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 resource focused on evidence-based strategies for extending healthspan, preventing chronic disease, and supporting healthy aging. Led by Dr. Kathryn Retzler, our educational articles translate advanced clinical science into practical insights that help individuals in Portland, Lake Oswego, Oregon, and across the United States better understand metabolism, hormones, cardiovascular risk, brain health, body composition, gut health, sleep, recovery, and the biology of aging.

Our goal is to help readers move beyond wellness marketing and isolated health claims. Longevity medicine is not one lab, one supplement, one diet label, one scan, or one online trend. It is a systems-based model that asks better clinical questions and interprets data in context.

Explore the Core Systems of Longevity Medicine

Longevity medicine is not built around a single symptom, diagnosis, or optimization hack. It is built around understanding the major biological systems that influence how people age, how chronic disease develops, and how earlier pattern recognition can support better long-term outcomes.

This page organizes our physician-guided educational content into clearer topic hubs so readers can explore the areas most relevant to metabolic health, hormone balance, cardiovascular prevention, body composition, brain health, gut health, sleep, recovery, fatigue, food quality, supplements, and healthy aging.

Recently added:

Metabolic Health & Insulin Resistance

Foundational guides on insulin resistance, blood sugar regulation, metabolic syndrome, glucose patterns, and early cardiometabolic risk.

Hormones, Transitions & Healthy Aging

Hormone-focused resources covering transitions, testing, physiology, menopause, testosterone, thyroid, and clinical context.

  • The Realities of Becoming a Naturopathic Physician: What Medical School Does Not Prepare You For

    Becoming a licensed naturopathic physician requires years of medical education, board examinations, and commitment. What happens after graduation is less predictable. Scope of practice varies by state, residencies are limited, professional acceptance remains uneven, and many young physicians discover that building a career also means learning how to build a business.

  • Metagenics StayStrong+: Collagen, Creatine, Joint Health, and Healthy Aging

    Metagenics StayStrong+ collagen and creatine supplements for muscle, joint, connective tissue, and healthy aging support.

    Metagenics has expanded collagen beyond the usual skin-and-beauty category with StayStrong+, a new line combining targeted collagen ingredients with creatine, UC-II®, vitamin D, magnesium, and connective-tissue support. The formulas are interesting, but the type of collagen and the dose still deserve a closer look.

  • Save 20% on Your First Metagenics® Order

    Save 20% on Your First Metagenics® Order

    Celebrate our 25-year partnership with Metagenics®. New customers receive 0% off their first order plus free shipping through our practitioner portal. 

  • Top 20 Metagenics Products + 20% Off | HormoneSynergy®

    Metagenics new patient 20% off first order through HormoneSynergy provider ID KATRET4650, with free shipping, Subscribe and Save benefits, registration instructions, and Metagenics quality standards.

    Explore 20 popular Metagenics® formulas for gut health, metabolic health, inflammation balance, menopause support, stress resilience, muscle health, and healthy aging. New customers registering through the HormoneSynergy® practitioner connection can receive 20% off their first order, with the discount applied automatically and no coupon code required.

  • The Big Bold Health Longevity Study: Himalayan Tartary Buckwheat, Immune Aging, and the 47% Finding

    Big Bold Health Longevity Study of Himalayan Tartary Buckwheat, epigenetic aging, immune aging and polyphenol biology

    A 90-day human pilot study of Big Bold Health HTB Rejuvenate found intriguing changes in epigenetic aging, immune-cell patterns, and biological pathways associated with immune aging. The often-quoted 47% result is real, but it came from a small subgroup. Here is what the study actually found and why the larger story may be more interesting.

  • Microbiome Labs Mega IgG2000 Powder vs. Capsules: What Is the Difference?

    MegaIgG2000 powder and capsules compared for serum-derived bovine immunoglobulin and gut barrier support.

    MegaIgG2000 is a dairy-free, serum-derived bovine immunoglobulin supplement available as a powder or capsules. Both provide 2 grams of ImmunoLin® per serving, but the powder contains slightly more IgG and allows more flexible dosing, while the capsules offer greater convenience. 

  • CBD and THC Creams for Pain: Do They Actually Work?

    CBD and THC creams for pain illustration showing topical cannabinoid absorption through skin and CB1, CB2, and TRPV1 pain-signaling pathways.

    CBD and THC creams are widely sold for sore muscles, arthritis, joint stiffness, and inflammation. The biology is plausible, but the clinical evidence is much thinner than the marketing. Here is what we know about cannabinoid receptors in the skin, topical versus transdermal delivery, arthritis and neuropathic pain, muscle soreness, and why the formulation may matter as much as the cannabinoid itself.

  • Estrogen in Men: Why Lower Is Not Always Better During Testosterone Therapy

    Estrogen and estradiol physiology in men during testosterone therapy showing aromatization, bone, muscle, body composition and metabolic health.

    Estradiol matters for bone, sexual function, body composition and metabolism in men. Learn why routine estrogen suppression during TRT may be unnecessary.

  • High LDL, Low Triglycerides, Great Metabolic Health: Does ApoB Still Matter?

    High LDL and ApoB with low triglycerides and good metabolic health illustrated in a preventive cardiology assessment.

    Low triglycerides, good insulin sensitivity, normal blood pressure, and excellent fitness are all favorable for cardiovascular health. But do they make a very high LDL-C or ApoB less important? The biology is more nuanced than either side of the cholesterol debate usually admits.

  • Statins and Muscle Loss: What a New Study Really Shows

    Statins, muscle mass, grip strength, and cardiovascular longevity illustrated with artery and skeletal muscle imagery.

    A large UK Biobank study linked long-term statin use with faster declines in grip strength and appendicular lean mass. The signal deserves attention, but the widely repeated “73% muscle loss” interpretation is wrong, and newer studies have not confirmed that statins increase sarcopenia risk.

  • Sarcopenic Obesity and the Brain: Why Muscle Loss May Matter More Than Weight

    Sarcopenic obesity and brain health illustration showing skeletal muscle, body composition and cerebral circulation in relation to dementia risk and cognitive longevity.

    A large 2026 prospective study found that sarcopenic obesity, the combination of excess body fat with low muscle mass and function, was associated with a 34% higher risk of dementia. The strongest and most consistent signal was not body weight. It was declining muscle strength. The findings reinforce an important longevity principle: preserving muscle while improving body composition may matter far more than simply making the number on the scale smaller.

  • Can Statins Raise Your Calcium Score While Reducing Heart Risk?

    Statins and coronary calcium showing a rising CAC score alongside reduced noncalcified plaque and denser, more stable coronary plaque.

    A rising coronary artery calcium score usually sounds like worsening heart disease. After statin therapy, the interpretation becomes more complicated. Statins can reduce cardiovascular events, slow growth of noncalcified plaque, and shift existing coronary plaque toward a denser, more calcified phenotype. Because the standard Agatston calcium score gives greater weight to dense calcium, the CAC number can rise even while plaque is becoming more stable. This is why current cardiovascular guidelines do not recommend repeating CAC scans to judge whether statin therapy is working.