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.

  • Akkermansia and Longevity: Gut Barrier, Metabolic Health, and the Microbiome Connection

    A clinical editorial banner for Akkermansia and longevity featuring a refined microbiome and gut barrier visual style in HormoneSynergy®

    Akkermansia muciniphila is one of the most discussed next-generation probiotic strains in metabolic and gut-health research. This guide explains what Akkermansia is, why it matters in longevity medicine, and which HormoneSynergy® products currently feature this strain.

  • Nicotinamide Riboside and Longevity

    Nicotinamide riboside and longevity clinical banner showing NAD cellular energy, mitochondrial function, and DNA repair in HormoneSynergy
    AI Overview: Nicotinamide riboside (NR) is a form of vitamin B3 that acts as a precursor to NAD⁺, a molecule essential for cellular energy, mito...
  • NAD⁺ and Longevity: Cellular Energy, Mitochondria, and Healthy Aging

    NAD⁺ and longevity illustration showing mitochondrial energy production, cellular metabolism, DNA repair, and healthy aging.

    NAD⁺ is essential to cellular energy production, mitochondrial metabolism, DNA repair, and cellular signaling. Here is where NAD⁺ biology fits into longevity medicine, what happens as levels decline with age, and what human research tells us about supporting the pathway.

  • Apigenin and Longevity

    Apigenin and Longevity clinical editorial banner showing sleep, GABA signaling, and nervous system calming in HormoneSynergy

    Apigenin is a plant flavonoid known for its calming effects on the nervous system, GABA signaling support, and sleep quality. In longevity medicine, it represents a subtle but powerful “nervous system layer” that supports recovery, sleep depth, and long-term resilience.

  • Rhodiola and Longevity

    Rhodiola and Longevity clinical editorial banner showing stress response, cognitive performance, and nervous system balance in HormoneSynergy

    Rhodiola rosea is an adaptogenic herb often used for stress resilience, mental performance, and fatigue support. In longevity medicine, it fits as a targeted “stress layer”—helping support energy, recovery, and nervous system balance when demand exceeds capacity.

  • Astaxanthin and Longevity

    Astaxanthin and Longevity clinical editorial banner showing mitochondrial, oxidative, skin, and vascular health themes in HormoneSynergy

    Astaxanthin is a potent carotenoid antioxidant often discussed for mitochondrial support, oxidative stress balance, skin protection, and vascular health. In longevity medicine, it is best understood as a targeted support layer—not a shortcut—within a broader strategy of metabolic, cardiovascular, and cellular health.

  • Quercetin and Longevity

    Quercetin and Longevity clinical editorial banner showing vascular, inflammation, and oxidative stress support themes in a clean HormoneSynergy

    Quercetin is a plant flavonoid often discussed for healthy inflammation signaling, oxidative stress balance, vascular support, and nutrient synergy. In longevity medicine, it is less about hype and more about context: where it may fit, what it may support, and how it compares with the bigger metabolic, vascular, and lifestyle picture.

  • Resveratrol and Longevity: Polyphenols, Cellular Stress Defense, and Healthy Aging Pathways

    Resveratrol and Longevity clinical editorial hero image with subtle polyphenol, vascular, and cellular defense cues in HormoneSynergy®

    Resveratrol is one of the most discussed polyphenols in longevity medicine because of its links to oxidative stress defense, vascular health, metabolic signaling, and healthy aging research. It is best understood as a mechanistically interesting support compound, not a stand-alone anti-aging solution.

  • Spermidine and Longevity: Autophagy, Cellular Renewal, and Healthy Aging Pathways

    Spermidine and Longevity clinical editorial image showing autophagy and cellular renewal in HormoneSynergy®

    Spermidine is a naturally occurring polyamine involved in cellular renewal and autophagy. In longevity medicine, it is gaining attention for its role in cellular cleanup, metabolic regulation, and healthy aging biology.

  • Taurine and Longevity: Mitochondrial Stability, Cardiometabolic Health, and Cellular Resilience

    Taurine and Longevity clinical editorial image showing mitochondrial, metabolic, and cardiovascular balance in HormoneSynergy®

    Taurine is a foundational but under-discussed nutrient in longevity medicine. It supports mitochondrial function, cardiovascular physiology, metabolic health, and nervous system balance—making it one of the most quietly important compounds in a physiology-first longevity framework.

  • Ashwagandha and Longevity: Stress Resilience, Sleep, Brain, and Recovery Support

    Ashwagandha and longevity clinical banner for longevity medicine showing stress resilience sleep support brain recovery and nervous system balance HormoneSynergy Portland Oregon USA

    Ashwagandha is one of the most clinically relevant adaptogens in longevity medicine because it connects stress biology, sleep quality, cognitive resilience, recovery, and whole-body physiologic balance. It matters not because it is trendy, but because chronic stress has real metabolic, hormonal, and neurologic consequences.

  • 5-HTP and Longevity: Mood, Sleep, Appetite, and Nervous System Support

    5-HTP and longevity clinical banner for longevity medicine showing mood sleep appetite and nervous system support HormoneSynergy Portland Oregon USA

    5-HTP is best known as a serotonin precursor, but in longevity medicine its relevance goes beyond mood support alone. It fits into a broader conversation about sleep quality, appetite regulation, nervous system balance, emotional resilience, and the physiologic effects of chronic stress.