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.

  • Your Immune System Ages Too. What Immunosenescence Actually Means

    Medical illustration showing immunosenescence and changes in immune cells and inflammation as the human immune system ages.

    We tend to think about aging in terms of skin, muscle, bone, hormones and memory. The immune system ages with us, too. Immunosenescence helps explain why infections can become harder to fight, vaccines may produce a weaker response and chronic inflammation becomes more common. The useful question is what we can actually do about it.

  • Understanding Statin Phobia: Who’s Pushing It and Why It Can Be Dangerous

    HormoneSynergy® preventive cardiology image showing statin phobia, ApoB, LDL, blood pressure, and cardiovascular risk assessment in Portland and Lake Oswego.

    Statin phobia, fueled by media sensationalism, online misinformation, and alternative health advocates, can have dangerous consequences. For patients at risk of heart disease, avoiding or discontinuing statins due to fear can lead to severe health issues, including heart attacks and strokes. Combatting this phobia through education, balanced information, and open communication with healthcare providers is crucial to ensure that patients receive the care they need.

  • The Ketogenic Diet - Benefits and Considerations

    The Ketogenic Diet - Benefits and Considerations
    It's important to note that individual responses to the ketogenic diet can vary, and what works for one person may not work for another. Before starting any diet, especially one as restrictive as the ketogenic diet, it's advisable to consult with a healthcare provider or a Functional / Integrative medicine practitioner to ensure it aligns with your health goals and needs.
  • Healthy Lifestyle Choices for Longevity: What Actually Matters as We Age

    Healthy adults exercising, eating well and staying socially connected as part of a preventive longevity lifestyle.

    Healthy aging involves far more than eating vegetables and getting enough sleep. Muscle, cardiovascular risk, metabolic health, bone, cognition, relationships and the ability to remain physically capable all matter. Here is the HormoneSynergy approach to the fundamentals of longevity.

  • Microbiome Labs and Gut Health: Probiotics, Prebiotics, Postbiotics and Barrier Support

    Gut microbiome illustration showing probiotics, prebiotics, intestinal barrier health, and microbiome diversity in longevity medicine.

    Microbiome Labs helped popularize a more complete approach to microbiome support, combining spore-based probiotics, targeted prebiotics, and intestinal barrier support. Here is what makes the approach interesting, where the research stands, and how products such as MegaSporeBiotic™ and Total Gut Restoration fit into a broader gut-health strategy.

  • Berberine, Citrus Bergamot and Curcumin for Cholesterol and Heart Health

    Female physician discusses berberine, citrus bergamot, curcumin, cholesterol, and heart health with a patient at HormoneSynergy Clinic.

    Berberine, citrus bergamot, and curcumin may support cholesterol and metabolic health, but they do not replace cardiovascular risk assessment, lifestyle changes, or proven medication when indicated.

  • Carnivore vs. Mediterranean Diet: Which Is Better for Long-Term Health?

    Carnivore and Mediterranean meals compared for long-term health at HormoneSynergy Clinic in Portland, Oregon.

    The Mediterranean diet has substantially stronger evidence for cardiovascular health, metabolic health, and longevity. A carnivore diet may produce short-term changes, but its long-term safety and nutritional adequacy remain uncertain.

  • What is Creatine and what are the benifits of taking a Creatine supplement as we age?

    What is Creatine and what are the benifits of taking a Creatine supplement as we age?
    Creatine, when paired with resistance or strength training, is an effective strategy for maintaining and improving physical and mental health in older adults, helping to mitigate the effects of aging and sarcopenia.
  • Plant- and Protein-Forward Mediterranean Diet: A Practical Approach to Healthy Aging

    Plant- and Protein-Forward Mediterranean Diet: A Practical Approach to Healthy Aging

    The Plant- and Protein-Forward Mediterranean Diet combines the cardiovascular and metabolic strengths of Mediterranean eating with greater attention to protein, muscle preservation, fiber, and individual nutritional needs.

  • Five Essentials for Optimizing Longevity

    Five Essentials for Optimizing Longevity
    To optimize longevity, a combination of proper nutrition, physical activity, and key nutrients plays a crucial role. The Paleo-Mediterranean diet h...
  • What is BDNF and how does it enhance Brain Health and Neuroplasticity in Aging?

    What is BDNF and how does it enhance Brain Health and Neuroplasticity in Aging?
    BDNF stands for Brain-Derived Neurotrophic Factor, which is a protein that plays a crucial role in the development, maintenance, and plasticity of ...
  • What Is the Best Glutathione Supplement? A Buyer’s Guide to Formulation, Testing and Quality

    Clinician evaluates glutathione formulation, dosage, stability, certificate of analysis and manufacturer testing with a patient.

    The word “liposomal” does not guarantee absorption, and “S-acetyl” does not guarantee clinical superiority. Learn how to evaluate glutathione supplements by formulation, dosage, stability, finished-product testing and manufacturer quality.