject, investigator)
(Active Comparator)
L. johnsonii N6.2 10^10 CFU in capsule form administered for 8 weeks (n=15)
l. johnsonii n6.2 Lactobacillus
L. johnsonii N6.2 10^10 CFU in capsule form administered for 8 weeks (n=15)
(Placebo Comparator)
Encapsulated starch placebo administered for 8 weeks (n=15)
Encapsulated starch placebo administered for 8 weeks (n=15)

Primary Outcomes

Number of participants reporting Adverse Events
time frame: 13 weeks

Secondary Outcomes

Composite measure of Blood chemistry profiles
time frame: 13 weeks
Composite measure of General well-being, gastrointestinal function, and mood questionnaires
time frame: 13 weeks
Transit survival of L. johnsonii N6.2
time frame: 13 weeks
Composite measure of Total immunoglobulin and cytokine measurements
time frame: 13 weeks
Circulating leukocyte subpopulations
time frame: 13 weeks
IDO-mediated metabolic intermediates (composite)
time frame: 13 weeks

Eligibility Criteria

Male or female participants from 18 years up to 50 years old.

Inclusion Criteria: - To participate in the study individuals must - be 18-50 years old. - be willing to complete multiple questionnaires via computer. - be willing to take the probiotic or placebo capsule daily for 8 weeks. - be willing to provide 1 stool during weeks 0, 2, 4, 8 and 12 of the study. - be willing to provide blood samples at weeks -1, 0, 2, 4, 8 and 12 of the study. - have daily access to a computer with internet access for the entire 13-wk study. - be willing to provide a social security number Exclusion Criteria: - To participate in the study individuals must NOT - currently take medications for constipation, diarrhea or psychological disorders (depression, anxiety, insomnia etc.). - have taken antibiotics within the past four weeks prior to randomization. - currently take probiotic supplements and do not want to discontinue a minimum of two weeks prior to the study - have had or are currently being treated for any diseases or illnesses such as gastrointestinal disease (gastric ulcers, Crohn's, ulcerative colitis, etc.), chronic disease like diabetes or kidney disease, immune-compromising diseases or conditions (HIV, AIDS, hepatitis, cancer, transplant patient etc.) - currently receive medical treatment for stress induced symptoms/disorders - be a current smoker

Additional Information

Official title Safety, Tolerability and Host Response to Lactobacillus Johnsonii
Principal investigator Wendy J Dahl, PhD
Description Healthy adult volunteers (30 individuals) 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.
Trial information was received from ClinicalTrials.gov and was last updated in December 2016.
Information provided to ClinicalTrials.gov by University of Florida.