Alpha-Ketoglutarate

Alpha-ketoglutarate (AKG) sits at a metabolic crossroads: it is produced constantly inside every cell as part of the Krebs cycle and used to make several amino acids. Because circulating AKG appears to fall with age, researchers have tested whether restoring it can slow aging.

The cleanest evidence is a Buck Institute mouse study. Middle-aged mice fed calcium-AKG showed a 12% increase in median lifespan without significantly extending maximum lifespan, and the treated mice showed a striking compression of morbidity: pro-inflammatory cytokines fell, and physical markers of frailty (fur condition, body condition, activity) improved for longer before decline set in, meaning mice stayed healthier for a larger fraction of their remaining life even without living dramatically longer overall [1][2]. That is a real, peer-reviewed, published result in Cell Metabolism, and the compressed-morbidity framing, extending healthspan more than raw lifespan, is one of the more carefully qualified claims in the rodent longevity literature.

The human evidence is a different story and one that requires more scrutiny than marketing materials typically apply. A widely cited 2021 paper reported that 42 individuals taking Rejuvant, a proprietary calcium-AKG-based formulation, showed an average 8-year decrease in DNA-methylation-based biological age after roughly 7 months of use, with a reported p-value of 6.5 x 10^-12 [3]. That is a striking number, but the study design has real limits: it was a retrospective analysis of self-selected supplement users, not a randomized controlled trial; there was no placebo arm; participants' methylation age was measured with a single commercial test (TruAge) rather than multiple validated clocks; and the study's authors are affiliated with the company selling the supplement and the company running the epigenetic test used to measure the outcome. A retrospective, uncontrolled, industry-linked study of 42 people reporting an 8-year age reversal is a hypothesis-generating result, not proof that AKG reverses biological aging in humans.

A proper randomized trial exists to test this directly: the ABLE study (Alpha-ketoglutarate supplementation and BiologicaL agE) is a double-blind, placebo-controlled RCT of 1 g sustained-release Ca-AKG versus placebo over 6 months in 120 middle-aged adults selected specifically for having an epigenetic age older than their chronological age, with DNA methylation age as the primary outcome [4]. As of the study protocol's publication, ABLE was designed to give the field the controlled data the 2021 retrospective study could not provide; whether its results confirm or contradict the earlier 8-year figure is the real test of whether Rejuvant's claim holds up.

Blueprint materials list AKG-containing supplement use in some public breakdowns of longevity stacks broadly, though calcium-AKG specifically is not confirmed as part of Bryan Johnson's own published protocol; readers should not assume self-experimenter adoption where it has not been documented.

Critics of the Rejuvant retrospective data point to the exact design problems above: no control group means no way to separate a true drug effect from regression to the mean, seasonal variation, or the fact that people who pay for a longevity supplement often simultaneously improve diet, sleep, and exercise, any of which independently affects DNA methylation clocks. An 8-year reversal claim built on an uncontrolled, industry-affiliated sample of 42 people is precisely the kind of result a randomized trial like ABLE exists to either confirm or falsify.

AKG has one legitimate, peer-reviewed mouse lifespan and healthspan result behind it; its human epigenetic-age reversal claim comes from a small, uncontrolled, company-linked study that a proper RCT has not yet replicated.