I read research studies incessantly — it is part of how I have come to be an early adopter of treatments that even years later, some of my colleagues don't know about. But that habit has also made me allergic to the way science gets sold. Open any feed and you will find a "breakthrough" anti-aging molecule, a supplement that "reverses" aging, a headline promising what the study underneath it never claimed.

So in this letter I want to hand you something durable: a short, practical set of questions you can ask of any health claim, so you can tell the signal from the noise yourself. You do not need a medical degree to do this. You need a handful of habits.

Habit 1: Ask what kind of study it is

Not all evidence is equal. The single most useful thing you can learn is the rough hierarchy. At the bottom: anecdotes and test-tube studies. In the middle: observational studies, which can show that two things travel together but cannot prove one causes the other. Near the top: randomized controlled trials, where people are assigned by chance to treatment or no treatment, which is the cleanest way we have to separate cause from coincidence. At the very top: systematic reviews that pool many good trials together.

Most "eating X is linked to longer life" headlines come from observational data. That is not worthless — it is where hypotheses are born — but "linked to" is not "causes." People who take vitamins, for instance, also tend to exercise, sleep, and eat better; untangling the vitamin from the lifestyle is genuinely hard.

Habit 2: Ask whether it was even done in humans

This one matters enormously in the aging field, because some of the most exciting science is, so far, mostly about mice. Rapamycin is a good example: fed late in life, it extended lifespan in genetically diverse mice — a striking, legitimate finding.1 Metformin, a common and inexpensive diabetes drug, has enough intriguing data that researchers proposed a formal human trial, TAME, designed to test whether it can slow aging-related disease.2

I find this work genuinely thrilling. But notice the gap: a result in a mouse, or a worm, or a dish of cells is a reason to investigate — not a reason to act. The biology of aging is real and increasingly well-mapped, across what researchers now describe as the interacting "hallmarks of aging."3 The science is moving fast. Translation to humans moves slower, and honest writing keeps the two clearly separated.

Habit 3: Ask what they actually measured

Here is where a lot of hype hides. Did the study measure something that matters to you — living longer, fewer heart attacks, more strength, better function — or did it measure a surrogate, a lab number presumed to stand in for those things? A supplement that nudges a biomarker in the right direction has not been shown to help you live better until it is tested against an outcome you can feel. Surrogates are useful signposts, but a signpost is not the destination, and the graveyard of medicine is full of interventions that moved a number and helped no one.

Habit 4: Ask "how much," not just "whether"

Watch for relative numbers presented without the absolute ones. "Cuts your risk by 50%" sounds enormous. But if it lowers a risk from two in a thousand to one in a thousand, that is the same 50% — and a very different thing in real life. Always look for the absolute change and the number of people studied. A dramatic percentage drawn from a tiny study is fragile; small studies routinely produce big numbers that vanish when the work is repeated.

Habit 5: Ask who paid, and whether anyone has repeated it

A single study is a starting point, never a verdict. Findings that hold up are the ones other groups can reproduce. It is worth knowing — soberingly — that a famous analysis argued that, for a range of reasons including small samples, flexible analysis, and publication pressure, most published research findings may be false.4 That is not a reason for cynicism; it is a reason for patience. Real effects survive replication. And it is always fair to ask who funded the work and who profits if you believe it.

Why I am telling you this

You might expect a physician to say "just trust me." I am asking for the opposite. I want you to be able to check the claims — including mine. When I tell you in these letters that something is worth your attention, I want you to be equipped to go read the study yourself, see the evidence, and bring it to your own physician as an informed partner rather than a passive recipient.

This is the antidote to the clinical inertia I keep returning to. The pace of medicine is too often out of step with the pace of discovery — but the remedy is not blind enthusiasm for every shiny new molecule. It is disciplined optimism: genuine excitement about what the evidence supports, paired with a steady unwillingness to be fooled. That combination is exactly how I have found the treatments that made a real difference for my patients, and it is the habit I most want to pass along.

Read everything. Believe carefully. The good stuff holds up.

Dr. Marc Gitterle is a physician in wound care and hyperbaric medicine and the author of Growing Young: A Doctor's Guide to the NEW Anti-Aging.

References

  1. Harrison DE, Strong R, Sharp ZD, et al. Rapamycin fed late in life extends lifespan in genetically heterogeneous mice. Nature. 2009;460(7253):392–395. https://doi.org/10.1038/nature08221
  2. Barzilai N, Crandall JP, Kritchevsky SB, Espeland MA. Metformin as a tool to target aging. Cell Metab. 2016;23(6):1060–1065. https://doi.org/10.1016/j.cmet.2016.05.011
  3. López-Otín C, Blasco MA, Partridge L, Serrano M, Kroemer G. Hallmarks of aging: an expanding universe. Cell. 2023;186(2):243–278. https://doi.org/10.1016/j.cell.2022.11.001
  4. Ioannidis JPA. Why most published research findings are false. PLoS Med. 2005;2(8):e124. https://doi.org/10.1371/journal.pmed.0020124

Sources via PubMed.