Gut Microbial Metabolites of Apple Polyphenols

This is a randomized, cross-over controlled feeding trial. Thirty healthy adult volunteers will be selected to participate on the basis of urinary screening results measuring a gut bacterial metabolite that is produced following consumption of a soy food: 15 O-desmethylangolensin (ODMA) producers and 15 age and gender-matched ODMA non-producers will be included. Participants will be assigned to consume two diets in random order: an apple catechin diet that provides a controlled amount of catechins in apple juice, and a nutritionally-matched low catechin diet. Both diet phases will last 3 days, with a 10 day washout period in between the two diet phases.

Inclusion criteria

• Completion of informed consent.
• Stated willingness to comply with all study procedures and availability for the duration of the study.
• Any gender identification, aged 18 - 45.
• BMI 18.5 - 40 kg/m^2
• Ability to consume the intervention foods and beverages and be willing to adhere to the dietary regimen.
• Agreement to provide urine and fecal samples according to the study protocol.
• Agreement to adhere to avoid high catechin foods (tea, chocolate) for 4 weeks.
• Able to come to the study location for 8 visits according to the study schedule.
• As assessed through an initial urine screening phase, a person is eligible either on the basis of (1) the presence of a urinary marker for soy isoflavone metabolism (ODMA), or (2) as a control matched for age and gender.

Exclusion criteria

• Current, regular use of antacids or acid reducers.
• Systemic antibiotic use within the past month prior to the urinary screening until completion of the dietary intervention.
• Pregnancy or lactation, within 3 months post-partum (regardless of breastfeeding) at screening or planning to become pregnant during the study duration.
• Known allergic reactions to components of the foods or beverages of the study diet (soy, wheat, dairy, peanut, tree nuts, apples, eggs) or any history of anaphylactic food allergy.
• Current diagnosis of renal, hepatic, or gastrointestinal conditions.
• History of stroke.
• Underweight (BMI <18.5 kg/m^2) or severe obesity (BMI >40 kg/m^2).
• Under 18 years or above 45 years of age.
• Unwilling or unable to participate in the controlled dietary intervention or provide urine or fecal samples.
• Has a pacemaker, implanted defibrillator, or other implanted electronic device.
• Change of body weight >10% between screening and dietary intervention.