Study #3040 The MERIDIAN Study

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For more information about enrolling in this study, please call Volunteer Services:

Purpose of this study
The purpose of this study is to determine whether taking two different forms of a probiotic, known as Bifidobacterium animalis subsp. Lactis (or B. Lactis for short) changes the bacteria balance in your intestines, as compared to a placebo. These potential changes may have effects on gut health, obesity risk and chronic inflammation; in addition, these changes may have an effect on general well-being such as sleep and physical activity patterns. Probiotics are known as “good” bacteria because they help keep your gut healthy by helping with your digestion. Probiotics can be found in supplements and some foods like yogurt, sauerkraut, pickles and miso soup.

Target Population
Individuals, ages 18 years and older

Major Exclusions

  • Vegetarians or vegans
  • Currently pregnant, planning to become pregnant or breastfeeding
  • Having irregular bowel movements (<1 time per day)
  • Diabetes or taking diabetes medications (except for metformin for pre-diabetes)
  • Diagnosis of kidney, liver, heart, gallbladder or gastrointestinal diseases
  • If you consume 2 or more Alcoholic drinks per day
  • If you smoke tobacco or marijuana in the last 6 months, or unwilling to stop using marijuana products (incl. CBD oil or edibles) during the study.
  • If you regularly use any probiotic or prebiotic supplements; however, subjects who are willing to refrain from the use of probiotics supplements for 30 days prior to their enrollment and throughout the entire study may be considered eligible.

Length of Study
5 months


Number of visits
1 screening visit, one enrollment visit; three cycles of three visits each with a 28 days reset period in-between cycles. Each study visit (except for the enrollment visit) will involve the collection of blood, urine, and stool samples, as well as medical information (i.e. waist circumference, weight, vitals, etc.), filling out questionnaires, and completing dietary recalls.

Study diet
Subjects will be asked not to intentionally change their level of activity (research, movement, etc.), diet (except for avoiding pre and probiotics foods and supplements (other than those given by the study team)), or their weight for the duration of the study. Subjects will be required to take a probiotic supplement or placebo, up to 3 capsules a day (3 capsules per day for approximately the first 3 days of each cycle, then only one capsule per day for the remaining 25 days in each cycle).

$25 for screening visit, and up to $1250 for participants who qualify and complete the entire study

Can I work?
Yes, but if subjects employed by Tufts University qualify to participate in the study, they cannot participate as subjects during hours in which they are being compensated by Tufts University for their regular work. This includes the use of vacation, personal days and sick time.


Length of study
Total length of the study including resident stays and nonresident visits.
This does not mean you will be testing the entire time.
The length of time volunteers are required to stay overnight at the HNRCA. Residents have their own private room, bathroom, television, VCR, and phone during their stay.
The amount of reimbursement for travel and inconvenience.
Number of visits
Total number of nonresident visits.
Study diet
Indicates meals which will be provided by the HNRCA
Can I work?
Indicates if you will be able to work and if so, when.

For more information about this study, please call Volunteer Services at 1-800-738-7555.

We appreciate your interest in our program and we hope to work with you in the future.

Thank you,
The Recruitment Office
Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University