Alpha-Ketoglutarate and Longevity: What the AKG Trials Actually Show

What alpha-ketoglutarate is

Alpha-ketoglutarate (AKG; also written 2-oxoglutarate, chemical formula C₅H₆O₅) is not an exotic botanical or a designer drug. It is one of the core intermediates of the tricarboxylic acid cycle — the Krebs cycle — that every mitochondrion runs continuously to turn food into energy. Beyond energy metabolism, AKG sits at a metabolic crossroads: it is a nitrogen carrier in amino-acid synthesis, a substrate for collagen formation, and a required co-factor for a large family of enzymes called dioxygenases, which includes the TET and JmjC enzymes that erase and rewrite the epigenetic marks on DNA and histones.^[1] That last role is why AKG keeps appearing in aging research: it is a direct chemical link between the metabolic state of a cell and its epigenetic "software."

The reason anyone treats AKG as a candidate longevity molecule rather than an ordinary nutrient is a simple observation: circulating AKG levels decline substantially with age — by some estimates as much as tenfold between early adulthood and old age. That decline tracks with, and may partly drive, the metabolic and epigenetic drift that defines aging. The obvious question follows: if you put the molecule back, does anything improve?

The animal evidence: a longer, healthier life in mice

The study that launched the current interest was published in Cell Metabolism in 2020 by Asadi Shahmirzadi and colleagues at the Buck Institute. They fed aging C57BL/6 mice AKG in the form of a calcium salt (CaAKG) and tracked them across their remaining lifespan with clinically relevant measures of health.^[2] The results were notable in two distinct ways. Median lifespan increased modestly — on the order of 10–20% depending on sex — but the more striking finding was healthspan: treated animals spent a markedly smaller fraction of their lives frail and sick. On measures of gait, grip, fur condition and frailty index, the mice stayed younger for longer, so the illness at the end of life was compressed into a shorter window.

The proposed mechanism is relevant to why AKG might matter beyond raw energy metabolism. The authors found that AKG raised levels of the anti-inflammatory cytokine interleukin-10 (IL-10) and lowered systemic inflammatory signals, suggesting that part of its benefit runs through dampening the chronic, low-grade inflammation of aging — the same process we cover in inflammaging. A 2025 Cell Metabolism metabolic atlas of aging across twelve mouse organs independently flagged alpha-ketoglutarate as one of the metabolites whose decline helps drive the aging process, reinforcing that this is not a fringe target but one that shows up when researchers map aging from the metabolism outward.^[3]

The human headline: an 8-year drop in biological age

The number that put AKG on supplement shelves came from a 2021 paper in the journal Aging by Demidenko and colleagues.^[4] They performed a retrospective analysis of 42 people who had been taking Rejuvant, a commercial formulation of calcium-AKG combined with small amounts of vitamins A and D. Using the TruAge DNA methylation clock — an epigenetic estimate of biological age of the kind we explain in our piece on epigenetic aging clocks — they compared each person's biological age before and after an average of about seven months of use. On average, biological age dropped by roughly 8 years, and most participants moved in the same direction.

Taken at face value, that is one of the largest biological-age reversals reported for any oral supplement. But the study's own design demands restraint. It was retrospective, it had no placebo or control group, the sample was only 42 self-selected people, and the DNA methylation clock used carries meaningful measurement noise from test to test. Without a control arm there is no way to separate a true AKG effect from regression to the mean, lifestyle changes among motivated supplement-takers, or the ordinary variability of the clock itself. The authors said as much, explicitly calling for a placebo-controlled trial. An 8-year headline built on 42 uncontrolled cases is a hypothesis, not a proof.

The 2026 reality check

That larger analysis has now started to arrive. In 2026, researchers from the Healthy Longevity Translational Research Programme at the National University of Singapore — the group led by Brian Kennedy, a co-author of both the mouse and the original Rejuvant work — published a much bigger real-world analysis in Aging Cell.^[5] Drawing on data from more than 4,200 individuals collected between 2020 and 2025, the cross-sectional arm compared 143 people using calcium-AKG against non-users and found an average reduction in biological age of roughly 1.8 years — real, but a long way from eight.

More telling was the longitudinal arm, which followed the same individuals over time rather than comparing different groups. Here, with only 26 participants, the analysis showed no statistically significant improvement. The most likely explanation is simple lack of statistical power — 26 people is too few to detect a small effect reliably — but that is exactly the point. When the design tightens and the sample that actually tracks change over time shrinks, the dramatic 8-year effect does not reproduce. The honest reading of the current human data is that AKG is associated with a small, plausibly real reduction in epigenetic age, not the age-reversal miracle the early number implied.

The trial that will actually settle it

The missing piece — a randomized, placebo-controlled trial — is under way. The ABLE study, whose protocol was published in GeroScience in 2023, is a double-blind, placebo-controlled randomized trial of 1 gram of sustained-release calcium-AKG per day versus placebo in 120 healthy adults aged 40–60.^[6] Its design is deliberately smart: it enrols only people whose DNA methylation age is already older than their chronological age, the group with the most room to improve, and its primary endpoint is precisely the change in DNA methylation age that the uncontrolled studies measured without a comparator. Secondary endpoints include inflammatory and metabolic blood markers, grip and leg strength, arterial stiffness, skin autofluorescence and aerobic capacity. When ABLE reports, it will be the first fair test of whether calcium-AKG moves an epigenetic clock in humans. Until then, every biological-age claim for AKG rests on uncontrolled data.

How AKG fits with everything else

AKG belongs to a small club of geroprotector candidates — molecules that extend healthy lifespan in animals and are now being pushed toward human validation. It shares the field's central problem with rapamycin and with metabolite supplements like NAD+ precursors: robust, repeatable mouse data, and a stubborn gap where the definitive human trial should be. What sets AKG apart, modestly, is mechanistic plausibility. Unlike a foreign drug, it is an endogenous metabolite the body already relies on; its decline with age is documented; and its role as a co-factor for the epigenetic-editing enzymes gives a coherent reason why restoring it might touch a methylation clock rather than merely making numbers wobble.

None of that makes it proven. The doses that worked in mice are, per kilogram of body weight, far higher than the roughly 1 gram of calcium-AKG a day used in humans, and animal results have themselves been mixed across studies. The rational position is the same one that applies across this field: AKG is one of the more biologically credible longevity supplements, the harm from a gram of a Krebs-cycle molecule appears low in the short term, and the extraordinary claims attached to it have not yet survived a controlled trial. The unglamorous interventions with the deepest human evidence — cardiorespiratory fitness, muscle, sleep, metabolic health — remain the better bet while the AKG trials read out.