Tier 2 — strong

Alpha-Ketoglutarate as a Molecule with Pleiotropic Activity: Well-Known and Novel Possibilities of Therapeutic Use

Barbara Zdzisińska, Aleksandra Żurek, Martyna Kandefer-Szerszeń

Archivum Immunologiae et Therapiae Experimentalis 2017 Volume 65, issue 1, pages 21–36

Bibliography

DOI: 10.1007/s00005-016-0406-x
PubMed: PMID 27326424
PubMed Central: PMC5274648
Funding: This work was supported by research Grant No 2013/11/B/NZ4/04557 from State Funds for Scientific Research National Science Centre (NCN), Poland.
Competing interests: Not stated. The published article contains no formal competing interests declaration section. Published open access under Creative Commons Attribution 4.0 International License.

Study snapshot

Design	Narrative review
Model	Human clinical populations (post-surgical, burns, hemodialysis, osteopenia); rodent, poultry and porcine models; in vitro cell culture (fibroblasts, thymocytes, tumour cell lines)
Sample	Not applicable — narrative review synthesising the AKG therapeutic literature to 2015
Intervention	Ornithine α-ketoglutarate (OKG), calcium α-ketoglutarate, sodium α-ketoglutarate, and cell-permeable AKG esters (octyl-AKG, 1-trifluoromethyl benzyl-AKG) delivered orally, enterally, parenterally, or in vitro at study-specific doses
Duration	Not applicable
Endpoints	Protein and nitrogen metabolism in catabolic states; Antioxidant activity and cyanide antagonism; Immunomodulatory effects on phagocyte and lymphocyte function; Bone anabolic effects (density, collagen synthesis, prolidase activity); Anticancer activity via HIF-1α destabilisation and epigenetic modulation

What the study showed, in plain terms

Alpha-ketoglutarate (AKG) is a small molecule your body makes as part of the Krebs cycle, the process cells use to turn food into energy. This 2017 review, from a Polish team at Maria Curie-Sklodowska University, pulls together roughly four decades of research on what AKG does beyond producing energy — and where it might be useful as a therapy.

The authors describe AKG as pleiotropic, meaning it does many different things depending on the tissue and situation. It supplies building blocks for glutamine and other amino acids, acts as an antioxidant, activates enzymes that build collagen and control epigenetic marks on DNA, and can neutralise cyanide poisoning. On this basis, ornithine α-ketoglutarate (OKG) and calcium/sodium AKG have been used clinically for post-surgical recovery, burns, hemodialysis, and postmenopausal bone loss, with mixed but generally supportive results.

The review is a mechanistic and translational overview rather than a systematic review. It is one of the most-cited reference works on AKG's non-metabolic roles and is used across the Ca-AKG cluster as an anchor for how AKG might affect bone, protein turnover, and safety. It does not evaluate the branded delayed-release calcium-AKG products (Rejuvant) that dominate today's supplement market — those studies came later.

Key findings

Circulating AKG declines with age. The review cites Harrison and Pierzynowski (2008) reporting that blood AKG drops from µM to ng/mL concentrations after age 40 — the observation that underpins later interest in AKG as a geroprotector.
Bioavailability of oral AKG is limited. In pig studies, up to 40% of ingested AKG is degraded to CO₂ in the intestinal mucosa on first pass; roughly 20% reaches the bloodstream. Half-life in blood is under 5 minutes. Cell-permeable esters improve delivery in vitro.
Postmenopausal bone data. A 24-week study of sodium AKG plus calcium in women with osteopenia showed roughly a 37% reduction in serum CTX (a bone-resorption marker) versus calcium-only controls, and higher lumbar spine bone density. This is the Filip 2007 signal that anchors the Ca-AKG bone-health article in this cluster.
Protein-sparing in catabolic states. Multiple clinical studies of OKG in burns, post-surgery, trauma, and elderly malnutrition show improved nitrogen balance, reduced muscle proteolysis, faster wound healing, and stimulation of insulin, GH, and IGF-1 secretion.
Immunomodulation. OKG and AKG enhance neutrophil ROS production, macrophage cytotoxicity, and TNF-α secretion in stressed animal models; counteract thymic involution in burn injury; and increase NK-cell cytotoxicity in tumour-bearing rats.
Cofactor for 2-oxoglutarate-dependent dioxygenases (2-OGDDs). AKG is an obligatory substrate for over 60 human enzymes including prolyl hydroxylases (regulate HIF-1α and collagen synthesis), TET1–3 (DNA demethylation), and Jumonji-C histone demethylases — the mechanistic basis for AKG's epigenetic effects.
Anticancer signals. Exogenous AKG destabilises HIF-1α, inhibits VEGF-driven angiogenesis in Hep3B and Lewis lung carcinoma models, and reverses the pseudohypoxia state in SDH/FH/IDH-mutant tumours. AKG combined with 5-fluorouracil showed additive anti-tumour effects in mouse xenografts.
Redox homeostasis in aged mice. AKG supplementation stabilised antioxidant enzyme activity and arterial elasticity in aged mice to levels comparable to young animals (Niemiec 2011).

What this study can and cannot tell us

Narrative, not systematic. This is a mechanism-and-therapeutic overview, not a systematic review with prespecified inclusion criteria, risk-of-bias assessment, or quantitative synthesis. Study selection and emphasis reflect the authors' framing rather than a reproducible protocol.

Predates the modern Ca-AKG longevity evidence base. The literature cut-off is 2015. It therefore does not cover Shahmirzadi 2020 (the Buck Institute mouse lifespan study), Demidenko 2021 (the retrospective Rejuvant biological-age cohort), or any of the ongoing Ca-AKG RCTs (ABLE, NCT07114536). Readers using this paper as an anchor should pair it with a more recent review such as Gyanwali 2022 or Wu 2023.

Human clinical data reviewed is largely from the 1980s–2000s. Much of the post-surgical, burns, and hemodialysis work used ornithine α-ketoglutarate rather than calcium α-ketoglutarate, and dose regimens, endpoints, and control groups vary substantially between studies. Direct extrapolation to modern 1 g/day Ca-AKG supplementation is not supported.

Bioavailability caveat is important. The review itself notes AKG's poor cellular penetration in some in vitro settings and short blood half-life, which raises unresolved questions about the plasma exposure achievable with oral dosing — a caveat that applies directly to today's Rejuvant and DoNotAge Pure Ca-AKG formulations.

No competing interests statement. The published article contains no formal COI declaration section; readers cannot verify absence of industry ties from the paper itself.