Alpha-Ketoglutarate (AKG / Calcium AKG)

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

TCA cycle intermediate and key metabolic node — substrate for amino acid synthesis, dioxygenase enzymes (including epigenetic modifiers TET, JmjC), and energy metabolism. Animal studies show lifespan extension. Demidenko 2021 Rejuvant study (n=42, calcium-AKG + vitamins) reported 8-year DNA methylation age reduction over 7 months. ABLE Phase 2 trial ongoing. Promising but small-sample evidence.

Studied Dose REJUVANT/CA-AKG (Demidenko 2021): 1000 mg sustained-release × 4-10 mo. ABLE: 1-2 g/day × 6 mo. POST-SURGICAL: 2-30 g/day. Free AKG poor bioavailability (<5 min t½) — Ca-AKG salt preferred.
Active Compound Alpha-ketoglutarate (α-KG, 2-oxoglutarate) — TCA cycle intermediate. Most stable supplement form: CALCIUM ALPHA-KETOGLUTARATE (Ca-AKG). Other forms: ammonium AKG, sodium AKG (used clinically post-surgery)

Benefits

Biological age reduction (Demidenko 2021 — small study)

Demidenko 2021 (PMC8660611) longitudinal observational study followed 42 self-reported healthy individuals taking Rejuvant (sustained-release Ca-AKG + sex-specific vitamins) for 4-10 months. AVERAGE 8-YEAR REDUCTION in biological age (TruAge DNA methylation test) over 7 months. Substantial effect size if real. CRITICAL CAVEATS: (1) self-reported, no placebo control, (2) single DNA methylation clock used, (3) selection bias possible, (4) small sample (n=42), (5) Ca-AKG combined with vitamins (cannot attribute to AKG alone). Hypothesis-generating, not confirmatory.

ABLE Phase 2 RCT ongoing

ABLE trial (NCT05706389, National University of Singapore Phase 2 RCT) 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 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. Asadi Shahmirzadi 2020 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 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 — mechanism for biological age effects observed in Demidenko 2021.

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
Demidenko 2021 — Rejuvant (Ca-AKG) Biological Age
PubMed

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, PMID 34847777). PMC8660611.

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 Shahmirzadi 2020 — Ca-AKG in Mice (Foundational Animal)
PubMed

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)
PubMed

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 Demidenko 2021 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 the recommended dosage of Alpha-Ketoglutarate (AKG / Calcium AKG)?

The clinically studied dose for Alpha-Ketoglutarate (AKG / Calcium AKG) is REJUVANT/CA-AKG (Demidenko 2021): 1000 mg sustained-release × 4-10 mo. ABLE: 1-2 g/day × 6 mo. POST-SURGICAL: 2-30 g/day. Free AKG poor bioavailability (<5 min t½) — Ca-AKG salt preferred.. Always follow product labeling and consult a healthcare provider for personalized dosing recommendations.

What is Alpha-Ketoglutarate (AKG / Calcium AKG) used for?

Alpha-Ketoglutarate (AKG / Calcium AKG) is studied for biological age reduction (demidenko 2021 — small study), able phase 2 rct ongoing, animal lifespan extension across multiple species. Demidenko 2021 (PMC8660611) longitudinal observational study followed 42 self-reported healthy individuals taking Rejuvant (sustained-release Ca-AKG + sex-specific vitamins) for 4-10 months.

Are there side effects from taking Alpha-Ketoglutarate (AKG / Calcium AKG)?

Reported potential side effects may 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. Always consult a healthcare provider before starting any new supplement, especially if you have underlying conditions or take medications.

Does Alpha-Ketoglutarate (AKG / Calcium AKG) interact with medications?

Known drug interactions may 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. Consult a pharmacist or healthcare provider if you take prescription medications.

Is Alpha-Ketoglutarate (AKG / Calcium AKG) good for longevity?

Yes, Alpha-Ketoglutarate (AKG / Calcium AKG) is researched for Longevity support. AKG extends lifespan in fruit flies, C. elegans roundworms, and mice. Asadi Shahmirzadi 2020 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.