Overview

Calcium alpha-ketoglutarate (Ca-AKG) is the calcium salt form of alpha-ketoglutaric acid, a naturally occurring organic acid that serves as a critical intermediate in the tricarboxylic acid (TCA) cycle. Alpha-ketoglutarate participates in numerous metabolic processes, including amino acid synthesis, nitrogen transport, and the regulation of hypoxia-inducible factor (HIF) signaling through its role as a cofactor for prolyl hydroxylase enzymes.

Research interest in Ca-AKG has expanded significantly following a 2020 study published in Cell Metabolism that demonstrated its ability to extend lifespan and compress morbidity in aged mice. The study found that Ca-AKG supplementation reduced frailty, improved fur quality, and delayed age-related decline without observable adverse effects. These longevity effects are thought to involve modulation of DNA methylation patterns and reduction of systemic inflammation, as measured by decreased levels of circulating inflammatory cytokines.

In addition to its longevity applications, Ca-AKG provides supplemental calcium for bone metabolism and may support collagen synthesis and wound healing. Athletes have used alpha-ketoglutarate supplements for potential ergogenic benefits, including improved energy production and reduced ammonia accumulation during exercise. The compound is available as a dietary supplement and continues to be studied in human clinical trials examining its effects on biological aging markers, including epigenetic clocks.

Mechanism of Action

TCA Cycle Intermediate & Anaplerotic Substrate

Calcium alpha-ketoglutarate (Ca-AKG) provides the calcium salt of alpha-ketoglutarate (AKG), a key intermediate in the tricarboxylic acid (TCA) cycle positioned at the critical junction between carbon catabolism and nitrogen metabolism. AKG is produced from isocitrate by isocitrate dehydrogenase (IDH) and converted to succinyl-CoA by the alpha-ketoglutarate dehydrogenase complex (OGDH). As an anaplerotic substrate, exogenous AKG replenishes TCA cycle intermediates depleted during amino acid biosynthesis, gluconeogenesis, and periods of high metabolic demand (PMID: 16702348).

Alpha-Ketoglutarate-Dependent Dioxygenases

AKG serves as the obligate co-substrate for a large family of Fe(II)/2-oxoglutarate-dependent dioxygenases — over 60 enzymes in humans. These include: (1) prolyl hydroxylases (PHD1-3/EGLN1-3) that regulate HIF-1alpha stability and oxygen sensing, (2) TET (ten-eleven translocation) DNA demethylases that oxidize 5-methylcytosine to 5-hydroxymethylcytosine, governing epigenetic reprogramming, (3) JmjC-domain histone demethylases (KDMs) that remove methyl marks from histones, and (4) collagen prolyl-4-hydroxylase essential for collagen triple helix stability (PMID: 25564737).

Longevity & Epigenetic Mechanisms

In C. elegans and mouse models, AKG supplementation extends lifespan by 50% and compresses morbidity. The mechanism involves inhibition of ATP synthase (complex V) and TOR signaling, mimicking caloric restriction. AKG also modulates the epigenetic landscape through TET-mediated DNA demethylation and histone demethylation, resetting age-associated hypermethylation patterns. The biological age reduction measured by DNA methylation clocks in mouse studies was approximately 8 years in human-equivalent terms (PMID: 32877690).

Nitrogen Metabolism & Glutamate Shuttle

AKG is the primary nitrogen acceptor in amino acid catabolism, receiving amino groups via aminotransferases (ALT, AST) to form glutamate, which is then processed by glutamate dehydrogenase or glutamine synthetase. This role in ammonia detoxification makes AKG supplementation beneficial during intense exercise or catabolic states (PMID: 18721930).

Reconstitution Calculator

Research

Safety Profile

Safety Profile: Calcium Alpha-Ketoglutarate

Common Side Effects

• Gastrointestinal discomfort (bloating, gas, mild nausea) in ~5-10% of users
• Diarrhea at higher doses
• Calcium-related constipation
• Mild headache
• Metallic or chalky taste

Serious Adverse Effects

• Hypercalcemia: Excessive intake may elevate serum calcium, causing confusion, fatigue, kidney stones, cardiac arrhythmias
• Kidney stones: Increased calcium excretion may promote calcium oxalate stone formation in susceptible individuals
• Metabolic alkalosis: Theoretical risk with very high doses due to calcium salt load
• Cardiac arrhythmias: In context of hypercalcemia, QT shortening and arrhythmias possible

Contraindications

• Hypercalcemia or conditions predisposing to hypercalcemia (hyperparathyroidism, sarcoidosis, certain malignancies)
• History of calcium-containing kidney stones
• Severe renal impairment (reduced ability to excrete calcium)
• Hypervitaminosis D (potentiates calcium absorption)
• Digitalis/digoxin therapy (hypercalcemia potentiates digoxin toxicity)

Drug Interactions

• Digoxin: Hypercalcemia potentiates cardiac glycoside toxicity; monitor calcium levels closely
• Thiazide diuretics (hydrochlorothiazide): Reduce renal calcium excretion, increasing hypercalcemia risk
• Bisphosphonates (alendronate): Calcium may impair absorption; separate doses by at least 2 hours
• Tetracycline/Fluoroquinolone antibiotics: Calcium chelation reduces antibiotic absorption; separate by 2-4 hours
• Levothyroxine: Calcium impairs absorption; administer 4+ hours apart
• Iron supplements: Mutual absorption interference; separate dosing by 2+ hours
• Calcium channel blockers: Theoretical antagonism; clinical significance uncertain but monitor blood pressure

Population-Specific Considerations

• Pregnancy/Lactation: AKG is an endogenous metabolite; calcium needs increase during pregnancy. However, supplementation with CaAKG specifically lacks gestational safety data; consult physician
• Pediatric: Limited data; calcium supplementation is common in children but AKG-specific pediatric safety not established
• Elderly: May be beneficial for age-related calcium needs and longevity research (Bryan Johnson protocol); monitor renal function and calcium levels
• Renal impairment: Contraindicated in severe CKD; dose reduction and calcium monitoring needed in mild-moderate impairment
• Patients on multiple supplements: Account for total daily calcium intake (diet + supplements) to avoid exceeding 2,500 mg/day upper limit

Pharmacokinetic Profile