Dietary fiber has been shown to have beneficial effects on human health through its impact on microbes present in the gut. However, these effects can vary between individuals, and everyone may not reap the same health benefits by eating the same sources of fiber. Factors predicting how an individual's gut microbes as well as the beneficial metabolites produced by these microbes change in response to different sources of fiber would be helpful in developing precision nutrition approaches that maximize the benefits of dietary fiber. The objective of this study is to evaluate candidate predictors of gut microbiota response to fiber sources from either whole grains or fruits and vegetables.

Inclusion Criteria:

• Age is between 21-50 years
• BMI is between 25-30. You can check your BMI here: https://www.cdc.gov/bmi/adult-calculator/index.html
• Must be able to have height, weight, waist, and hip circumference, and body composition measured during the study
• Must be able to provide saliva samples.
• Must be able to provide a phone number and email address at which the study investigators can contact for study-related matters.
• Must be able to increase dietary fiber intake to the recommended level following the instructions on the USDA MyPlate website: https://www.myplate.gov/myplate-plan
• Must be able to provide food records of everything consumed (food, beverage, and supplements) on one weekday and one weekend day (example Tuesday, Saturday) every week during the study. This will be done using an online survey.
• Must be able to provide 10 stool samples over 11 weeks of the study duration. 18) Must have stable weight (within ±3% of usual body weight) for the last two months.
• Must be able to to take an online survey to assess recent dietary fiber intake to determine eligibility.

Exclusion Criteria:

• Electronic medical implant, for example, a pacemaker.

• An existing, UNTREATED, thyroid condition.

• Use of systemic antibiotics (intravenous injection, intramuscular, or oral) within the last 4 months.

• An acute disease at the time of enrollment (Acute disease is defined as the presence of a moderate or severe illness with or without fever).

• A chronic, clinically significant (unresolved, requiring ongoing medical management or medication) pulmonary, cardiovascular, gastrointestinal, hepatic, or renal functional abnormality.

• Any suspected state of immunosuppression or immunodeficiency including HIV.

• A history of active UNTREATED gastrointestinal disorders or diseases including

  1. Inflammatory bowel disease (IBD)
  2. Ulcerative colitis (mild-moderate-severe)
  3. Crohn's or celiac disease
  4. Indeterminate colitis
  5. Irritable bowel syndrome (IBS) (moderate-severe)
  6. Persistent, infectious gastroenteritis, colitis or gastritis
  7. Persistent or chronic diarrhea of unknown etiology
  8. Clostridium difficile infection (recurrent)
  9. Chronic constipation

• Previously had bariatric surgery.

• An unstable dietary history as defined by major changes in diet during the previous month. For example, elimination or significantly increased intake of a major food group in the diet.

• Recent history of chronic alcohol consumption defined as more than 5 drinks (or servings) of alcohol per day.

• Female participants: pregnant/lactating.

We will NEVER share de-identified data about the participants. Our previous publications show aggregated data results. This study is identical to our previous in design, sample types, and data being collected. We shared the de-identified 16S rRNA sequence data of the participants in a public database as requested by the journals. When requested by a journal, we have shared eligibility criteria. Some journals may require us to share our statistical code.