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.
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
- 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
- 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