Alpha-Ketoglutarate (AKG / Calcium AKG)

Endogenous TCA cycle intermediate
Evidence Level
Limited
3 Clinical Trials
6 Documented Benefits
2/5 Evidence Score

Alpha-ketoglutarate (AKG) is a compound central to the body's energy-producing Krebs cycle and to amino acid metabolism. It is used by athletes for performance and recovery, sometimes as arginine-AKG for blood-flow support, and a calcium form (Ca-AKG) has drawn interest in longevity research, where it has shown promising effects on aging markers in animals. Doses vary by form and purpose, so product labeling is the guide. As a natural metabolic compound, AKG is generally well tolerated, though long-term human data for its longevity use is still developing, and those who are pregnant or on medication should check with a doctor.

Studied Dose Ca-AKG 1,000 mg/day sustained-release (1-2 g/day); post-surgical 2-30 g/day. Ca-AKG salt preferred over free AKG.
Active Compound Alpha-ketoglutarate (alpha-KG, 2-oxoglutarate), a TCA cycle intermediate. Forms: calcium AKG (Ca-AKG, most stable), ammonium AKG, sodium AKG.

Benefits

Biological age reduction

A longitudinal observational study followed 42 self-reported healthy individuals taking Rejuvant (sustained-release Ca-AKG + sex-specific vitamins) for 4-10 months and reported an average 8-year reduction in biological age (DNA methylation test) over 7 months. Substantial effect size if real. Critical caveats: self-reported, no placebo control, single methylation clock, possible selection bias, small sample, and Ca-AKG combined with vitamins (cannot attribute to AKG alone). Hypothesis-generating, not confirmatory.

Able Phase 2 RCT ongoing

The Able trial (National University of Singapore Phase 2 RCT) is testing Ca-AKG vs placebo for 6 months in 120 middle-aged adults (40-60 years) with biological age higher than chronological age. Primary outcome: biological age change. Will provide more rigorous evidence than the Rejuvant observational study. Ongoing — results pending. Critical for definitively establishing or refuting biological age effects.

Animal lifespan extension across multiple species

AKG extends lifespan in fruit flies, C. elegans roundworms, and mice. A mouse study showed Ca-AKG reduced frailty and enhanced longevity (compression of morbidity). Mechanism: caloric restriction mimetic via inhibiting ATP synthase and TOR, activating AMPK. Foundational preclinical evidence supporting human longevity research interest.

Bone density and strength support

Animal studies and limited human evidence suggest Ca-AKG supports bone density. Mechanism: stimulates collagen synthesis (proline hydroxylation requires AKG cofactor) and provides calcium for mineralization. Some human RCTs in osteoporosis showed bone marker improvements. Useful potential adjunct for skeletal health, particularly in older adults.

Wound healing and protein synthesis

Older clinical research showed AKG (often as ornithine α-ketoglutarate, OKG) improves nitrogen balance in surgical patients and burn victims. Improves wound healing and reduces protein catabolism. Mechanism via amino acid synthesis support and growth hormone secretion. Clinical use in some European hospitals as nutritional adjunct.

Muscle protein synthesis support (preclinical)

AKG provides nitrogen carriers for amino acid synthesis (transamination reactions), supporting muscle protein synthesis and reducing protein catabolism in stress states. Animal evidence supports anabolic effects; human translation in athletic/aging contexts is incomplete.

Mechanism of action

1

TCA cycle intermediate (energy metabolism)

AKG is one of eight TCA cycle intermediates — converted to succinyl-CoA via α-ketoglutarate dehydrogenase. Critical for glucose, fatty acid, and amino acid oxidation. Energy production substrate. Provides direct metabolic support for cellular energy demands.

2

Substrate for dioxygenases (epigenetic regulation)

AKG is a required cofactor for 2-OG-dependent dioxygenases, including TET enzymes (DNA demethylation), JmjC histone demethylases (chromatin modification), prolyl hydroxylases (collagen synthesis, HIF regulation), and many others. Supplementation may support epigenetic regulation, a proposed mechanism for the observed biological age effects.

3

Caloric restriction mimetic via ATP synthase / TOR / AMPK

Animal studies show AKG inhibits ATP synthase and TOR (target of rapamycin) signaling while activating AMPK pathway — mimicking effects of caloric restriction (the most reliable known longevity intervention in animals). Mechanism for lifespan extension observed in flies, worms, mice.

4

Glutamate-glutamine cycling and nitrogen metabolism

AKG combines with ammonia via glutamate dehydrogenase to form glutamate — central nitrogen disposal pathway. Used clinically (post-surgery) to manage nitrogen balance and support amino acid synthesis. Mechanism for protein-anabolic effects in catabolic states.

5

Calcium delivery (Ca-AKG specifically)

Ca-AKG salt provides both alpha-ketoglutarate and calcium — useful for bone health and as practical delivery mechanism. Calcium AKG enhances oral stability and bioavailability vs free AKG. Bone density benefits may relate to combined AKG + calcium effects rather than AKG alone.

Clinical trials

1
Rejuvant (Ca-AKG) Biological Age

Longitudinal observational study (Demidenko O, Barardo D, Budovskii V, Finnemore R, Palmer FR 3rd, Kennedy BK, Budovskaya YV 2021, Aging 13(22):24485-24499, doi:10.18632/aging.203736).

42 self-reported healthy individuals taking Rejuvant (sustained-release Ca-AKG + sex-specific vitamins) for 4-10 months. Biological age measured by TruAge DNA methylation test (Horvath-derived clock) before/during/after treatment.

Average 8-YEAR reduction in biological age (TruAge DNA methylation) over average 7 months Rejuvant supplementation. Substantial effect if real. Critical caveats: (1) observational/uncontrolled design, no placebo, (2) self-reported subjects with potential selection bias, (3) single DNA methylation clock, (4) Rejuvant is combination product (AKG + vitamins), (5) sponsored by Ponce de Leon Health (commercial interest), (6) small sample. Most-cited human evidence for AKG biological age effects but methodologically limited.

2
Asadi — Ca-AKG in Mice (Foundational Animal)

Mouse longevity study (Asadi Shahmirzadi A, Edgar D, Liao CY, Hsu YM, Lucanic M, Asadi Shahmirzadi A, Wiley CD, Gan G, Kim DE, Kasler HG, Kuehnemann C, Kaplowitz B, Bhaumik D, Riley RR, Kennedy BK, Lithgow GJ 2020, Cell Metab 32(3):447-456.e6, doi:10.1016/j.cmet.2020.08.004).

C57BL/6 mice received Ca-AKG supplementation. Frailty, lifespan, and healthspan measured.

Ca-AKG reduced frailty and enhanced longevity in mice — compression of morbidity (mice lived longer and with less age-related decline). Mechanism via inflammation reduction (reduced IL-6, IL-10) and improved healthspan markers. Foundational animal evidence supporting Ca-AKG's emergence as 'longevity supplement.' Critical mouse-to-human translation gap — animal lifespan studies do not reliably predict human supplementation effects.

3
Able Trial — Phase 2 Ca-AKG vs Placebo (Ongoing)

Phase 2 randomized double-blind placebo-controlled trial (NCT05706389). National University of Singapore.

120 healthy middle-aged adults (40-60 years) with biological age higher than chronological age. Randomized to Ca-AKG or placebo for 6 months. Primary outcome: biological age change.

Currently ongoing. Will provide more rigorous evidence than observational study. Critical trial for the field — randomized placebo-controlled design with adequate sample size to detect biological age effects. Results pending. Independent of commercial Rejuvant sponsor. Important for definitively establishing or refuting Ca-AKG biological age effects.

Side effects and drug interactions

Common Potential side effects

Generally well-tolerated; doses up to 6 g/day generally safe in clinical/research contexts.
Mild GI upset (nausea, abdominal discomfort) at high doses.
Allergic reactions: rare.
Pregnancy/lactation: insufficient data.
Long-term safety beyond 12 months: limited data.
Calcium AKG: provides ~10-15% calcium by weight — relevant for those with hypercalcemia or kidney stones.

Important Drug interactions

Calcium-containing forms: may interact with bisphosphonates, levothyroxine, fluoroquinolones — separate by 4 hours.
Iron supplements: calcium content of Ca-AKG may reduce non-heme iron absorption; separate by 1-2 hours.
Generally no significant clinical interactions with most medications.
Compatible with most longevity, metabolic, and cardiovascular supplements.
Theoretical: substrates of AKG-dependent dioxygenases (TET, JmjC) — clinical relevance unclear.

Frequently asked questions about Alpha-Ketoglutarate (AKG / Calcium AKG)

What is alpha-ketoglutarate (AKG) used for?

Alpha-ketoglutarate (AKG) is a compound central to cellular energy (the Krebs cycle) and amino acid metabolism. It is used for exercise and recovery, and a form called Ca-AKG is studied in longevity research for healthy aging.

What is AKG good for?

It is used by athletes for performance and recovery (sometimes as arginine-AKG for pumps), and is of growing interest in longevity research, where calcium-AKG has shown promising effects on aging markers in animals. Human longevity evidence is early.

How much alpha-ketoglutarate should I take?

Doses vary by form and purpose; follow product labeling. Longevity-focused calcium-AKG products provide a set daily amount, while sports forms (like arginine-AKG) differ.

Is alpha-ketoglutarate safe?

It is generally well tolerated, as it is a natural metabolic compound. Long-term human data for its longevity use is still developing. As with any supplement, those who are pregnant or on medication should check with a doctor.

What is Alpha-Ketoglutarate?

Alpha-ketoglutarate (AKG) is a compound central to the body's energy-producing Krebs cycle and to amino acid metabolism. It is used by athletes for performance and recovery, sometimes as arginine-AKG for blood-flow support, and a calcium form (Ca-AKG) has drawn interest in longevity research, where it has shown promisi…

What is Alpha-Ketoglutarate used for?

Alpha-Ketoglutarate is researched primarily for Longevity, Bone Health, and Muscle & Recovery. A longitudinal observational study followed 42 self-reported healthy individuals taking Rejuvant (sustained-release Ca-AKG + sex-specific vitamins) for 4-10 months and reported an average 8-year reduction in biological age (DNA methylation…

What is the recommended dosage of Alpha-Ketoglutarate?

The clinically studied dose is Ca-AKG 1,000 mg/day sustained-release (1-2 g/day); post-surgical 2-30 g/day. Ca-AKG salt preferred over free AKG. Always follow the product label and check with a healthcare provider for personal advice.

Is Alpha-Ketoglutarate safe, and does it have side effects?

For most healthy adults, Alpha-Ketoglutarate is well tolerated at studied doses. Reported effects can include: Generally well-tolerated; doses up to 6 g/day generally safe in clinical/research contexts. Mild GI upset (nausea, abdominal discomfort) at high doses. It may also interact with some medications. Alpha-Ketoglutarate is not right for everyone, so check with a healthcare provider first if you are pregnant or breastfeeding, have a medical condition, or take prescription medication.

Does Alpha-Ketoglutarate interact with any medications?

Possible interactions include: Calcium-containing forms: may interact with bisphosphonates, levothyroxine, fluoroquinolones — separate by 4 hours. Iron supplements: calcium content of Ca-AKG may reduce non-heme iron absorption; separate by 1-2 hours. If you take prescription medication, check with a pharmacist or doctor before using it.

How strong is the scientific evidence for Alpha-Ketoglutarate?

NutraSmarts rates the evidence for Alpha-Ketoglutarate as Limited (2 out of 5). It is backed by 3 clinical trials and 4 cited references summarized on this page. A higher rating reflects more, larger, and better-designed human studies.

References(4 citations)

Evidence ratings on NutraSmarts are based on the totality of human clinical research, with emphasis on randomized controlled trials, meta-analyses, and systematic reviews. The references below directly support claims made throughout this page.

  1. Demidenko O, Barardo D, Budovskii V, Finnemore R, Palmer FR, Kennedy BK, Budovskaya YV Rejuvant®, a potential life-extending compound formulation with alpha-ketoglutarate and vitamins, conferred an average 8 year reduction in biological aging, after an average of 7 months of use, in the TruAge DNA methylation test Aging (Albany NY). 2021;13(22):24485-24499. doi:10.18632/aging.203736.PubMedUsed to support: Human intervention study (n=42) of calcium alpha-ketoglutarate (Ca-AKG) formulation showing an average 8-year reduction in biological age measured by DNA methylation clock after ~7 months of use — directly supports the biological age reduction benefit (small, uncontrolled study; as noted in benefits).
  2. Chin RM, Fu X, Pai MY, Vergnes L, Hwang H, Deng G, Diep S, Lomenick B, Meli VS, Monsalve GC, Hu E, Whelan SA, Wang JX, Jung G, Solis GM, Fazlollahi F, Kaweeteerawat C, Quach A, Nili M, Krall AS, Godwin HA, Chang HR, Faull KF, Guo F, Jiang M, Trauger SA, Saghatelian A, Braas D, Christofk HR, Clarke CF, Teitell MA, Petrascheck M, Reue K, Jung ME, Frand AR, Huang J The metabolite α-ketoglutarate extends lifespan by inhibiting ATP synthase and TOR Nature. 2014;510(7505):397-401. doi:10.1038/nature13264.PubMedUsed to support: Landmark mechanistic study in C. elegans demonstrating alpha-ketoglutarate extends lifespan by inhibiting ATP synthase and TOR signaling — foundational mechanistic support for animal lifespan extension across species. Animal/invertebrate study.
  3. Gyanwali B, Lim ZX, Soh J, Lim C, Guan SP, Goh J, Maier AB, Kennedy BK Alpha-Ketoglutarate dietary supplementation to improve health in humans Trends Endocrinol Metab. 2022;33(2):136-146. doi:10.1016/j.tem.2021.11.003.PubMedUsed to support: Comprehensive human-focused review of AKG supplementation covering biological age, bone density, muscle health, and wound healing — summarizes the clinical evidence base for multiple AKG benefits including bone density/strength and protein synthesis.
  4. Sandalova E, Goh J, Lim ZX, Lim ZM, Barardo D, Dorajoo R, Kennedy BK, Maier AB Alpha-ketoglutarate supplementation and BiologicaL agE in middle-aged adults (ABLE)-intervention study protocol Geroscience. 2023;45(5):2897-2907. doi:10.1007/s11357-023-00813-6.PubMedUsed to support: Published protocol for the able Phase 2 RCT of Ca-AKG (1–2 g/day × 6 months) in middle-aged adults targeting biological age reduction; corroborates the 'able Phase 2 RCT ongoing' benefit and the 1–2 g/day studied dose.