Calcium Alpha-Ketoglutarate Encyclopedia — Scientific Background

What Is Calcium Alpha-Ketoglutarate?

Calcium alpha-ketoglutarate (Ca-AKG) is the calcium salt form of alpha-ketoglutarate (AKG), a dicarboxylic acid with the molecular formula C₅H₆O₅ and a molecular weight of 146.10 g/mol for the free acid form. The calcium salt (monohydrate) has the molecular formula C₅H₆CaO₆ and a molecular weight of 202.18 g/mol. Ca-AKG is preferred in supplement applications for its enhanced stability and bioavailability compared to free AKG.

The TCA Cycle Connection

AKG is a central intermediate in the tricarboxylic acid (TCA) cycle, positioned at the intersection of multiple metabolic pathways. In the cycle, isocitrate is oxidized and decarboxylated to form AKG, which is then further oxidized to succinyl-CoA, generating NADH that feeds into the electron transport chain for ATP production. AKG also serves as a nitrogen shuttle, collecting excess nitrogen from amino acid metabolism and facilitating its elimination. It serves as a precursor for the synthesis of several amino acids, including glutamate and glutamine, thereby linking carbohydrate and nitrogen metabolism.

Mechanisms of Action

Epigenetic Regulation — The AKG-TET Axis

AKG serves as an obligate cofactor for a large family of dioxygenases, including Ten-eleven translocation (TET) enzymes that demethylate DNA and JmjC-domain-containing histone demethylases. The AKG-TET axis has been identified as a critical regulatory nexus of cellular senescence. Research demonstrates that augmenting AKG bioavailability or TET expression and activity significantly enhances cellular resilience to stress, effectively preventing and reversing senescent phenotypes. Downregulating TET expression or limiting AKG bioavailability triggers widespread epigenetic reprogramming, amplifies pro-inflammatory signaling, and enhances the senescence-associated secretory phenotype (SASP).

Anti-Aging and Longevity

AKG has been introduced as a potential anti-aging metabolite that can control several functions in organisms, thereby increasing longevity and improving healthspan. In mice, dietary AKG supplementation extended both lifespan and healthspan, associated with reduced systemic inflammation and increased IL-10 levels. AKG exerts its effects through different mechanisms such as inhibiting mTOR and ATP-synthase, modulating DNA and histone demethylation, and reducing ROS formation.

Cellular Energy Metabolism

As a key TCA cycle intermediate, AKG directly supports mitochondrial ATP production. AKG plays a crucial role in cell energy metabolism, amino acid/protein synthesis, and stemness and differentiation.

Metabolic Health Support

Exogenous supplementation of AKG improves obesity, blood glucose levels, and cardiovascular disease risks associated with metabolic syndrome. AKG regulates common pathological mechanisms of metabolic syndrome, including inflammation and oxidative stress.

Immune Regulation

AKG plays physiological functions in immune regulation, oxidative stress, and anti-aging. It modulates immune cell function and contributes to the maintenance of immune homeostasis.

The Bioavailability Challenge

Despite its central role in cellular metabolism, native AKG presents significant formulation challenges. AKG has a plasma half-life of less than 5 minutes due to rapid metabolism in enterocytes and the liver. As a charged dicarboxylate, AKG is not a highly membrane-permeable molecule, limiting its absorption across the intestinal epithelium. Following oral administration, AKG is primarily taken up by the liver and rapidly converted to other metabolites, limiting its systemic availability and distribution to peripheral tissues.

liposomal encapsulation addresses these limitations through a biomimetic phospholipid bilayer that protects AKG during digestive transit, prevents premature metabolism, and facilitates direct delivery to mitochondria. Conventional pills and powders show limited AKG absorption, while the liposomal structure creates a protective layer around nutrients, keeping them away from gastric acid and maintaining optimal bioavailability.

Liposomal Calcium AKG

Liposomal encapsulation of Ca-AKG provides a fundamentally different delivery mechanism from conventional forms. The phospholipid bilayer surrounds the AKG molecule, forming a protective shell that enhances absorption and facilitates direct delivery to target tissues. This delivery system:

• Protects AKG from gastric acid degradation and premature metabolism

• Enhances intestinal absorption through lipid-mediated pathways

• Facilitates direct delivery to mitochondria, the primary site of AKG's metabolic activity

• Provides sustained release for prolonged metabolic support

Liposomal Ca-AKG is supplied as a sunflower phospholipid liposomal powder, typically as white to off-white fine powder. Commercial liposomal Ca-AKG products commonly provide 700 mg Ca-AKG per capsule with sunflower oil (phosphatidylcholine) as the liposomal carrier.

Clinical Evidence

Biological Age Reduction

A clinical study by Demidenko et al. (2021) evaluated Ca-AKG (1 g/day) with vitamins A and D in 42 healthy individuals aged 40–65 years for an average of 7 months. The study demonstrated an average reduction in biological age of approximately 8 years as measured by DNA methylation.

ABLE Trial

The ABLE trial (Alpha-ketoglutarate Supplementation and BiologicaL agE) is a double-blind, placebo-controlled randomized trial assessing the effects of 1 g sustained-release Ca-AKG versus placebo over 6 months, followed by 3 months of follow-up, in 120 generally healthy adults aged 40–60 years with a higher biological age (assessed by DNA methylation clocks) than chronological age. The trial demonstrated the feasibility of recruiting biologically older yet generally healthy middle-aged adults for gerotherapeutic interventions.

Healthy Aging Trial

An ongoing randomized, double-blind, placebo-controlled trial is evaluating Ca-AKG supplementation (2 g/day) over 12 weeks in 30 healthy volunteers aged 40–75 years. The primary outcome is changes in PhenoAge, a measure of biological aging based on biomarkers. Secondary outcomes include bone health and calcium content, physical strength and body composition, metabolic markers including blood glucose and cholesterol, immune function markers, quality of life measures, and physical activity levels.

Hemodialysis Safety

Several clinical trials using Ca-AKG in hemodialysis patients found it to be safe at doses up to 4.5 g/day, with increases in plasma arginine and decreases in plasma urea levels.

Safety and Regulatory

Calcium alpha-ketoglutarate is Generally Recognized As Safe (GRAS) under U.S. FDA guidelines and is included in the U.S. list of old dietary ingredients, allowing lawful use as a food ingredient. Clinical trials have used Ca-AKG at doses up to 4.5 g/day in hemodialysis patients and up to 2 g/day in healthy aging studies without serious adverse effects. The expert panel concluded that Alpha-Ketoglutaric Acid and Alpha-Ketoglutarate Calcium are safe under the Federal Food, Drug, and Cosmetic Act and meet the criteria for GRAS status in accordance with 21 CFR §170.30. Testing protocols must adhere to international standards including USP, European Pharmacopoeia, and FAO/WHO Codex Alimentarius. Formulators should verify local regulatory requirements prior to market entry.

This product is intended for research, nutraceutical, and functional food applications. Not intended to diagnose, treat, cure, or prevent any disease.

89$/KG

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