Tier 3 — preclinical

Alpha-ketoglutarate stabilizes redox homeostasis and improves arterial elasticity in aged mice

T. Niemiec, J. Sikorska, A. Harrison, M. Szmidt, E. Sawosz, E. Wirth-Dzieciolowska, J. Wilczak, S. Pierzynowski

Journal of Physiology and Pharmacology 2011 Volume 62, issue 1, pages 37–43

Bibliography

DOI
PubMed: PMID 21451208
Funding: No funding statement in the source.
Competing interests: None declared.

Study snapshot

Design	Controlled feeding study, four-arm parallel-group design in mice
Model	Outbred mice selected for high body weight (shortened lifespan phenotype), Warsaw University of Life Sciences colony
Sample	40 mice at randomisation (10 per group); endpoint numbers Ca-AKG n=10, Na-AKG n=8, aged control n=8
Intervention	Standard chow (Labofeed H) supplemented with 2% calcium α-ketoglutarate (Ca-AKG) or 2% sodium α-ketoglutarate (Na-AKG); aged controls received unsupplemented standard chow
Duration	6 months of supplementation in aged groups (mice 6–12 months of age); young control fed standard chow for 1 month prior to termination at 2 months
Endpoints	Total antioxidant status (TAS) in blood plasma; Superoxide dismutase (SOD) activity in erythrocytes; Glutathione peroxidase (GPx) activity in erythrocytes; Thiobarbituric acid reactive substances (TBARS) in blood plasma; TBARS in liver tissue; Aortic elastic recoil (abdominal aorta, ex vivo force-transducer measurement)

What the study showed, in plain terms

This 2011 study asked whether α-ketoglutarate (AKG), a small molecule produced by the body's energy-generating Krebs cycle, could push back against two things that go wrong with vascular ageing in mice: a rise in oxidative stress and a loss of aortic elasticity. The researchers used two chemically distinct salt forms — calcium α-ketoglutarate (Ca-AKG) and sodium α-ketoglutarate (Na-AKG) — because the salt form was expected to affect how the compound behaves in the gut and how long it stays available for absorption.

The team fed aged mice (12 months old) a standard diet supplemented with 2% of one AKG salt or the other for six months, and compared them with aged mice on an unsupplemented diet and with young 2-month-old mice. They measured antioxidant capacity, oxidative damage markers, and the elastic recoil of abdominal aorta segments in a bench-top mechanical rig.

Ca-AKG produced the clearest results. It restored the aged mice's blood antioxidant status toward youthful levels, cut oxidative damage in the liver by roughly half, and nearly doubled the elastic recoil of aortic tissue compared with unsupplemented aged mice. Na-AKG changed the profile of individual antioxidant enzymes but did not reproduce the arterial elasticity benefit. The authors attributed Ca-AKG's advantage partly to its slower dissolution in the gut, which extends the window during which the compound is available for absorption.

Key findings

Ca-AKG raised plasma total antioxidant status (TAS) in aged mice to a level significantly higher than aged controls; Na-AKG did not reproduce this effect.
Ca-AKG reduced plasma TBARS (a lipid peroxidation marker) in aged mice significantly below aged controls.
Ca-AKG reduced liver TBARS to approximately 50% of the aged control value — the largest tissue-level oxidative-damage reduction observed.
Na-AKG increased erythrocyte glutathione peroxidase (GPx) activity to the highest level recorded across all groups and reduced superoxide dismutase (SOD) activity.
Aortic elastic recoil in Ca-AKG-fed aged mice was 5.57 ± 1.31 × 10⁻⁶ N ms⁻¹ mg⁻¹ wet weight, compared with 2.91 ± 0.32 × 10⁻⁶ in aged controls — a 91% increase (p<0.05).
Na-AKG produced a smaller, non-significant ~32% increase in aortic elastic recoil (3.84 ± 0.61 × 10⁻⁶ N ms⁻¹ mg⁻¹ wet weight).
The authors proposed that Ca-AKG's advantage over Na-AKG reflects its slower dissolution in the gut, extending the absorption window.

What this study can and cannot tell us

Small groups (n=8–10 per arm at endpoint), limiting statistical power for secondary endpoints.
The mouse line was an outbred stock selected for high body weight and a shortened lifespan — a non-standard model whose responses may not generalise to conventional laboratory or wild-type mice, let alone humans.
Only one dose was tested (2% dietary inclusion) for each salt; no dose-response data.
Aortic elasticity was measured ex vivo on excised abdominal aortic segments under stepwise mechanical tension. This is not the same as in vivo pulse-wave velocity, arterial compliance, or endothelial function measured in intact circulation.
Mechanistic pathways discussed in the paper — proline-driven collagen turnover, GPR99 signalling — were not directly assayed in this study.
No human data. Direct translation of the dose, timing, or magnitude of effect to human vascular ageing is not supported by this study alone.
The paper predates the current wave of AKG longevity research (Chin 2014, Asadi Shahmirzadi 2020, Wang 2020 osteoporosis, Demidenko/Rejuvant 2021) and should be read as an early functional signal rather than a definitive vascular finding.