Gut Mini-Pill Study

Inclusion Criteria:

* Men and postmenopausal women
* Age \>50 to \<75 years
* BMI \>20 to \<35 kg/m2
* Normotensive with or without medication
* Normal gastrointestinal function with regular bowel movements at least once every other day
* Normal kidney and liver function
* Willingness to swallow the mini-pills
* Willingness to collect and return multiple stool samples
* Adequate refrigerator and freezer space to store study entrées
* Intent to remain in the greater Boston area during the intervention periods

Exclusion Criteria:

* Individuals self-reporting adhering to any type of vegetarian diet
* Lack of willingness to restrict fish intake to less than once per week during the dietary intervention phases
* Allergy/intolerance/religious reasons to avoid study foods or food ingredients, including known hypersensitivity to Blue 1 food coloring and wheat gluten.
* Regular use of prebiotics or probiotics within the past 3 months
* Regular use of laxatives or fiber supplements
* Chronic constipation
* Chronic use of antibiotics (except topical)
* Regular use of stomach acid lowering and weight loss medications such as GLP-1 agonists
* Use of dental prophylaxis
* Planned colonoscopy 2 months prior to or during the study period
* Gastroparesis
* Swallowing disorder, or inability or difficulty taking pills
* Malabsorptive and inflammatory bowel disease, diverticulosis, and history of diverticulitis, gastric/ esophageal/intestinal surgery, including lap banding or bariatric surgery.
* History of bowel obstruction, pancreas and liver disorders.
* Any form of active substance abuse or dependence (including drug or alcohol abuse). This information will be stored in REDCAP in a subsection that has no identifiers.
* Established major chronic diseases such as cardiovascular disease, diabetes, active cancer within the last 5 years, or any significant medical condition at the study MD's discretion
* A clinical condition that, in the judgment of the study MD or principal investigator, could potentially pose a health risk to the subject while involved in the study.
* Unwillingness to adhere to study protocol
* Intent to increase or decrease body weight during the study period
* No Social Security number (for payment and IRS forms).
* Individuals who directly report to any member of the research team.