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Knife Down

Knife Down

Written by: Lily Johnston MD MPH
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"Knife Down" is what a surgeon says in the OR when she puts her scalpel down so no one gets hurt — and it’s the mission here: put the knife down, long before anyone needs to use it.


Knife Down is a podcast about how to actually invest in your health so you can live longer, stronger, and with less time in doctors’ offices. The core focus is the world’s leading cause of death—cardiovascular disease—and what to do about it before it shows up as a catastrophe.


Hosted by a vascular surgeon on a mission to put herself out of business, the show translates cutting-edge science on prevention, metabolic health, and longevity into real-world strategies you can use in clinic or at your kitchen table. Expect evidence, nuance, and zero wellness hype—plus the occasional dark joke about the state of modern medicine.

© 2026 Knife Down
Hygiene & Healthy Living Physical Illness & Disease
Episodes
  • Surgeon Reacts to the KETO-CTA 'Scandal'
    Jul 23 2026

    The KETO-CTA trial got retracted this year, and most of the internet treated it like a takedown. The authors pulled their own paper because they found real errors in the analysis. That took integrity. I react to how other creators have covered this retraction, walk through what the errors actually were, and make the case that watching scientists correct themselves in public is what good science looks like.

    📚 STUDY DISCUSSED
    Soto-Mota A, Norwitz NG, Manubolu VS, Kinninger A, Wood TR, Earls J, Feldman D, Budoff M. Longitudinal Data From the KETO-CTA Study: Plaque Predicts Plaque, ApoB Does Not. JACC Adv. 2025;4(7):101686. PMID: 40192608. https://pubmed.ncbi.nlm.nih.gov/40192608/ (Retracted Publication)

    Expression of Concern: "Plaque Begets Plaque. ApoB Does Not: Longitudinal Data from The KETO-CTA Trial" [JACC: Advances, Volume 4, Issue 7, July 2025, Article 101686]. JACC Adv. 2026;5(3):102607. PMID: 41906601. https://pubmed.ncbi.nlm.nih.gov/41906601/

    ▶️ WATCH NEXT
    Is Ezetimibe the Secret to Preventing Dementia? Surgeon Reacts to @nicknorwitzMDPhD: https://youtu.be/Rzz2g9gRL_8
    Is Lower LDL Actually Better? New Research Has an Answer: https://youtu.be/Q2lvd9ND7rA

    ⚕️ DISCLAIMER
    This channel is for education, not medical advice. I'm a board-certified vascular surgeon, but I'm not your surgeon, and nothing here replaces a conversation with your own physician.Sign up for more information on my own practice here: https://corsighthealth.com/

    High Quality 3rd-party tested supplements at Fullscript (10% discount): https://us.fullscript.com/welcome/ljohnstonmd/store-start

    Other tools for optimal health (note these are affiliate links):
    Home BP Cuff: https://amzn.to/49Cq7rh
    Sonicare Toothbrush: https://amzn.to/3KllfMS
    WaterPik: https://amzn.to/4894Xi8
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    Personal Blender: https://amzn.to/4pyNGGl
    True Nutrition Protein: https://oken.do/q2xzqeqw
    Glass Meal Prep Containers: https://amzn.to/4ocEPJ2
    Sleep Mask: https://amzn.to/48fSJV5
    Air Purifier: https://amzn.to/4puzTQZ

    ___________________________
    🧬 About Dr. Lily Johnston

    Dr. Johnston is a double board-certified vascular and general surgeon in San Diego, specializing in metabolic and cardiovascular prevention. She’s the founder of CorSight Health and a passionate advocate for reimagining how medicine approaches chronic disease.

    Show More Show Less
    33 mins
  • Carnivore Bloodwork: Best Case, Not the Whole Case
    Jul 22 2026

    Dr. Abs pulled bloodwork from 50 of his carnivore patients — cholesterol up, triglycerides down, A1C and CRP better across the board. It's a genuinely good data set. It's also the best-case scenario, not the average one.

    I'm reacting to walk through what those numbers actually mean, why cherry-picked wins don't tell you what happens to everyone on this diet, and what two Virta Health trials add to the picture: LDL-C did rise over two years, but it was driven by a shift toward larger, less atherogenic particles, and carotid imaging showed no progression of arterial disease.

    Original video: https://youtu.be/CygSkDzDOHE

    Studies referenced:
    Bhanpuri et al., 2018, Cardiovascular Diabetology — PMID 29712560 — https://pubmed.ncbi.nlm.nih.gov/29712560/
    Athinarayanan et al., 2020, Cardiovascular Diabetology — PMID 33292205 — https://pubmed.ncbi.nlm.nih.gov/33292205/

    Sign up for more information on my own practice here: https://corsighthealth.com/

    High Quality 3rd-party tested supplements at Fullscript (10% discount): https://us.fullscript.com/welcome/ljohnstonmd/store-start

    Other tools for optimal health (note these are affiliate links):
    Home BP Cuff: https://amzn.to/49Cq7rh
    Sonicare Toothbrush: https://amzn.to/3KllfMS
    WaterPik: https://amzn.to/4894Xi8
    Apple Watch with sleep & HR monitoring: https://amzn.to/3XaUn5d
    Oura Ring with sleep, cycle, and recovery monitoring: https://amzn.to/4riyhLS
    Intake Breathing Nasal Support: https://amzn.to/48dfQQ1
    Personal Blender: https://amzn.to/4pyNGGl
    True Nutrition Protein: https://oken.do/q2xzqeqw
    Glass Meal Prep Containers: https://amzn.to/4ocEPJ2
    Sleep Mask: https://amzn.to/48fSJV5
    Air Purifier: https://amzn.to/4puzTQZ

    ___________________________
    🧬 About Dr. Lily Johnston

    Dr. Johnston is a double board-certified vascular and general surgeon in San Diego, specializing in metabolic and cardiovascular prevention. She’s the founder of CorSight Health and a passionate advocate for reimagining how medicine approaches chronic disease.

    #MetabolicHealth #CardiovascularPrevention #HeartHealth #Longevity #InsulinResistance #DrLilyJohnston #DrLily #WomenInMedicine #Surgeon #VascularSurgeon #PreventiveMedicine #PADPrevention #HeartAttackRisks #HealthPortfolio #California #SanDiego #Arizona #Virginia #Minnesota

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    39 mins
  • Do Viagra and Cialis Help You Live Longer? What This Study Actually Found
    Jul 21 2026

    Chapters:
    00:00 - Introduction & AMA Catch-up
    00:28 - Does Fibromyalgia Affect Heart Health?
    01:43 - Advanced Markers for Inflammation (hsCRP, oxLDL)
    03:04 - Upcoming LIVE AMA Details
    03:48 - Is it Safe to Stop Lipitor for High Cholesterol?
    05:23 - The "700 Point Drop" in CAC Score: What is Plaque-X?
    07:51 - Testosterone & The FDA Black Box Warning Update
    08:33 - Deep Dive: Do Viagra and Cialis Impact Mortality?
    09:54 - Study Funding and Conflicts of Interest
    10:51 - How PDE5 Inhibitors Actually Work
    12:53 - Observational Studies vs. Clinical Trials
    14:41 - Understanding the Dataset (TriNetX)
    16:41 - How Patient Cohorts are Defined
    19:54 - Comparing Cialis vs. Viagra for Heart Benefits
    21:26 - Why Prostate Health Matters in This Research
    24:21 - Breaking Down the Five Key Outcomes
    26:30 - Statistical Matching: Making the Groups Fair
    30:03 - The Results: Mortality, Stroke, and Dementia Risk
    33:57 - Absolute vs. Relative Risk Reduction
    37:29 - Tadalafil’s Half-Life Advantage
    39:18 - Crossing the Blood-Brain Barrier
    41:04 - Study Limitations: What We Might Have Missed
    42:24 - The "Partnership" Factor in Longevity Data 43:32 - Final Thoughts: Is it Time for a Label Change?

    In this session, I'm diving into your questions from our last AMA and taking a deep look at a fascinating new study on PDE5 inhibitors like Cialis (tadalafil) and Viagra (sildenafil). We explore whether these medications could have a role in longevity, heart health, and even dementia prevention. I also address questions on fibromyalgia, stopping statins, and the latest on testosterone and cardiovascular risk.

    Sign up for more information on my own practice here: https://corsighthealth.com/

    High Quality 3rd-party tested supplements at Fullscript (10% discount): https://us.fullscript.com/welcome/ljohnstonmd/store-start

    Other tools for optimal health (note these are affiliate links):
    Home BP Cuff: https://amzn.to/49Cq7rh
    Sonicare Toothbrush: https://amzn.to/3KllfMS
    WaterPik: https://amzn.to/4894Xi8
    Apple Watch with sleep & HR monitoring: https://amzn.to/3XaUn5d
    Oura Ring with sleep, cycle, and recovery monitoring: https://amzn.to/4riyhLS
    Intake Breathing Nasal Support: https://amzn.to/48dfQQ1
    Personal Blender: https://amzn.to/4pyNGGl
    True Nutrition Protein: https://oken.do/q2xzqeqw
    Glass Meal Prep Containers: https://amzn.to/4ocEPJ2
    Sleep Mask: https://amzn.to/48fSJV5
    Air Purifier: https://amzn.to/4puzTQZ

    ___________________________
    🧬 About Dr. Lily Johnston

    Dr. Johnston is a double board-certified vascular and general surgeon in San Diego, specializing in metabolic and cardiovascular prevention. She’s the founder of CorSight Health and a passionate advocate for reimagining how medicine approaches chronic disease.

    #MetabolicHealth #CardiovascularPrevention #HeartHealth #Longevity #InsulinResistance #DrLilyJohnston #DrLily #WomenInMedicine #Surgeon #VascularSurgeon #PreventiveMedicine #PADPrevention #HeartAttackRisks #HealthPortfolio #California #SanDiego #Arizona #Virginia #Minnesota

    Show More Show Less
    44 mins
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