Pill that samples your gut could reveal diet secrets

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

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.