Fecal Microbiota Transplantation (FMT) to Slow Biological Aging

• Voluntary written informed consent signed prior to any study-related procedures.
• Age between 45 and 80 years (inclusive) at the time of screening.
• Classified as "metabolically neglected" with documented pre-disease conditions or regulated early-stage chronic disorders.
• Accelerated biological aging rate 1.1, OR between 1.05 and 1.099 combined with chronic low-grade inflammation (inflammaging).
• Preserved cognitive function with a Montreal Cognitive Assessment (MoCA) score between 24 and 30 points.
• Physical ability to perform computerized cognitive tests on a touch-screen tablet.
• Commitment to maintaining stable dietary and physical activity habits throughout the study period.
• Possession of a home freezer and ability to strictly comply with cold-chain storage logistics for investigational products and stool samples.
• Demonstrated ability to swallow large capsules.
• Adequate baseline laboratory parameters (such as blood counts and kidney function).
• For women of childbearing potential: agreement to use a highly effective method of contraception throughout the study and for 30 days post-intervention.
• Readiness to ensure presence at the registered home address to receive scheduled frozen-chain courier shipments.

Exclusion Criteria:

• Systemic antibiotic therapy within 12 weeks prior to baseline.
• Supplementation with any commercial pre- or probiotics within 4 weeks prior to baseline.
• Diagnosed malignancy within the past 5 years (except fully cured basal cell carcinoma or cervical cancer in situ).
• Participation in any other clinical study or trial within 30 days prior to consent or during this study.
• Pregnancy, breastfeeding, or planning a pregnancy during the study and for 30 days post-intervention.
• Known hypersensitivity, intolerance, or allergy to any component of the investigational product (MBiotix HBI Caps), placebo, preparation antibiotics (Neomycin, Metronidazole), antibiotic placebo, or bowel cleansing solution (macrogols).
• Pre-existing hearing loss, chronic tinnitus, or diagnosed vestibular disorder. History of or active peripheral neuropathy of any etiology.
• Myasthenia gravis or other neuromuscular transmission disorders.
• Concurrent, ongoing use of loop diuretics, other aminoglycoside antibiotics, or known nephrotoxic drugs.
• Severe, unstable, or uncontrolled comorbidities, including NYHA Class III/IV heart failure, unstable angina, or myocardial infarction within the past 6 months.
• Severe hepatic impairment (Child-Pugh Class C) or severe renal impairment (eGFR \< 30 mL/min/1.73 m²).
• Active, severe psychiatric disorders (e.g., severe depression with active suicidal ideation, psychotic disorders, unstable bipolar disorder).

Diagnosis of progressive neurodegenerative diseases (Parkinson's, Alzheimer's) or moderate-to-advanced dementia.

• Active, clinically significant inflammatory bowel disease (Crohn's disease, ulcerative colitis) or other severe gastrointestinal disorders.
• Evidence of gastrointestinal mucosal damage (ulceration, perforation, bleeding) within 7 days prior to the first product dose.
• Clinically significant immunosuppression, including chronic systemic corticosteroids, HIV infection with a CD4+ cell count \< 200/µl, history of solid organ or hematopoietic stem cell transplantation.
• Active infection requiring antibiotics during the induction phase or anticipated antibiotic use during the first 7 days post-induction.
• Prior fecal microbiota transplantation (FMT) treatment for indications other than recurrent C. difficile infection.
• Significant dysphagia precluding safe capsule ingestion.
• Inadequate baseline laboratory parameters (such as blood counts and kidney function).
• Any medical condition or circumstance judged by the Principal Investigator to compromise participant safety or protocol adherence.
• Anticipated inability to comply with study procedures, such as missing scheduled follow-up visits, lacking reliable home freezer storage, or having a lifestyle/occupation that prevents proper cold-chain product handling or consistent attendance.