What is biological age?
How it is measured, why the major epigenetic clocks disagree with each other, and what the measurement actually predicts.
SDAI BioAge Science
The mechanism, before the marketing.
Biological age, epigenetic clocks and alpha-ketoglutarate explained at the level of what is actually established, what is plausible, and what is still an open question. Written for people who would rather understand the thing than be sold it.
Start here
Alpha-ketoglutarate explained
The citric acid cycle role, the cofactor role in DNA demethylation, the age-related decline, and what has been demonstrated.
Sustained-release AKG
Why AKG's short half-life motivates the formulation, and why a better release profile is not the same as an efficacy result.
Three things worth knowing before you read anything else in this category
There is no single clock
Horvath, Hannum, PhenoAge, GrimAge and DunedinPACE were trained on different outcomes and give different answers on the same sample. When a test reports your biological age, the first question is which clock produced it.
Association is not administration
Observational cohort studies with "associated with" in the title cannot separate a compound from the person who chose to take it. When a marketing page turns that into a dose producing a measured reduction, the claim has been upgraded in transit.
Lowering a clock is not proven to help
Interventions can shift a clock reading. Nobody has yet shown that shifting the reading changes the outcome the clock predicts. A great deal of longevity marketing rests on that unstated assumption.
Want a number rather than an explanation?
Our sister site runs a biological age estimator that publishes its entire weighting table, including why it contains no supplement input.