The Longevity Letter
Health claims, read with care.
My take on new tests, treatments, and health advice, with the studies behind them and the questions they leave open.
A direct note from Hillary
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Begin with The Supplement Stack
Which supplements I would consider, which I would skip, and what to check about dose, form, and safety.
For clinicians and founders
Building health products or care systems?
The CareCore Stack covers the work of running a health company: clinical oversight, patient care, and day-to-day operations. You can subscribe to it separately at CareCore.
Read or join The CareCore Stack (opens in a new tab)Recent letters
Browse the full newsletter archiveOzempic made old mice live longer. What about us?
A look at GLP-1 research, from mouse lifespan to human trials, and why the distinction matters for treatment decisions.
Read the letterTwo supplements I like. One I don't.
How research and personal experience changed my views on vitamin D, creatine, and NAD supplements.
Read the letterWhy I broke up with fibermaxxing
Why I stopped chasing a daily fiber number and started paying closer attention to the source and my symptoms.
Read the letterI Raised My Omega-3 Level. Then I Read the Trials.
What happened when I compared my improved omega-3 blood test with the evidence for preventing heart disease.
Read the letterFrom the archive
Earlier letters
Selected earlier issues are also available here on the site.













































