Karl Pfleger (@KarlPfleger) / X

Karl Pfleger

5,309 posts

Karl Pfleger

@KarlPfleger

Founder of nonprofit AgingBiotech.info Investor in rejuvenation startups: portfolio on LinkedIn Organizer of VitaminDforAll.org AI/ML Stanford PhD & ex-Google

San Francisco

Joined March 2020

Pinned
Karl Pfleger
@KarlPfleger
Apr 22
The 2 Longevity Fields... New post on a topic of great importance. Long, but something I feel strongly about. Broadly Slowing Aging vs. Divide-and-Conquer Rejuvenation: How to tell the difference and why acknowledging both matters (link in next post)
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Karl Pfleger
@KarlPfleger
Apr 24, 2021
A surprising 97% of adults in India are vitamin D insufficient, <30ng/ml, the Endocrine Soc min. For elders: 98%<30 & 91%<20 (clinical deficiency). See ncbi.nlm.nih.gov/pmc/articles/P… How many fewer would be dying in India if basic deficiency/insufficiency had been remedied?
Karl Pfleger
@KarlPfleger
Sep 16, 2024
Short report: The state of the mitochondria portion of the aging biotech field: 50 companies! $1.4+B raised 700+ people 150+ clinical trials many MoAs/targets: mitophagy, transplant, fission, NAD+, UrolithinA, CD38, PINK1, PPARδ, DRP1, USP30, Complex 1, OMA1, & more Read on:
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Karl Pfleger
@KarlPfleger
Dec 16, 2023
The aging field doesn't discuss enough the key top-level distinction between the 2 main therapeutic paradigms: slow aging or reverse it. I support slowing aging as much better than traditional medicine, but it pains me to see many in the field disparage or ignore reversal & I
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Karl Pfleger
@KarlPfleger
Jan 27, 2022
At this point, it is beyond question that Vitamin D Deficiency (VDD) is a significant risk factor for Covid just like age, obesity, comorbidities. Many dozens of studies show this & correlation-doesn't-imply-causation isn't a valid objection to classification as a risk factor. 🧵
Karl Pfleger
@KarlPfleger
Mar 4, 2025
A 2nd important recent longevity development that is too-little discussed in the field: The first 2 FDA approved allogeneic stem cell therapies, both in past 2 years. - off-the-shelf - mass-producible - likely relevant for multiple age-related pathologies This is important!
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Karl Pfleger
@KarlPfleger
Aug 11, 2022
There are now (at min) 4 big systematic meta-analyses of vitamin D & Covid since Dec'21. 3 study D levels & 2 supplementation. Newest both. Strong, consistent, & highly statistically significant results: Low D raises & supplementation lowers all stages of Covid risk by ~1.5-3x 🧵
Karl Pfleger
@KarlPfleger
Dec 9, 2020
Announcing a new open letter: Over 100 scientists, doctors & authorities call for more vitamin D for COVID-19. 50+ professors. 50+ medical doctors. Many of the most renowned vitamin D experts in the world. 19 countries. vitamind4all.org/letter.html Clear call to action #VitaminDforAll
Karl Pfleger
@KarlPfleger
Feb 7, 2025
It's 2025 & I'm getting excited & even optimistic for the next 5 years in the aging/longevity sector based on looking around at what's going on. It's not that the ultimate solutions will emerge that quickly, but the seeds of huge change may be upon the world soon.
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Karl Pfleger
@KarlPfleger
Mar 23, 2025
The Economist this week has 2 articles on human enhancement, inc longevity. It's even the cover story. Good! But longevity is lumped in w/ sport & cognitive enhancement & BCI. The label superhuman is used. So not the focus piece on aging's horrors the field deserves. Details:
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Karl Pfleger
@KarlPfleger
Jul 1, 2024
Direct-to-consumer aging clocks give very inconsistent answers. I tried TruDiagnostic, Elysium, GlycanAge, & reg blood draw for PhenoAge on same day in Feb & from same venous blood draw at LabCorp, except Elysium's uses saliva which I did right before going to LabCorp. Notes: 🧵
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Karl Pfleger
@KarlPfleger
Oct 24, 2024
There's controversy over whether aging should be classified as a disease. I'm doing a debate on it tonight. Complex question with many angles. Here's a document with thoughts from several perspectives to try to help move the global conversation forward:
docs.google.com
Is Aging A Disease?
Is Aging A Disease? Karl Pfleger Oct 2024 There is a lot of controversy about whether aging should be considered to be a disease or not. Among other arguments, advocates for the idea think that if...
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Karl Pfleger
@KarlPfleger
Feb 27, 2025
Replying to @DrSamuelBHume
Now stratify by dose, BMI, baseline 25OHD, whether study titrated dose to achieve 25OHD>20ng/ml or ideally 30ng, & whether outcomes only recorded after enough time for dose to achieve sufficiency. Meta-analyses of flawed studies give flawed answers. See
Karl Pfleger
@KarlPfleger
Dec 6, 2023
Data from the new TargetD trial suggests that prior vitamin D trials were flawed: news-medical.net/news/20231113/… Many people, even professionals, still think vitamin D was a false profit that was disproven by big RCTs. This view is very flawed, for several reasons. A brief history:
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Karl Pfleger
@KarlPfleger
Sep 3, 2022
Replying to @DrJBhattacharya
Booster requirements based on shot count w/o regard to recency of last dose are now indefensible, as are rules not counting prior infections (for non elderly/immunocompromised). Good new Aug31 NEJM review nejm.org/doi/full/10.10… No evidence boosting long ago reduces transmission.
nejm.org
Covid-19 Vaccines — Immunity, Variants, Boosters | NEJM
The protective effects of vaccination and prior infection against severe Covid-19 are reviewed, with proposed directions for future research, including mucosal immunity and intermittent vaccine boo...