Fiber Effectively Educates & Directs the Microbiome Study

Upon enrollment, healthy adults will enter a 15-day lead-in period during which they will refrain from consuming specific foods and collect a baseline stool sample. The intervention period will be on days 16-33 during which participants will consume study provided high-arabinose foods. The follow-up period will be on days 34-49 during which participants will no longer eat the study foods and will refrain from consuming specific foods. The total duration of the study will be approximately 7 weeks. Stool samples will be collected on 3 occasions and participants will be asked to complete questionnaires, daily stool logs, dietary intake reports, and 24-hour dietary recalls throughout the course of the study.

Inclusion criteria

• Healthy adults;
• Age 18-50 years of age;
• BMI between 18.5 and 34.9 kg/m2;
• Lives within a 40-mile radius from the UC Davis campus in Davis or UCDMC in - Sacramento, CA or study personnel residences;
• Consumes food at least three times (meals/snacks) per day;
• Non-alcohol consumers or those who consume alcohol in moderation defined as having up to 1 drink per day for women and up to 2 drinks per day for men;
• Normal stool frequency defined as 3 times per week to 3 times per day;
• Has been weight-stable (has not lost or gained 10% of body weight) within the past 3 months;
• Speaks, writes, and understands English to complete study activities;
• Lives in a household whereby stool samples and study food can be reliably stored without interference from other household members (i.e., excluding individuals who reside in fraternity, sorority houses whereby freezer access is open to all members);
• Lives in a household with access to Wi-Fi and/or cellular access to enable completion of electronic questionnaires (i.e., PIP forms) on their own personal computer, cell phone, or electronic device;
• Willingness to consume study-provided foods for 18 consecutive days;
• Willingness to fill out a short online survey about the amount of each study food they consumed during the two-week intervention;
• Willingness to collect stool samples on three separate days and store them in their home freezer before they (or study personnel) transport them to UC Davis;
• Willingness to complete online weekly health questionnaires;
• Willingness to complete two online enrollment questionnaires about diet and health history;
• Willingness to complete Daily Stool Logs (7 consecutive days) at 3 separate times during the study period;
• Willingness to complete two 24-hour dietary recalls by video call with study personnel (prior to each of the 3 stool collections required for the study);
• Willingness to have four in-person visits (at their homes or on campus);
• Willingness to use their personal computer, cell phone, or electronic device to meet virtually with study personnel;
• Willingness to refrain from consuming fermented foods, or foods with probiotics or probiotic supplements and other foods listed on the study materials (confounding variables of the intestinal microbiome) during the study period;
• Willingness to refrain from consuming iron containing dietary supplements (multi-vitamin is permitted) and fiber supplements during the study period;
• Willingness to refrain from changing (starting a new or discontinuing a current) routine vitamin/mineral supplement regimen during the study period;
• Willingness to refrain from changing (starting a new or discontinuing a current) routine medication regimen during the study period;
• Willingness to refrain from consuming laxatives during the study period;
• Willingness to refrain from enrolling in other experimental trials during the study period;
• Willingness to avoid binge alcohol drinking during the study period defined by the CDC as: drinking 5 or more drinks on a single occasion for men or 4 or more drinks on a single occasion for women, generally within about 2 hours;
• Willingness to refrain from using tobacco (smoking or chewing or using E-cigarettes) or smoking, vaping or consuming cannabis or use of other illicit drugs during the study period;
• Willingness to refrain from having any non-emergency, elective surgeries including dental surgery or invasive medical procedures during the study period;
• Willingness to take a study-provided urine pregnancy test if female;
• Mid- to high-income families and low-income families based on household income or eligibility for the California Supplemental Nutrition Assistance Program (SNAP) or Special Supplemental Nutrition Program for Women, Infants, and Children (WIC).

Exclusion criteria

• Currently pregnant or plans to become pregnant several weeks prior to enrollment and during the study period;
• Currently lactating;
• Use of restrictive diets such as caloric restriction, intermittent fasting, keto-diet, gluten-free, grain-free, dairy-free within the past 6 months;
• Known or suspected allergy (childhood allergies pre-puberty is acceptable) to milk, egg, wheat, legumes including soybeans; peanuts, tree nuts and seeds, and any fruits and vegetables used in the study;
• Known or suspected sensitivity or intolerances to any foods and ingredients used in the study (e.g., lactose intolerance, etc.) such as milk, egg, wheat, legumes including soybeans, peanuts, tree nuts and seeds and any fruits and vegetables used in the study;
• Aversions to or avoidance in eating foods and ingredients used in the study (legumes/beans, fruits, vegetables, peanuts, tree nuts and seeds);
• History of any type of eating disorder (anorexia nervosa, bulimia, etc.);
• History of any of the following: Positive infection of HIV, AIDS, hepatitis B or C; GI tract abnormalities; Any type of bariatric surgery or other gastric surgery involving the removal of sections of the GI tract (appendectomy or hernia repairs are acceptable), or gall-bladder removal; GI-related conditions such as malabsorption disease, celiac disease, Crohn's disease, colitis, inflammatory bowel disease (IBD), irritable bowel syndrome (IBS); Cancer (history of skin cancer that is in remission is acceptable), heart, liver, lung, endocrine, or kidney diseases; Type 1 or 2 diabetes mellitus; Cushing syndrome; Primary immune deficiency or autoimmune diseases; Uncontrolled hyper or hypothyroidism; uncontrolled hypertension (controlled with medication is acceptable);
• History of stomach ulcers or diagnosis with H. pylori infection; chronic gastritis within the past 12 months;
• Gastroenteritis (caused by stomach flu or food poisoning caused by virus or bacteria) within the past 4 weeks;
• Have any medical or nutritional conditions that require iron supplementation;
• Intake of iron supplements (stand-alone doses that are not part of a multi-vitamin) within the past 4 weeks;
• Positive test for COVID-19 based on a rapid test or PCR within the past 2 weeks;
• Use of oral, intramuscular or IV antibiotics or sulfonamides within the past 3 months;
• Vaccinations received less than the past 2 weeks (may enroll two weeks following treatment with vaccinations);
• Use of biologics that suppress the immune system, i.e., Lantus, Remicade, Rituxan, Humira, Herceptin, Avastin, Lucentis, Enbrel, for 2 weeks or longer or within the past 4 weeks;
• Use of injectable (or pill) weight loss medications or biologics such as Ozempic, Wegovy, Rybelsus, etc. within the past 4 weeks;
• Surgery or an invasive medical procedure within the past 3 months;
• Plan to have any elective surgeries including dental surgery or invasive medical procedures during the study period;
• Illness (flu, cold, etc.) within the past 2 weeks (free of all illness symptoms within the past 2 weeks);
• Routine use of medications found to alter the gut microbiome such as: Tylenol, aspirin, naproxen sodium or ibuprofen (except for acute uses with sickness or injury), anticholinergic inhalers, opioids, proton pump inhibitors, gastric acid suppressors (e.g., pepcid), metformin, statins, steroids (oral-inhaler is acceptable), 6-Marcaptopurine, Azathioprine or any other immunosuppressants on a daily basis within the past 6 months;
• Plans to start or plans to have changes made to a dose (including starting or adjusting an existing dose) of selective serotonin reuptake inhibitors (SSRIs), or antipsychotics during the study period;
• Plans to start or plans to have changes made to a dietary supplement regimen (vitamins/minerals/herbal supplements) or a medication regimen during the study period;
• Persistent (lasts longer than 2 weeks and less than 4 weeks) or chronic (lasts at least 4 weeks) diarrhea (loose, watery stools three or more times a day) within the past 6 months;
• Chronic constipation (fewer than 3 stools per week, stool form that is mostly hard or lumpy and difficult stool passage (need to strain or incomplete evacuation) with the past 3 months;
• Use of probiotic supplements within the past 8 weeks;
• Individuals who use laxatives more than once per week;
• Individuals who use fiber supplements more than once per week;
• Current tobacco (smoking or chewing) or E-cigarette users or individuals who quit using less than one year before enrolling in the study;
• Frequent cannabis use (eating, smoking, or vaping) defined as greater than 4 times per week and greater than 14 times per month;
• Use of illicit drugs (cocaine, crack, heroine, unprescribed fentanyl etc.);
• Excessive alcohol drinkers: For men, heavy drinking is typically defined as consuming 15 drinks or more per week. For women, heavy drinking is typically defined as consuming 8 drinks or more per week (https://www.cdc.gov/alcohol/faqs.htm);
• Individuals who currently live or plan to live within the same household during the study period or who are in intimate relationships with current or past study participants (to avoid horizontal transfer of the gut microbiome),
• Individuals who plan to travel during the stool collections and intervention phase of the study duration.