Prebiotic Inulin for Late-Reproductive Individuals

This proposal presents a proof-of-concept study of the Prebiotic Inulin for Late Reproductive Individuals (PILI) intervention, a prebiotic fiber supplementation among women with perimenopause and overweight or obesity.

More specifically, the PILI intervention integrates multi-omics, physiological, and cardiometabolic assessments to examine the effects of inulin supplementation on overall health during the menopausal transition. Outcomes include changes in the gut and vaginal microbiome and their functional activity, gut-derived metabolites, vascular health, metabolic flexibility, skeletal muscle oxidative capacity, body composition, physical activity, sleep, dietary intake, and other cardiometabolic health markers. The target age range for this intervention is 40-55 years, reflecting the perimenopausal stage of life. Participants must also have overweight or obesity.

Participants will be randomly assigned to receive both the study intervention, inulin, and placebo, in a blind crossover design. Each participant will complete two intervention periods, separated by a washout period, allowing every participant to serve as her own control. Throughout the study, participants will consume the assigned supplement daily and attend scheduled in-person research visits before and after each intervention period.

At these visits, the research team will collect biological samples, including blood, stool, and vaginal swabs, and perform a comprehensive series of clinical assessments. These assessments include body composition, vascular health, metabolic flexibility, skeletal muscle oxidative capacity using near-infrared spectroscopy, physical function, and cardiometabolic testing. Participants will also complete questionnaires related to dietary intake, physical activity, sleep, menopausal symptoms, and quality of life, while wearing a Fitbit device to objectively monitor physical activity and sleep throughout the study.

The PILI study team will evaluate the feasibility of the intervention by assessing recruitment, retention, adherence to supplement consumption and study procedures, participant acceptability and tolerability, and completion of biological sample collection and clinical assessments. Preliminary changes in microbiome composition and function, microbial metabolites, and cardiometabolic health outcomes will also be evaluated to generate data that will inform the design of a future larger clinical trial.

This research has the potential to advance understanding of how prebiotic supplementation influences the gut-muscle-metabolism axis during the menopausal transition and to identify a safe, low-cost nutritional strategy to improve cardiometabolic health among perimenopausal women.

Inclusion criteria

• Body mass index: 25 - 40 kg/m2;
• Menstrual cycle irregularity (cycle length outside 21 - 35 days or variation > 7 days) or/and ≥ 2 skipped cycles and interval of ≥ 60 days of amenorrhea; with or without hot flashes or/and night sweats;
• Weight stable within the last 3 months (body weight fluctuations within the 5% of their habitual body weight);
• Spending ≥ 6 hours sitting;
• < 150 minutes per week (50 minutes per day, 3 days per week OR 30 minutes per day, 5 days per week) of moderate to vigorous structured physical activity (i.e., planned intentional physical activity, not incidental movement).

Exclusion criteria

• Recent antibiotic use oral or vaginal (≥ 6months);
• Diagnosed with any chronic disease (e.g., any gastrointestinal condition like IBD, type 2 diabetes, or cancer);
• Prescription of hormone replacement therapy, hormonal contraceptives, probiotics, GLP-1 medications, or weight loss medications
• Smoking;
• Recent blood donation (within the past 8-12 weeks);
• Significant weight changes (≥5%) in the last 4 weeks;
• Use of dietary supplements (unless discontinued 4 weeks prior);
• Participants taking long-term, stable medications for chronic conditions such as hypertension or hyperlipidemia will not be excluded if their medication regimen has been unchanged for at least 2 years, as these treatments are part of their usual health status. Recent medication changes (within the past 6 months), initiation of new prescriptions, or use of medications known to affect metabolic, vascular, vaginal, hormonal, or gastrointestinal function will result in exclusion.
• Fructose intolerance.