Study Details

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  • Who is conducting this study?
  • The Gut Microbiome and Carbohydrate Function of Healthy Adults (GENIUS) Study is led by Dr. Jennifer Smilowitz, PhD, at the UC Davis Foods for Health Institute along with Dr. Carlito Lebrilla, PhD, of the Department of Chemistry, Dr. David Mills, PhD, of the Department of Food Science and Technology, and Dr. Danielle Lemay, PhD, of the USDA, ARS, WHNRC at UC Davis. This study has been reviewed and approved by the UC Davis Institutional Review Board.
  • What is the purpose of this study?
  • The purpose of this 4-week study is to test how different types of fiber found in food influences the growth of healthy gut microbes found in stool samples from healthy adults.

  • Who can participate?
  • Healthy adults who are 18-65 years old;

    Individuals with a body mass index (BMI) between 18.5-29.9;

    Individuals who live within a 40-mile radius from the UC Davis campus in Davis;

    Individuals who eat about 5 fruits/vegetables per day;

    Individuals who have regular bowel movements, defined as 3 times per week to 3 times per day;

    Individuals who consume alcohol in moderation or consume no alcohol;

    Individuals who are willing to avoid binge drinking during the study period;

    Individuals who are willing to refrain from consuming fermented foods or products containing probiotics during the study period.

  • Who is NOT eligible to participate?
  • Individuals who are pregnant;

    Individuals with any gastrointestinal disorders;

    Individuals who currently have food allergies or asthma;

    Individuals who have consumed products containing probiotics, such as kombucha, kefir, some brands of yogurt or probiotic supplements in the past 8 weeks;

    Individuals who have used antibiotics within the past 6 months;

    Individuals who currently smoke or chew tobacco or use E-cigarettes, or used within the past year;

    Individuals who frequently smoke, eat, or vape marijuana or use illicit drugs;

    Individuals who use alcohol excessively.

  • What is expected of me during the study?
  • This study lasts up to 4 weeks or until you collect stool samples that total 300 grams (about the size of 1 large banana), whichever comes first. During the study you will be asked to do the following: collect 300 grams of stool; complete one 24-hour dietary recall with each stool sample collection; and fill out daily logs regarding your gut health and dietary intake. Study personnel will instruct you on how to collect samples and complete questionnaires. You will be asked to store your collected samples inside of a sealable freezer box in your home freezer until a scheduled pick up time within 48 hours. You will also have the option to drop-off your collected stool samples at the UC Davis campus in Davis.

  • Will I be compensated for participation?
  • Participants will receive up to a $75 in Target gift to complete the study activities.