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.

  • Creatine for Healthy Aging: Muscle, Strength and Brain Energy

    Creatine for healthy aging showing active older adults strength training with muscle, ATP energy and brain health physiology.

    Creatine monohydrate has moved well beyond sports nutrition. Its strongest healthy-aging evidence centers on muscle, strength, training capacity and lean mass, with an emerging body of research exploring brain energy and cognition.

  • Building Strength as You Age: How Metagenics® UltraMeal Advanced Protein Supports Muscle Health and Longevity

    Building Strength as You Age: How Metagenics® UltraMeal Advanced Protein Supports Muscle Health and Longevity

    Sarcopenia — the age-related loss of muscle mass and strength — can be slowed and even reversed through targeted nutrition. Metagenics UltraMeal Advanced Protein®, recommended by HormoneSynergy® and Dr. Kathryn Retzler, provides clinically formulated protein and nutrients to support muscle health and longevity for adults nationwide.

  • Healthspan vs. Lifespan—Why the Difference Matters

    Healthspan vs. Lifespan—Why the Difference Matters

    Discover why healthspan matters more than lifespan and how HormoneSynergy® Clinic in Portland & Lake Oswego uses longevity medicine, preventive cardiology, and RetzlerRx® supplements to help you live longer, healthier, and stronger. Learn how to optimize energy, vitality, and well-being with evidence-based care and advanced diagnostics.

  • Muscle Protein Synthesis, Protein, and Longevity

    Muscle Protein Synthesis, Protein, and Longevity

    Muscle protein synthesis is the repair and rebuilding process that helps preserve strength, metabolism, insulin sensitivity, and long-term healthspan.

  • Top 10 Metagenics® Supplements for Hormone Balance, Longevity & Everyday Vitality

    Top 10 Metagenics® Supplements for Hormone Balance, Longevity & Everyday Vitality

    Discover the top 10 Metagenics® supplements for hormone balance, immune health, and longevity — available nationwide from HormoneSynergy® / RetzlerRx®. Learn how these science-backed formulas fit into your personalized wellness plan.

  • 10 XYMOGEN® Supplements We Use in Longevity Medicine

    XYMOGEN professional supplements for magnesium, gut health, cardiovascular health, mitochondrial function and longevity medicine at HormoneSynergy.

    XYMOGEN® makes a large professional supplement catalog, but more products do not necessarily mean a better supplement plan. Here are 10 formulations we consider particularly useful for magnesium, vitamin D and K2, gut health, histamine metabolism, stress support, omega-3s, mitochondrial health, glucose metabolism, and CoQ10 support.

  • Calocurb® and Amarasate®: What the Research Shows About Appetite, Cravings and Weight Loss

    Calocurb Amarasate bitter hop extract and gut appetite signaling involving GLP-1, CCK and PYY for metabolic health and weight management.

    Calocurb® uses Amarasate®, a bitter New Zealand hop extract designed to stimulate the gut’s own satiety signals. Human trials now include acute appetite studies and a 24-week randomized weight-loss trial. Here is what the evidence actually shows, and what it does not.

  • Magnesium Benefits and Best Forms for Healthy Aging

    Magnesium for healthy aging showing cellular energy, muscle, cardiovascular, metabolic and brain health pathways.

    Magnesium supports hundreds of enzyme systems involved in energy production, muscle and nerve function, blood pressure, glucose metabolism, relaxation, and brain health. Here is how magnesium fits into longevity medicine, which forms we use, and how to choose between UltraMag and magnesium L-threonate.

  • Innate & Adaptive Immunity: Building a Resilient Defense for Lifelong Health

    tranfer factor rapid response

    Your immune system’s strength depends on the balance of innate and adaptive defenses working together. At HormoneSynergy® Clinic in Portland & Lake Oswego, we help patients build resilience through science-based lifestyle strategies and advanced nutraceuticals like Transfer Factor Rapid Response™ by Researched Nutritionals®. Learn how to strengthen your immunity for lifelong health and longevity.

  • RetzlerRx® Collagen Peptides: Joint, Bone, Skin, and Connective Tissue Support

    Physician reviewing collagen peptides for joint, bone, skin, and connective tissue support with a patient in a modern Portland and Lake Oswego longevity medicine clinic.

    RetzlerRx® Collagen Peptides combine Fortigel®, Fortibone®, and Verisol® hydrolyzed peptides for targeted support beyond generic collagen powders.

  • SECA Body Composition Testing in Portland and Lake Oswego

    Physician reviewing SECA body composition testing, visceral fat, muscle mass, hydration, and metabolic trends with a patient in a modern Portland and Lake Oswego longevity medicine clinic.

    SECA body composition testing helps track fat mass, muscle mass, visceral fat, hydration, and metabolic trends with clinic-level interpretation.

  • HormoneSynergy® & MyFitFoods® | Healthy Meals in Lake Oswego

    HormoneSynergy® & MyFitFoods® | Healthy Meals in Lake Oswego

    At HormoneSynergy® Clinic and RetzlerRx®, we know that nutrition is one of the most powerful drivers of health and longevity. Many of our patients struggle with preparing balanced meals, often turning to fast food or processed options due to busy schedules. That’s why we proudly support MyFitFoods® Lake Oswego, a local business making it easier to enjoy fresh, convenient, and nutrient-rich meals. Together, we share a mission to help the Portland and Lake Oswego community make smarter food choices that support energy, vitality, and lifelong wellness.