Explore Dr. Retzler’s HormoneSynergy® Longevity Medicine Resource Library

Longevity Medicine, Functional Wellness & Anti-Aging Insights from HormoneSynergy®

Welcome to the HormoneSynergy® Longevity Medicine Blog, a physician-guided clinical library led by Dr. Kathryn Retzler. Our articles cover the systems that most often shape health with age: metabolic health, hormones, cardiovascular and kidney risk, body composition, bone and muscle, brain health, sleep, gut health, nutrition, supplements, and the biology of aging.

The library is organized around clinical questions rather than trends. Some articles review new research. Others explain testing, treatment, nutrition, or a condition patients commonly encounter. Across the collection, the standard is the same: evidence first, appropriate uncertainty, and enough clinical context to separate useful medicine from wellness marketing.

Start with the HormoneSynergy® Longevity Medicine Framework

New & recently updated:

Metabolic Health & Insulin Resistance

Clinical resources on insulin resistance, glucose regulation, metabolic syndrome, visceral fat, prediabetes, obesity and GLP-1-based care within a broader longevity medicine plan.

Kidney Health & Cardiovascular-Kidney-Metabolic Health

Kidney health belongs in the same clinical conversation as blood pressure, diabetes, insulin resistance, obesity and cardiovascular risk. These resources cover early detection, CKD, albuminuria, nutrition and CKM health.

Gut Health, Microbiome & Immune Signaling

Clinical education on the microbiome, intestinal barrier, fiber, inflammation, gut-brain signaling, immune biology and the growing connections between gut, metabolic and kidney health.

Food Quality, Vitamins, Supplements & Wellness Claims

Evidence-based guidance on nutrient gaps, supplement quality, interactions, food claims and longevity products, with an emphasis on where supplementation helps and where marketing outruns the evidence.

  • L-Theanine for Stress, Focus, Sleep, and Longevity: A Longevity Medicine Perspective

    L-theanine and longevity clinical banner for longevity medicine showing calm focus stress resilience and sleep support HormoneSynergy Portland Oregon USA

    L-theanine is best known for helping people feel calmer without feeling sedated, but its relevance in longevity medicine goes beyond stress support alone. It fits into a broader conversation about nervous system balance, sleep quality, mental clarity, recovery, and the physiologic cost of chronic stress.

  • Methylated B12 and Longevity: What It Does and Who May Need It

    Methylated B12 and longevity clinical banner for longevity medicine showing brain methylation and cellular energy support HormoneSynergy Portland Oregon USA
    Vitamin B12 is essential for neurologic function, red blood cell formation, DNA synthesis, and homocysteine metabolism. Methylcobalamin is one supplemental form, but the real clinical questions are whether B12 is needed, why it may be low, and what dose makes sense.
  • Copper and Longevity: Mitochondrial, Antioxidant, and Connective Tissue Support in Longevity Medicine

    Copper and longevity clinical banner for longevity medicine showing mitochondrial antioxidant and connective tissue support HormoneSynergy Portland Oregon USA

    Copper is an essential trace mineral involved in energy production, antioxidant defense, connective tissue integrity, and healthy iron utilization. In longevity medicine, it matters not because more is better, but because balance matters.

  • Alpha-Lipoic Acid (ALA) and Longevity: Metabolic, Mitochondrial, and Antioxidant Support

    Alpha lipoic acid ALA and longevity clinical banner showing mitochondrial and metabolic support for longevity medicine HormoneSynergy Portland Oregon USA

    Alpha-lipoic acid (ALA) is a powerful metabolic and antioxidant compound that supports mitochondrial function, insulin sensitivity, and cellular protection. In longevity medicine, it plays a key role in bridging metabolic and oxidative stress pathways.

  • Creatine and Longevity: Muscle, Brain, and Metabolic Performance in Longevity Medicine

    Creatine and longevity clinical banner showing muscle and brain energy systems with ATP and metabolic support cues in HormoneSynergy style

    Creatine is one of the most studied and clinically useful compounds in performance and longevity medicine. Beyond muscle strength, it supports brain energy, metabolic resilience, and healthy aging across both men and women.

  • Selenium and Longevity: Thyroid, Antioxidant, and Immune Support in Longevity Medicine

    Selenium and Longevity clinical editorial banner with subtle thyroid, antioxidant, and immune support cues in HormoneSynergy

    Selenium is a trace mineral with outsized importance in longevity medicine. It supports thyroid hormone metabolism, antioxidant defense, immune resilience, and cellular protection, but more is not always better. Here is how selenium fits into a thoughtful, evidence-based longevity strategy.

  • Zinc and Longevity: Hormones, Immunity, Metabolism, and Cellular Function

    Zinc and longevity clinical illustration showing vascular and cellular environment with metabolic and immune system support in longevity medicine

    Zinc is a critical trace mineral involved in hormone balance, immune regulation, metabolic function, and cellular repair. In longevity medicine, optimal zinc status supports testosterone, immune resilience, and long-term health.

  • ApoB vs LDL-P: Which Marker Better Reflects Cardiovascular Risk?

    ApoB vs LDL-P clinical illustration comparing total atherogenic particle burden and LDL particle number in cardiovascular risk

    ApoB and LDL particle number (LDL-P) both measure atherogenic particle burden, but they are not identical. Understanding how they overlap—and where they differ—helps clarify cardiovascular risk beyond traditional cholesterol labs.

  • Citrus Bergamot and Longevity: Cholesterol Balance, Lipid Support, and Cardiometabolic Wellness

    Citrus bergamot and longevity clinical illustration showing cholesterol balance, lipid support, and cardiometabolic wellness

    Citrus bergamot is a polyphenol-rich botanical used in longevity medicine to support healthy cholesterol metabolism, lipid balance, and broader cardiometabolic wellness. At HormoneSynergy®, it is currently included in RetzlerRx® Cholest Protect alongside berberine and Curcumin C3 Complex® as part of a preventive longevity medicine strategy.

  • Curcumin and Longevity: Inflammation, Joint Health, and Cellular Resilience

    Curcumin and longevity clinical illustration showing inflammation balance, joint health, antioxidant protection, and cellular resilience

    Curcumin, the active compound in turmeric, is widely used in longevity medicine for its role in supporting healthy inflammatory balance, joint comfort, and cellular resilience. Advanced formulations like BCM-95® and curcumin with BioPerine® are designed to enhance absorption and effectiveness.

  • Berberine and Longevity: Glucose Metabolism, Cardiometabolic Health, and Healthy Aging

    Berberine and longevity clinical illustration showing glucose metabolism, cardiometabolic support, and metabolic resilience

    Berberine is a plant-derived compound commonly used in longevity medicine to support healthy blood glucose metabolism, metabolic balance, and cardiometabolic wellness. At HormoneSynergy®, current RetzlerRx® berberine options include a focused dihydroberberine formula and a broader cardiometabolic blend paired with citrus bergamot and curcumin.

  • Active Folate (5-MTHF): What It Does and Where the Marketing Goes Too Far

    Active folate 5-MTHF medical illustration showing DNA synthesis, red blood cells, neurological function and homocysteine metabolism.

    Active folate plays a legitimate role in methylation, blood formation, neurologic function and homocysteine metabolism. But an MTHFR variant is not a diagnosis, methylfolate is not automatically superior, and pregnancy guidance still specifically calls for folic acid.